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Plenary Lectures

PL 01

PL 02

SLEEP-WAKE REGULATION BY PROSTAGLANDINS D2 AND E2 O. Hayaishi Although we spend almost one third of our lifetime sleeping in bed or somewhere else, the molecular m e c h a n i s m of sleep-wake regulation has thus far been very little understood. During the last several decades, an intensive search for endogenous sleep-regulating substances has been carried out in a number of laboratories throughout the world. In this presentation, I wish to briefly review current knowledge about the sleep-regulating activity of prostaglandins and to discuss (i) Prostaglandins and their receptors in the brain (2) Sleep-inducing effect of PGD2 (3) Awaking effect of PGE2 (4) Other sleep-regulating substances and their relation to PGD2 and PGE2 (5) Tentative conclusions and hypothesis. Finally I would like to propose the working hypothesis that prostaglandins PGD2 and E2 induce sleep and wakefulness, respectively, and that the balance of these two substances in t.heir respective center is, at least in part, responsible for the sleep-wake cycle. Director, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita Osaka 565, Japan

ESS~I~TIAL DRUGS FOR ALL IN THE YEAR 2000 REALITY OR FICTION ? I. Darmansj ah Drugs are an essential part of health service and therefore they should be available and accessible sufficiently in terms of variety, quantity, as well as quality, where they are needed. Unfortunately this has not always been able to attain in many countries where sources of funds are restricted and priority has been given to othe~ pressing country problems. But apart from the last mentioned, even affluent countries have difficulties in coping with the global trend of increased drug consunption. Since its first conception of the WHO mediated Essential 9 Drugs Policy,which is a c(mponent of a National Drug Policy, in 1977, it became evident that a limited n%~aber of drugs (the real number is not important, hut the principle is) is satisfactory to cope with 90% of real health needs. Inplementing an Essential Drugs Policy however may mean two possibilities; for affluent countries this would mean depriving one from a wider choice of drugs, hut for many developing countries the availability of essential drugs would mean an even larger budget for drug procur~nent. Rich as well as poor countries however, will face their own problems as regards to drug use an ~he ~ a r 2000. In the wealthy countries the increased demand for drugs and escalating drug prices will result in higher drug expenditure which is nowadays illustrated by the Japanese situation with an annual per capita drug censtmlotion of over $ 200. In developing countries drug expenditure is in the range of a few dollars per capita with a very skewed distribution, and here the problem is one of nonaffordance for sizable percentages of populations. While it was anticipated in the 70-s that the proportion of drug cons~nption of developing countries would increase in relation to the industrialized countries, the WHO Report on the "World Drug Situation" (1988) reveals a proportional decline of pharmaceutical consumption in the third world fram 24 % in 1976 to 2 1 % in 1985, while its population have increased from a proportion of 73 to 75 % of the whole world. Although many factors do obscure this -

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PL 04

Cont. PL 02 picture, surveys showed that in more than I00 developing countries a large part of the population do not get access to drugs. It is clear that adequate drug use in developing countries is hampered by poverty, while both in developed countries and the upper segment in developing countries an overuse is likely to continue. A delicate balance ought to be struck between satisfying economic needs for drug * develolxnent and real health needs. With only ii years ahead it seems improbable that the availability of essential drugs in the year 2000 will be reality for all of us, unless the econcmic situation changes for the bettezment of developing countries. Now, there is even more reason to limit the use of inessential drugs and for goverr~aents to reappraise their National Health and Drug Policies and reformulate their political will. These should result in smoothening conflicts of interests which are so numerous in the field of drugs, The participation of clinicians to accept and impl~ment the Essential Drugs Concept and Polic,y is still far frc~ reality; more needs to be done to inform and convert prescribers on the still widespread misconceptions related to Essential Drugs. _Meanwhile, Rational Drug Use as part of the WHO Drug Action Programme must be canloaigned in each (developing) country to form the strong basis for therapy, which is the ultimate goal of the Essential Drugs Concept. But, ...... who should hell the cat ? Department of Pharmacology, University of Indonesia, 6 Salemba, Jakarta 10430, Indonesia.

S. Gershon Decrements of cognitive function occur most commonly and to a major extent in the pathological disorders associated with aging. SDAT (Senile Dementia Alzheimers' Type) and MID ( M u l t i - l n f a r c t Dementia) are the key c l i n i c a l disorders in which cognitive d e f i c i t s present serious c l i n i c a l and public health problems. A broader scope of such dysfunctions also occur in neurological disorders such as stroke, c l i n i c a l head i n j u r y , attention d e f i c i t disorders and drug induced d e f i c i t s . Recently, age associated memory impairment (AAMI) has been described as an issue of c l i n i c a l and academic i n t e r e s t as well as a p o t e n t i a l t a r g e t population f o r evaluation of new cognition enhancing agents. Treatment s t r a t e g i e s have concentrated on SDAT and MID where postulated e t i o l o g i e s have presented ent i ci ng treatment approaches. As a r e s u l t , e a r l y attempts to ameliorate memory d e f i c i t s focused on increasing blood flow or the supply of oxygen to the brain. In recent years, research has been directed mainly at the chol i ner gi c nervous system because a number of s i g n i f i cant changes occur within the c h o l i n e r g i c system in brains of SDAT subjects and because agents that i n t e r f e r e with normal c h o l i n e r g i c function d i s r u p t learning and memory. However, the c h o l i n e r g i c system is not the only neurotransmitter system to be af f ec te d by SDAT. I t is also not the only neurotransmitter system suspected of playing a role in learning and memory. Attempts have been made at correcting c h o l i n e r g i c d e f i c i t s as well as manipulation of the other brain neurotransmitter systems. Other modalities have included psychostimulants, metabolic enhancers, neuropeptides and nootropics. The presentation w i l l c r i t i c a l l y assess the data from such c l i n i c a l t r i a l s and w i l l present information on some new classes of agents c u r r e n t l y under i n v e s t i g a tion. Samuel Gershon, M.D.; U n i v e r s i t y of Pittsburgh; Western Psychiatric I n s t i t u t e & C l i n i c ; 38110'Hara Street; Room E-1019; Pittsburgh, PA 15213

PL 03 COMPUTER MODELING AND PHARMACEUTICAL RESEARCH

THERAPEUTIC APPROACHES TO THE TREATMENT OF COGNITIVE IMPAIRMENT

STRUCTURAL

DATABASES

IN

K. Mueller, H.J. Ammann, D.M. Doran, P.R. Gerber, K. Gubernator, G. Schrepfer FaCilities for quick manipulation, examination, and comparison of complex three-dimensional molecular structures are essential prerequisites in modern structure-oriented chemical research. They are provided by our Computer Modeling systems RIMG (Roche Interactive Molecular Graphics) and MOLOC (MOdeling on LOw-Cost terminals), which have been developed at Hoffmann-LaRoche, Basel. These modeling systems are highly functional expert systems. They are built around powerful generally applicable united-atom force field methods. They are equipped with novel algorithms for structural superposition, macrocyclic conformation analysis, and structural screen facilities. They are linked to the two database systems ROCSD (Roche Cambridge Structural Database) for X-ray structures of small molecules (original data from the Cambridge Structural Datafiles) and ROPDB (Roche Protein Structural Database) for protein X-ray structures (original data from the Brookhaven Protein Datafiles). Both databases have been specially designed to allow us quick search and retrieval of substructural information. It is the effective combination of powerful modeling, structural screening, and data compacting tools with a quick access to a wealth of three-dimensional structure information, which makes our expert systems to very potent research instruments. Their use is illustrated by examples taken from recent research projects. F. Hoffmann-La Roche & Co. AG, Central Research Units, CH-4002 Basel, Switzerland.

AS

PL 05 ATHEROSCLEROSIS G V R Born

- WHAT

CHANCES

FOR

DRUGS?

The cautious answer is - better all the time, as increased understanding of the pathogenesis is opening new intervention possibilities. The importance of this understanding can be gauged by the enormous effort and expense invested in anti-platelet and thrombolytic drugs: although vital, these drugs chase horses after the stable door is closed. The need for concentrating on drugs against the dangerous, ultimate consequences of atherosclerosis is, of course, imposed by its tendency to progress without clinical manifestations. This has also restricted possibilities for determining therapeutic effectiveness in the earlier stages of the disease. Angiographic techniques under development are beginning to overcome these limitations, with respect to reversibility as well as to prevention. The strong and causal relation established between the risk of coronary heart disease and elevated serum cholesterol levels constitutes the basis for treatment of hyperlipidaemias, by diet alone or with lipid-lowering drugs. Their different modes of action now include promising HMG-CoA reductase inhibitors. Other conceivable drug interventions through diminishing lesion development are by inhibiting uptake and modification of low density lipoprotein; by antagonising cellular proliferation; by reducing calcium deposition; and by preventing plaque fissure. Some of these possibilities are under investigation.

sodium nitroprusside and phenylephrine were infused to vary the degree of baroreceptor activity. The alpha?-adrenoceptor antagonists yohimbine and rauwoYscine shifted the plasma noradrenaline versus sympathetic nerve activity function curve in such a way that, for a given rate of sympathetic firing, the noradrenaline concentration was higher than in the absence of the antagonists, indicating the physiological operation of presynaptic alpha2-adrenergic autoinhibition at postganglionic sympathetic neurones. Activation by the endogenous agonist makes presynaptic autoreceptors interesting from the physiological point of view, but at the same time hinders their exact pharmacological characterization because the endogenous transmitter often is present in the receptor biophase at unknown concentrations. Single pulse stimulation of brain slices is a recently developed possibility to evoke an easily measurable radiolabelled transmitter release free from autoinhibition and, hence, to determine "true" agenist potencies and antagonist affinities at presynaptic autoreceptors. One result is that, in contrast to what was believed, phentolamine blocks presynaptic serotonin autoreceptors in rat and rabbit brain. The increase, by phentolamine, of the release of serotonin is not due to removal of a presumed alpha?-noradrenergic heteroinhibition but to b~ockade of the 5-HT I receptor-mediated presynaptic autoinhibition. Institut fHr Pharmakologie und Hermann-Herder-Strasse 5, D-7800 Br., Germany

Toxikologie, Freiburg i.

Department of Pharmacology, King's Colleqe, Strand, London WC2R 2LS England.

PL 06

PL 07

PHYSIOLOGY AND PHARMACOLOGY OF PRESYNAPTIC AUTORECEPTORS K. Starke, N. Limberger and B. Szabo

GENE TECHNOLOGY AS A SOURCE OF NEW DRUGS H. G. Gassen Rarely a method in biology has influenced neighbouring disciplines such as medicine and biotechnology comparable to gene technology. In 1972 Cohen and Boyer discovered that foreign DNA when brought into a bacterial cell in form of a plasmid is duely propagated..The new genetic information is needless of its origin - transcribed into RNA which may be translated in a protein. By this basic experiment biology turned into an information handling science. The discovery of the mosaic structure of eukaryotic genes, the mechanism of antibody diversity or mobile genetic elements was due to the application of DNA recombination technics. Gene technology proved to be a valuable method for the production of new drugs, especially h u m a n therapeutic proteins. Initially well known drugs such as insulin or growth hormones could be produced in unlimited quantities and higher purities by recombinant microorganisms. Next, new compounds turned up such as interleukines and growth factors which could only be isolated and identified by recombinant DNA techniques. In the years to come the battery of techniques available will be used to optimize the synthesis of low molecular weight nonprotein therapeutics. In the long run, however, pharmacology will turn back to chemistry, but on a better biological background. The practical aspects of tho lecture will concentrate on the interaction of proteinases and their inhibitors and on the

Many neurones express autoreceptors, i.e., receptors for their own transmitter. The effect mediated by autoreceptors located in the somadendritic region often is inhibition of action potential generation, whereas the effect mediated by autoreceptors at the terminals presynaptic autoreceptors - often is inhibition of action potential-evoked transmitter release. Neurones express many receptors which normally remain silent because the respective endogenous agonist never reaches them at sufficient concentrations; such receptors can be activated only pharmacologically by administration of exogenous agonists. For several presynaptic autoreceptors, however, activation by the endogenous agonist has been demonstrated, as shown by the following three examples. First, in slices of rabbit brain, the release of noradrenaline, dopamine, serotonin and acetylcholine elicited by the first pulse of a train of 4 or 8 pulses is much higher than the release elicited by the folldwing pulses. Appropriate autoreceptor antagonists greatly attenuate this decrease in per pulse release, indicating that the decrease is due to endogenous, autoreceptor-mediated inhibition. Second, local application of the appropriate autoreceptor antagonists into dialysis tubes implanted into the brain increases the local release of noradrenaline and depamine in freely moving rats, indicating presynaptic autoinhibition in the central nervous system in vivo (Dennis et al., J. Pharmacol. exp. Ther. 241, 642, 1987; Imperato and Di Chiara, Eur. J. Pharmacol. 156, 385, 1988). Third, we recently studied blood pressure, postganglionic renal sympathetic nerve activity and the plasma noradrenaline level in anaesthetized rabbits;

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Cont. PL 07 morphology of the blood-brain barrier. Proteinase inhibitors are excellent model components to study the specificity of protein-protein interaction. Furthermore, they represent valuable drugs for the treatment of inflammation. Chemical gene synthesis as well as site-directed mutagenesis are the major tools to optimize the inhibitory action of these proteins in the sense of protein design. Subtractive cloning may be used to characterize the proteins of the brain capillary endothelium which represent the basic principle of the blood-brain barrier. The genes for proteins such as the ~' -glutamyltranspeptidase, the glucose transporter or the apolipoprotei n A1 serve as genetic markers to investigate the influence of the cell environment - for example interactions with astrocytes - on the function and morphology of the brain-specific endothelium cells. A better understanding of the structure of this barrier may help to clarify the transport problems involved in metabolite exchange between the blood and the brain. Institut ffir Biochemie der Technischen Hochschule Darmstadt, Petersenstr. 22, D-6100 Darmstadt

PL 08 ENDOGENOUS' OPIATE ALKALOIDS S. Spector Endogenous codeine and morphine were identified in rat brain by immunological determination following HPLC. To demonstrate occurrence of a biosynthetic pathway to morphine in mammals similar to that used by the poppy plant (+) salutaridine, ( - ) , thebaine and (-) codeine were administered to rats intravenously. These compounds which are intermediates in the synthesis of morphine in Papaver Somniferum, caused a marked increase in the codeine and morphine levels in rat tissues. The concentrations of these two opiate alkaloids seems to be distributed uniformly in the cortex, midbrain, pons/medulla and cerebellum. The spinal cord and the adrenal gland have high levels of morphine and codeine and the adrenal has more codeine than morphine. The levels of morphine in the spinal cord and the urinary excretion of morphine are elevated in the a r t h r i t i c rat model. Extracted alkaloid samples from the a r t h r i t i c rats spinal cord were analyzed by GC-mass spectrometry and found molecular ions identical with morphine and codeine. The possible physiological roles of endogenous morphine and codeine w i l l be discussed. Roche Institute of Molecular Biology, Department of Neurosciences: Nutley, New Jersey 07110, U.S.A.

PL 09 THE DILEMMA OF DRUGDEVELOPMENTFOR TROPICAL DEVELOPING COUNTRIES S. Bergstr~m Improving the health status in developing countries is often a complex and d i f f i c u l t problem related to education and development. The proper use and distribution of the most common "essential" drugs is in many areas s t i l l not possible. Another problem has been the r e l a t i v e l y small research and development e f f o r t s - both in academies and industry - on some of the widespread diseases and problems of tropical countries lacking effective therapeutic or preventive methods. Other problem has to be solved with innovative approaches when research products are to be brought to effective use in the health services in developing countries. Some of these problems will be reviewed. Karolinska I n s t i t u t e t , Box 60250, S-IO4 Ol Stockholm

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Symposia

S 01.01 G E N E T I C POLYMORPHISMS OF DRUG M E T A B O L I Z I N G ENZYMES: MOLECULAR MECHANISMS Urs A. Meyer, D. M. Grant and M. Blum For m a n y of the known d r u g m e t a b o l i z i n g enzymes genetic p o l y m o r p h i s m s have been d e m o n s t r a t e d or are suspected. These p o l y m o r p h i s m s give rise to distinct subgroups in the population which differ in their ability to p e r f o r m a c e r t a i n drug b i o t r a n s f o r m a t i o n reaction. The molecular M e c h a n i s m s of three common p o l y m o r p h i s m s have been studied in this laboratory. The d e b r i s o q u i n e / s p a r t e i n e - t v p e p o l v m o r p h i s m of drug oxidation affects the m e t a b o l i s m by cytochrome P450IIDI of over 25 clinically used drugs including ~ - a d r e n e r g i c blocking agents, antiarrhythmics, antidepressants, opioids and others. A P450IIDI cDNA has been prepared and the locus of the IIDI gene (CYP2D) on chromosome 22 has been characterized. Several m u t a tions have been identified in the DNA derived from p r e m R N A of livers of poor m e t a b o l i z e r s (PM) of debrisoquine, all leading to deficient synthesis or unstable P450IIDI (i, 2). In leucocyte DNA of families of subjects phenotyped in vivo as poor m e t a b o l i z e r s of d e b r i s o quine, two different restriction fragment length polymorphisms (RFLPs) associated with the PM phenotype were detected with the P450IIDI cDNA. At least one mutated allele of the IIDI gene can be d e m o n s t r a t e d in DNA of 75 % of poor m e t a b o l i z e r s of d e b r i s o q u i n e (2). The m e D h e n y t o i n - t y p e p o l v m o r D h i s m affects the m e t a b o l i s m of mephenytoin, nirvanol, m e p h o b a r bital, hexobarbital, propranolol and d i a z e p a m and is caused by a deficiency of a P450 (P450meph, P450MP) of the IIC family. However, w h i c h

one of the m u l t i p l e genes of this family is affected has not yet been determined (3,4). The p o l y m o r p h i s m of N - a c e t v l t r a n s f e r a s e (NAT) affects the m e t a b o l i s m of a wide v a r i e t y of arylamine and hydrazine drugs. It was first studied by purifying and c h a r a c t e r i z i n g NAT. Two forms of NAT could be separated by ionexchange c h r o m a t o g r a p h y of human liver cytosols. In livers of slow acetylators a 31 kDa protein recognized by anti-NAT antibodies was d r a s t i c a l l y reduced or absent (5). We have isolated from genomic libraries of a p o s i t i v e l y identified heterozygous rapid acetylator a gene (hnatb) w h i c h on expression produces a p r o t e i n with the same activity and Mr as p o l y m o r p h i c NAT. Probes derived from this gene are presently used to characterize the mutation(s) causing absent NAT in slow acetylators. 1 Gonzalez, F.J., Skoda, R.C., Kimura, S., Umeno, M., Zanger, U.M., Nebert, D.W., Gelboin, H.V., Hardwick, J.P. & Meyer, U.A. Nature 331, 442-446 (1988). 2 Skoda, R.C., Gonzalez, F.J., Demierre, A. and Meyer, U.A. Proc. Natl.Acad. Sci.UEA 85, 5240-5243, 1988. 3 Meier, U.T. and Meyer, U.A; B i o c h e m i s t r y 26, 8466-8474, 1987. 4 Ged, C., Umbenauer, D.R., Bellwe, T.M., B o r k R.W., Shrivastava, P.K., Shinriki, N., Lloyd, R.S. and Guengerich, F.P. B i o c h e m i s t r y 27, 6929-6940, 1988. 5 Grant, D.M., Lottspeich, F., and Meyer, U.A. FEBS Letters 244, 203-207, 1989 Department of Pharmacology, Biocenter, Univ e r s i t y of Basel, CH-4056 Basel, Switzerland

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S 01.02

S 01.03

POLYMORPHIC DRUGOXIDATION: THERAPEUTICIMPLICATIONS Raymond L~ wPg__sle_~Y_,Heyo K. Kroemer and Lyle Siddoway Because of the usually r e l i a b l e rela{ionship between 'plasma concentration and drug action, one often assumes that patients with the d e f i c i e n t metabolism phenotype (PM) w i l l have greater drug effect than those with the extensive metabolism (EM) phenotype who eliminate the drug more r a p i d l y . Recent experience with three new and potent antiarrhythmic agents (~-encainide, ~-flecainide and~-propafenone) indicates that one cannot generalize about the consequences of polymorphic oxidation and that complete evaluation of the c l i n i c a l pharmacology of an agent is necessary for such predictions. These agents exemplify three d i f f e r e n t variations in which parent drug and metabolites can contribute to drug effects: i ) an active parent compound with inactive metabolites (flecainide), 2) metabolites with a c t i v i t y greater than parent (encainide), 3) parent and metabolites with similar antiarrhythmic potency (propafenone). I t follows that the consequences of polymorphic metabolism w i l l be d i f f e r e n t for each of these agents. Plasma level monitoring of encainide and propafenone concentrations w i l l be of limited value because of the variable presence of active metabolites. There should be a reasonably good r e l a t i o n ship between pharmacologic effects and plasma concentration of flecainide and monitoring should be of value, especially in patients with renal insufficiency. Also, the consequences of drug interactions due to i n h i b i t i o n of metabolism by agents such as quinidine should be d i f ferent for each agent and only manifest in the Er~ phenotype. Beta receptor antagonism is another p o t e n t i a l l y antiarrhythmic action of the (+)-S-isomer of propafenone. Stereo-selective clearance and polymorphic metabolism are factors which possibly contribute to the higher level of beta blockade observed in the PM phenotype after administ r a t i o n of propafenone. Consideration of the role of active metabolites, chiral factors influencing drug action and elimination, drug interactions and alterations in renal clearance may lead to better understanding of the dose-effect relationships for these and possibly many other drugs which are eliminated by polymorphically d i s t r i b u t e d metabolism. Department of Pharmacology, Georgetown University Medical Center, Washington, DC 20007, U.S.A.

Idiopathic diseases metabolising enzymes

and the polymorphic

drug -

R o b e r t L. S m i t h , D e p a r t m e n t of P h a r m a c o l o g y & Toxicology, St. Mary's Hospital Medical School, London, W2 1PG, UK. Despite the major advances t h a t have been made over the past forty years in the diagnosis and t r e a t m e n t of many of the so called idiopathic or 'spontaneous' diseases there has occurred little if any commensurate advance in our understanding of the origins of these conditions. However, the development of four concepts over the past two decades or so, w h e n considered together, perhaps reduce the seemingly intractable n a t u r e of the problem. These conceptual developments are as follows: (1) The recognition t h a t m a n y h u m a n idiopathic diseases are characterised by a high heritability component i.e. discrete genetic factors m a y be major predisposing factors. (2) The recognition in r e c e n t years of the highly polymorphic n a t u r e of the genes regulating the enzymes of xenobiotic biotransformation and in particular those concerned with the oxidative metabolic pathways. These enzymes are known to be of crucial importance in the m a i n t e n a n c e of safe homeostasis with the myriads of organic xenobiotic s u b s t a n c e s e n c o u n t e r e d i n t h e chemical e n v i r o n m e n t . Allelic modifications of t h e s e genes can be predisposing factors for morbidity a n d mortality in individuals carrying t h e m and when exposed to drugs and environmental chemicals. (3) The t h i r d factor is the now well-known observation t h a t various types of spontaneous disease cohorts display m a r k e d e n r i c h m e n t w i t h respect to the frequency of occurrence of a particular drug-metabolising phenotype. (4) Changes in the n a t u r e and incidence of idiopathic diseases a m o n g m i g r a n t peoples who move from one environment to another. These considerations arouse in a forceful m a n n e r the hypothesis t h a t m a n y idiopathic diseases arise from the interplay of genetic and environmental factors. While there has been considerable success in identifying some of the discrete genetic predisposing factors in recent years e.g. in schizophrenia, rheumatoid a r t h r i t i s there h a s been little progress with respect to identifying the possible role of e n v i r o n m e n t a l factors particularly, specific chemical agents. Posed simply, do some idiopathic diseases arise from a genetically determined inability to m e t a b o l i s e a n d h a n d l e e n v i r o n m e n t a l chemicals on a chronic basis? Identification of a n aetiological chemical agent might lead to its elimination from the e n v i r o n m e n t or alternatively to reducing or p r e v e n t i n g t h e exposure of genetically susceptible individuals to the toxic agent. Some examples of how genetic deficiencies of the drugmetabolising enzymes a n d the consequent failure to metabolise specific environmental chemicals can result in "spontaneous" disease will be discussed. These emphasize the importance of the concept t h a t m a n y such conditions reflect the outcome of the interplay of genes a n d e n v i r o n m e n t a l chemicals a n d t h a t t h i s r e a l i s a t i o n s h o u l d g a l v a n i s e a s e a r c h for s u c h substances in our environment.

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S 02.01 PREDICTIVE V A L U E OF A N I M A L E X P E R I M E N T S FOR HUMAN TERATOGENICITY. F r a n k M. S u l l i v a n All d r u g R e g u l a t o r y Authorities have requirements for r e p r o d u c t i v e toxicity testing. T h e r e is e v i d e n c e that the predictive v a l u e of a n i m a l t e s t s for e f f e c t s an f e r t i l i t y is g o o d but t h e r e is s t i l l d o u b t a b o u t t h e i r v a l u e for teratogenicity. Furthermore interest in teratogenicity is w i d e n i n g from just structural malformations s u c h as w a s s e e n w i t h t h a l i d o m i d e to i n c l u d e effects on p o s t n a t a l mental and physical development and behaviour, a n d t h i s is introducing new problems. The m e t h o d o l o g y for animal testing for t e r a t o g e n s is w e l l e s t a b l i s h e d and m o s t g u i d e l i n e s are broadly similar in p r i n c i p l e . The m a i n problem is in t h e e x t r a p o l a t i o n of the r e s u l t s between species a n d to m a n . S o m e of the important factors w h i c h h a v e to be t a k e n i n t o account in e x t r a p o l a t i n g f r o m a n i m a l s t u d i e s to m a n a r e n o w k n o w n a n d t h e s e will. be d i s c u s s e d . C h o i c e of s p e c i e s : Comparison of r e s u l t s in different species using suspect human teratogens and non-teratogens have shown that there is no o n e s p e c i e s w h i c h is c l e a r l y superior to t h e o t h e r s for a n i m a l t e s t i n g . In a r e v i e w by t h e U S A F D A for e x a m p l e it h a s b e e n s h o w n t h a t the m o u s e a n d rat s h o w the h i g h e s t incidence of positive results with known teratogens (~80%) but a l s o h a v e t h e h i g h e s t incidence of f a l s e positives with nan-teratogens. Primates on the other hand only detected a b o u t o n e t h i r d of human teratogens but p r o d u c e d very few false positives. The rabbit provided a good compromise. Mechanisms of a c t i o n : Teratology studies can provide information on t h e m e c h a n i s m s by w h i c h malformations m a y be i n d u c e d in a n i m a l s . A l t h o u g h a d i r e c t e f f e c t on t h e f e t u s is p r o b a b l y the most common, malformations may also result from actions on t h e o t h e r p a r t s of the f e t o - p l a c e n t a l unit, utero-placental b l o o d f l a w or on t h e maternal endocrine system. Knowledge of the differences between animal and human reproductive[ endocrinology a n d the p h a r m a c o d y n a m i c actions of t h e d r u g m a y i n d i c a t e whether a h a z a r d f o r h u m a n s w o u l d be e x p e c t e d or n o t . Dose effect response: Most teratologists believe that a threshold exists for teratogens b e l o w w h i c h no e f f e c t w i l l be s e e n . Thus teratogenic effects observed in a n i m a l s at h i g h d o s e s do n o t i n d i c a t e t h a t e f f e c t s w i l l a l s o be observed at l o w d o s e s . Numerous workers have t r i e d to d e v i s e f o r m u l a e for l o w d o s e r i s k assessment. M o s t of t h e s e r e l a t e t h e t e r a t o g e n i c or o t h e r r e p r o d u c t i v e t o x i c d o s e to t h e dose producing o t h e r s i g n s of t o x i c i t y is the dams. The g e n e r a l f e e l i g is t h a t the m o s t hazardous chemicals are those which produce reproductive toxic effects at d o s e s m u c h l o w e r than those producing other toxic effects. R o l e of k i n e t i c s : An i m p o r t a n t new concept in teratology is t h a t s o m e t e r a t o g e n s may act only when certain threshold l e v e l s in the m a t e r n a l b l o o d or f e t u s a r e r e a c h e d and o t h e r t e r a t o g e n s m a y be m o r e d e p e n d e n t in t h e " a r e a u n d e r the curve". Teratogenic as o p p o s e d to e m b r y o l e t h a l e f f e c t s m a y a l s o be d e p e n d e n t on t h e s e p a r a meters. W o r k on v a l p r o a t e a n d on c a f f e i n e h a v e s h o ~ n t h a t t h e s e d e p e n d on c r i t i c a l plasma l e v e l s for t h e i r t e r a t o g e n i e effects whereas cyclaphophamide m a y be a t e r a t o g e n of t h e other type. Confirmation and extension of s u c h studies w i l l be a c r i t i c a l t o o l in e x t r a polation to m a n . Department of P h a r m a c o l o g y & Toxicology, UMDS (Guy's Campus), University of L o n d o n , London, S E I 9RT.

S 02.02 A CASE-CONTROL SURVEILLANCE SYSTEM POR THE RISK ASSESSMENT OF CONGENITAL ANOMALIES A. C z e i z e l The data-set of the populatlon-based Hungarian Case-Control Surveillance of Congenital Abnormalities is described. The occurrence and distribution of drug in the so-called negative control pregnant women delivering unmalformed babies show a surprlsi~ly high intake during pregnancy. There is no big difference between the total study and negative control materials. The occurrences of true human teratogenic drugs /e.g., hydantoin/ are relatively low. Data imdicate no teratogenic effect in some suspected teratogenic drugs /e.g., all~lestrenol/. The attributable risk of drug intake during pregnancy is low, however, their teratoge~io effect is exaggerated in the clinical practice. Department of Human Genetics and Teratology . WHO Collaborating Centre for the Community Control of Hereditary Diseases, National l~stitute of H~giene, H-1966 Budapest, Gygli ut 2-6.

S 02.03 CLINICAL PHARMACOLOGY IN PREGNANCY: WHAT THE DOCTOR SHOULD DO P. C. Rubln The practising physician faces several problems in dealing with the use of drugs in pregnancy. Some drugs are known to be teratogenlc (eg phenytoin, lithium and warfarin). However, even these drugs cause fetal abnormalities in only a minority of exposures indicating that the mechanism underlying teratogenealty is complex and not simply related to the drug. There may be manyother drugs which cause fetal abnormalities in only a small percentage of exposures. Unfortunately, low grade teratogenecity in the human is very difficult to identify. In addition, considerable species variation means that teratogeneclty is also difficult to predict. The time of greatest teratogenic potential is also the time when many women do not realise they are pregnant. Organogenesis in the human is largely complete by about 56 days following conception. It is during this period that drugs can cause structural abnormalities. Even if there were a comprehensive llst of drugs which are teratogenlc in the human it would still be difficult to avoid unplanned exposure. When a woman is receiving longterm drug therapy, prepregnancy counselling is very important in order to minimlse the risks of drug induced abnormality while maximising the quality of disease control. Later in the pregnancy some drugs can cause problems (eg indomethacin and premature closure of ductus arteriosls; and the use of regular aspirin doses near the end of pregnancy causing hoemostatic problems in the neonate). I t should be remembered that pregnancy can e f f e c t drugs, as well as vice versa. Several factors can lead to decreased plasma drug concentrations. Pregnancy is associated with considerable fluid retention as well as a decrease in albumin concentration. In addition, renal plasma flow increases by about 100% towards the end of pregnancy and some metabolic pathways are probably induced. Commonly used drugs for which therapeutic drug monitoring is normally employed (eg phenytoln, aarbamazepine or theophylllne) should be monitored during pregnancy with drug doses adjusted accordingly.

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S 03.01 NONINVASIVE METHODS TO MEASURE CARDIOVASCULAR DRUG ACTIONS G.G. B e l z , K. B r e i t h a u p t , K. E r b r V. S c h r o e t e r Methods in c a r d i o v a s c u l a r clinical pharmacology Should allow: (i) t o d e t e c t d r u g e f f e c t s q u a l i tatively and to establish their haemodynamic profile, (ii) t o q u a n t i t a t e drug effects and to establish their dose-(concentration-)effect relationship, a n d (iii) t o e v a l u a t e t h e t i m e c o u r se of t h e d r u g e f f e c t s . D r u g s c a n a f f e c t v a r i o u s parameters of t h e c a r d i o v a s c u l a r system: blood pressure, cardiac output, total peripheral resis t a n c e ( w h i c h is to b e c a l c u l a t e d ) , stroke volume, heart rate, contractility, pre- and afterload, and others. We have found a spectrum of methods u s e f u l in a s s e s s i n g t h e s e haemodynamic determinants noninvasively and repetitively: the detection of f a s t a r t e r i a l w a l l m o v e m e n t s (Inf r a t o n T e n s i o m a t R) o r t h e s e r v o p l e t h y s m o m a n o m e -~ ter ( F i n a p r e s R) g i v e r e a d i n g s w e l l representative of intraarterial blood pressure. Doppler blood flow and aortic diameter can be recorded simultaneously providing a useful estimate of cardiac output (QuantascopeR). The electrical impedance cardiography ( K a r d i o - D y n a g r a p h ~) is a useful and easy to handle alternative, preferably for d e t e c t i o n o f c h a n g e s of c a r d i a c output within a -24h period. Systolic time intervals from ecg, phonocg and carotid pulse curve detect global left ventricular performance (PEP and PEP/LVET); QS=c provides valid information about contractility. M-mode echocardiography allows to estimate drug effects on preload and afterload. The available tools allow characterization of the pharmacodynamic p r o f i l e of o l d a n d n e w d r u g s in h u m a n s .

and maintaining levels of performance suitable for subsequent testing. Further, such assessments could indicate the effects of drugs on specific systems. These approaches may become more valuable in the future as information is gathered on the basic physiology of the measurements to allow appropriate interpretation of the data. Electroencephalography (EEG) has been used widely in the study of drug action in man, and much effort continues to he devoted to the understanding of the data. Prediction of therapeutic effect from the EEG remains problematical, s it is a sensitive indicator of the presence of central activity and, in this way, is complementary to behavioural measures. Indeed, the EEG can indicate the persistence of drug action in man, and can be interpreted in terms of changes in the level of arousal. Modulation of the electrical activity of the brain may one day be related to altered behaviour, but this may prove to be difficult in the absence of any corroborative evidence. However, studies on event-related potentials may provide information on more system-specific effects, particularly as far as memory and attention are concerned. The Sleep Electroencephalogram records the cyclicity of REM sleep and the continuity of non-REM sleep. Increasing knowledge of the pharmacological control of sleep will, therefore, provide insight into the central effects of drugs. Advances in understanding the control of REM sleep and the subtleties of the pharmacological modulation of nocturnal wakefulness could be used to determine the activity, and possibly indicate mode of action, of drugs acting on the central nervous system.

ZeKaPha, Zentrum fHr Kardiovaskul~re Pharmakologie GmbH, Alwinenstr. 16, 6 2 0 0 W i e s b a d e n , F.R.G.

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S 03.03

MEASUREMENT OF THE CENTRAL EFFECTS OF DRUGS IN MAN

J.R. Malagelada Abstract not received by April 30, 1989

A. N. Nicholson, Peta A. Pascoe and Nicola A. Wright Royal Air Force Institute of Aviation Medicine, Farnberough, Hampshire, United Kingdom The central effects of drugs are measured in many ways, and in this paper we consider various approaches under five headings, i.e. subjective assessments, measurement of performance, tests which detect changes in a neurological function, recordings of the electrical activity of the brain, and sleep electroencephalography. Subjective assessments are used widely in the study of d r u g action in man and they can provide useful information on changes in the level of arousal, alterations in mood and changes in performance. In some circumstances this approach may be a sensitive indicator, though in general it is wise to support such information with objective studies as the ability of an individual to assess change may itself be modified either by immediate effects or by residual sequelae. Measurement of performance has become an indispensable part of the assessment of drugs with central action. This relates to the potentially adverse effects of drugs such as hypnotics, antihistamines and antihypertensives used by the healthy and near-healthy. Many such individuals are involved in skilled work, and this is relevant to the world of transport and industry. However, though many techniques are available, it is increasingly appreciated that skills such as memory, decision making and the quality of interpersonal relationships are difficult to measure. Nevertheless, they are likely to be of significance, perhaps more so than tests of psychomotor activity. In this context, a reappraisal of our approach to the assessment of performance may be timely. Nicholson et al (continued) Tests which measure neurological functions such as tremor, eye-tracking, body sway and tendency to fall asleep during the day can be useful in those, such as the elderly, who may have difficulty in reaching

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S 04.01 B I O M E D I C A L BASIS OF S T E R E O S E L E C T I V I T Y A.H. B e c k e t t It is t w e n t y years ago since I w r o t e the article "Stereochemical Factors in Biological Activity". Until r e l a t i v e l y recently, the i m p o r t a n c e of three d i m e n s i o n s in p h a r m a c o logical actions and drug t h e r a p y has been u n d e r - e m p h a s i s e d and under-utilized. In drug m e t a b o l i s m c o n s i d e r a t i o n of t h r e e d i m e n s i o n s have p l a y e d some role but, in m y opinion, still an insufficient role. In the last few years, it seems to have been r e a l i s e d by regulatory bodies that w h e n a drug c o n t a i n s one or more chiral centres, then we are d e a l i n g with a m i x t u r e of c o m p o n e n t s w h i c h may have different biological p r o p e r t i e s and be d i s t r i b u t e d in the body and e l i m i n a t e d from the b o d y at d i f f e r e n t rates. N a t u r e operates on a t h r e e dimensional p l a n and we have ignored this aspect to our cost. The d e v e l o p m e n t of e n a n t i o s p e c i f i c bioanalysis, e s p e c i a l l y in the past decade, has facilitated probing into the kinetic aspects of the p h a r m a c o k i n e t i c s of drugs and m e t a b o l i t e s in a n i m a l s and man. The r e g u l a t o r y bodies are n o w giving active c o n s i d e r a t i o n to drugs w i t h chiral centres. However, c a u t i o n must be e x e r c i s e d to prevent u n n e c e s s a r y w o r k for the a p p r o v a l of one o s the c o m p o n e n t s of a drug w i t h a chiral centre or c e n t r e s w h e n a m i x t u r e has been g i v e n to m a n for decades. To i l l u s t r a t e the above, e x a m p l e s w i t h chiral centres w i l l be used.

of

drugs

King's C o l l e g e London, C h e l s e a Campus, M a n r e s a Road, L o n d o n SW3 6LX, England.

There are numerous examples of stereoselective hepatic biotransformafion of drugs. Whether or not stereoselective biotransformation produces alterations in the clearance of a drug may depend upon the magnitude of hepatic extraction. For a drug that is highly extracted, clearance may be rate-limited by liver blood flow. In this case, one would not expect stereoselective differences in clearance. An interesting example of a highly extracted compound is propranolol. When administered as the racemate, both enantiomers exhibit similar clearances. However, when administered separately, the S(-)enantiomer has a lower clearance. Apparently, the hemodynamic effect of the S(-)- enantiomer on hepatic blood flow reduces its clearance. For a low extraction ratio compound, differences between the enantiomers in either the plasma protein binding or the intrinsic biotransformation clearance may result in stereoselective clearance. There has been considerable interest in the stereoselective elimination of the nonsteroidal anti-infiammatory drug, ibuprofen. R(-)-ibuprofen, the inactive enantiomer, undergoes enzymatic racemization. The pharmacologic ramification of this inversion is that potency studies in vivo suggest that R(-)-ibuprofen is almost as potent as the S(+)-enantiomer whereas potency studies in vitro indicate that the S(+)-enantiomer is 100 to 200 times more potent. Stereoselective metabolism may be genetically influenced. For example, S(+)-4-hydroxydebrisoquin is produced preferentially in extensive, but not poor, metabolizers of debrisoquin. Recent studies have suggested that stereoselective renal excretion of drugs may occur. The enantiomers of the beta adrenoceptor blocking agent, pindolol, and the diastereomers, quinine and quinidine, are stereoselectively excreted. Stereoselective renal excretion may be due to stereoselectivity in either the metabolism or transport in the kidney. Stereoselective disposition has important ramifications in drug-drug interactions. First, an enantiomer may alter the disposition of the other enantiomer. Secondly, other drugs may interact with racemic compounds. Studies with warfarin have provided considerable insight into the complexities of such interactions. In conclusion, there are examples of stereoselectivity in drug absorption, distribution, metabolism and excretion. Such stereoselectivity has ramifications for rational drug therapy with racemic mixtures. To gain an appreciation of their pharmacokinetics and dynamics, racemic drug products should be treated as combination drugs, not as single entities. School of Pharmacy, University of California, San Francisco, CA,USA

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STEREOSELECTIVE DRUG DISPOSITION K.M. Giacomini Significant progress has been made in understanding the importance of stereoselectivity ha the pharmacokinetics and pharmacodynamics of racemic compounds. In this presentation specific examples of stereoselective drug absorption, distribution, metabolism and excretion will be discussed along with the relevant mechanisms responsible for the stereoselective processes. Where possible, the ramifications of stereoselectivity in drug therapy will be presented. Absorption, defined as the process by which the unchanged drug proceeds from the site of administration to the general circulation, may show stereoselectivity particularly when one considers drugs which are subject to first-pass metabolism or to facilitated transport. Notable examples are verapamil and propranolol, compounds which are highly extracted in the liver and consequently undergo pronounced first-pass metabolism. Important therapeutic consequences of this stereoselective pre-systemic metabolism on the pharmacodynamics of vempamil have been observed. Concentration-response curves are substantially different after oral and intravenous administration when response is related to plasma concentrations of racemic, but not (-)- verapamih Examples of drugs that are stereoselectively transported across the gastrointestinal membranes by facilitated systems are L-dopa and methotrexate. Distribution, which is a function of tissue binding as well as binding to plasma proteins, may be stereoselecfive. The binding of disopyramide to plasma proteins provides an interesting example of stereoselecfive plasma protein binding and its pharmacokinetic consequences. Both enantiomers of disopyramide exhibit saturable binding to plasma proteins in the therapeutic plasma concentration range. The S(+)enanfiomer binds to cq-acid giycoprotein with a higher affinity than the R(-)- enantiomer. The enanfiomers bind to the same site and therefore may displace one another. This interaction between enanfiomers has important consequences on both the volume of distribution and clearance of disopyramide. In comparison to the R(+)-enantiomer, S(-)propranolol, the more pharmacologically active enanfiomer, binds stereoselecfively to al-acid glycoprotein whereas the R(+)-enantiomer binds selectively to albumin. The binding of fimolol to specific binding sites in myocardium is stereoselecfive. The stereoselective tissue binding of fimolol may result in a longer half-life of the (-)-enanfiomer.

STEREOCHEMICAL ASPECTS OF DRUG DISPOSITION AND ACTION. THERAPEUTIC AND REGULATORY IMPLICATIONS. K. M. Williams Frequently there are both pharmacokinetic and pharmacodynamic differences between enantiomers, a reflection of the asymmetric environment of the biochemical milieu. It can only be concluded that the ideal is to administer enantiomerically pure drugs. It has been cost effective and therapeutically advantageous to do so in some cases (eg. penicillamine, dopa, levamisole) and there are data to suggest that the therapeutic index of other racemic drugs (eg. ketamine) might be significantly increased if the eutomer were employed. Choice of which enantiomer should be used is not necessarily obvious and development of the less appropriate enantiomer has occurred (eg. Stimolol for glaucoma). The rationale for the resolution of other racemates (eg. thalidomide, practolol, warfarin, ibuprofen) remains speculative and may not be cost effective. A limitation of the possibility of separating efficacy from toxicity by use of pure enantiomers is that toxicity is frequently an extension of the desired therapeutic effect of the drug. The rationale to develop an enantiomer over the racemate has not always been based on clear toxicological considerations (eg. naproxen), but even then a satisfactory cost-benefit ratio has been maintained. In exceptional instances (eg. dobutamine), the pharmacological spectrum of activity may be clinically superior for the racemate. A further therapeutic implication of enanfioselective drug disposition is that in order to understand dose or concentration-response relationships, not only should a drug and its active rnetabolites be monitored, but the active enanfiomers must also be measured for meaningful conclusions to be made. Regulatory agencies have not yet clearly formulated their attitudes to ehiral drugs. Future development will see early screening to decide which enantiomer should be developed. It may be advantageous to resolve some existing racemates especially if regulatory agencies do not require extensive preclinical studies on the enanfiomerie form. Development of achiral drugs is one approach to avoid these issues. However, the fact that chirality is integrally and inseparably an aspect of molecular geometry, means that absence of asymmetry cannot necessarily be achieved without a change in activity. Department of Clinical Pharmacology and Toxicology, St. Vincent's Hospital, Sydney, 2010, Australia.

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S 05.02

ESTIMATION ON BENEFIT E i g i l l F. Hvidberg

ESTIMATIONOF RISKSOF DRUGS:CLINICALVS PUBLICHEALTHINDICATORSFOR DECISION MAKING. L. Abenbaim. Inserm, Part% and McGill University, Montreal Four different questions are currently asked when faced with an adverse event experienced by a treated patient or a series of patients. The physician will asked: i) ~what is the chance that this event wil! occur again if I use this drug?'. The clinical epidemiologist will be interested rather in: it) 'what proportion of those events in treated patients are in fact attributable to the drug?'. A public health officer would in turn wonder: iii} "how many of such events will be avoided each year in this country if this drug is withdrawn from the market?'. All of them, and the pharmacologist and pharmaco-mpidemiologist as well, will be interested in the following: iv) 'is the adverse event actually caused by the drug?'. Question i) pertains to risk; question ill to etiologic fraction of risk in treated cases; 4uestion iii) to etiologic fraction of risk in the general population;, and question iv) to the actual relative risk, its magnitude and its biological plausibility. This questions can be answered by a subjective, qua!itativm or semiquantitative approach based on expert opinion on the one hand, or by a allquantitative methodology using epidemiological data on the other. The keyparameter is the etiologic fraction in treated cases. Not exactly in one treated case, but rather in the population of treated cases. A!gorithws have been developed toqualitativeIy assess this probability when confronted with a limited

Correctly performed, s u f f i c i e n t and c l i n i c a l l y meaningful estimation of the efficacy - starting early in the evaluation of a new drug - is a fundamental prerequisite f o r a useful assessment of the balance between benefits and risks f o r a given drug therapy. Measurements of efficacy, both in absolute terms and in p a r t i c u l a r r e l a t i v e to other therapies of the same disorder, must be carried out within the context of controlled c l i n i c a l t r i a l s . However, the estimation of the o v e r - a l l benefit of a drug goes beyond efficacy studies in the limited sense by including much wider aspects. These are related to the various consequences evoked by both the investigations themselves and by a l a t e r widespread use. The methodologies involved may, therefore, also include epidemiological studies, non-blinded multicentre investigations, and eventually meta-analyses and even retrospective case reviews. Different designs may be u t i l i z e d such as quest i o n a i r e s , q u a l i t y of l i f e studies and longitudinal observations of single or few patients. The investigational cornerstone must, however, s t i l i be the randomized c l i n i cal t r i a l , as many of the above mentioned approaches may, in f a c t , produce data of questionable r e l i a b i l i t y and q u a l i t y . The concept of Good Clinical (Research) Practice (GCP) now being widely introduced by the pharmaceutical industry as well as by national and supra-national drug regulatory authorities should, therefore, also be applied to the evaluation of benefits of drug therapies, although GCP requirements are predominantly directed towards the use in new drug applications. The problems of how to estimate the benefit of a particular drug treatment must be viewed from d i f f e r e n t angles related to who may benefit. The patient actually treated must c e r t a i n l y be the f i r s t to be evaluated, but as a l l studies of a new drug contain an inherited advantage f o r the future patients, t h i s must also be considered as a part of the t o t a l estimation. Furthermore, i t should be evaluated which implications a new drug therapy may have f o r the society at large. These could be economic or an influence on the d i s t r i b u t i o n of resources. Other consequences could be a not immediately foreseeable impact on the e n t i r e health care system (e.g. l i p i d lowering drugs) or the influence on the ecology/environment (e.g. antimicrobial drugs). Finally, i t should not be ignored that new drug investigations are s c i e n t i f i c achievements. The benefits in terms of progress in science and methodologies as well as improvement of knowledge are, therefore, important factors f o r the medical community. The estimation of benefits during drug development and in drug therapy is based on several concepts. By combining data and experience from d i f f e r e n t sources and approaches i t should be possible - f o r a given drug therapy - to establish a basis f o r a relevant, r e a l i s t i c and broadly based estimation of the b e n e f i t / r i s k balance. In turn this may lead to a more appropriate medical care policy f o r the f i e l d in question. Rigshospitalet, Clinical Pharmacology, 9 Blegdamsvej, 2100 Copenhagen, Denmark

numberof adverseevents. The bayesian approach is aimed at quantifyingthis probability within the same framework of thinking. What epideeio!ogy can do is to

provide with either the baselinerisk of a givenpathology in the contemplated populatien and the excess risk attributable to the drug (real cohort studies) or

only an approximationof the relative risk in treatedpatients via the oddsratio (case-control studies). With the baseline risk on the one hand and the relative risk or the odds ratio on the other, onecan cuepote al! the risk indicators listed above fit)to iv)]. Data from epideeio!ogical studies can of course be used for a bayesian assessment. On the other hand~ the probabilities derived from a

subjective appraisal can be of valuefor 'roughand ready' answersto questions il to iv) in a context of emergencyor crisis. It will be shown that~ whatever the magnitude of the relative risk, two parametersare only necessary for most decisions to be taken in mothcontexts: the base!inerisk of the problemand the estimation of the proportionof casesactually treated by the drug. Many questions still have to be answered by pharmacologists, epidemiologists, biostatisticiansand public health scientists, such am: I) how

should the risk be expressed?per personstreated? per year?per treatment?per inhabitants? per defineddaily doses? 2) How does the hazard function look like? ~) what 'windown of exposureshouldweconsiderfor risk assessment?

S 05.03 BALANCING BENEFITS AND RISKS: A SCIENTIFIC APPROACH TO THE ISSUES W.O. Spitzer Classically, the measurement of benefits and risks follows the following pattern: in t h e pre-marketing p h a s e of d r u g d e v e l o p m e n t the emphasis is o n m e a s u r i n g benefit, t h a t is efficacy and effectiveness with phase III randomized controlled clinical trials. Once a d r u g is m a r k e t e d , the emphasis shifts to almost an exclusive focus on risk or harm of drugs occurring after a new pharmaceutical is approved by regulatory authorities and released to the markets. This paper concentrates on scientifically admissible attempts to balance distortions in the comparison of b e n e f i t s and r i s k s of d r u g s . In t h e p r e - m a r k e t i n g phase it is n e c e s s a r y to concentrate much more on quali t y of s u r v i v a l than on length of s u r v i v a l (or surrogates of m o r t a l i t y ) by creating and validating measures of q u a l i t y of life which are rigorous and acceptable to clinicians and to the public. In t h e p o s t - m a r k e t i n g phase i t is necessary to move away from heavy dependence on evidence about harm or risk of post-marketi n g d r u g s as t h e o n l y c r i t e r i o n for retaining or banning a drug or for modifying the terms of r e f e r e n c e of i t s a p p r o v e d use in drastic ways. The newly-created Quality of L i f e (QL Index) will be presented as a reliable means of m e a s u r i n g this new dimension both in clinical trials a n d in p o s t - m a r k e t i n g surveillance. Other measures of b e n e f i t will be discussed briefly in a c o n t e x t u a l sense. A research agenda for the future will be outlined. McGill University, Department of E p i d e m i o l o g y and Biostatistics, Purvis Hall, 1020 Pine Ave. West, Montreal (Quebec) H3A IA2

A 11

S 06.01

S 06.02

CLINICAL STUDIES ON DICHROINE-B, Q I N G H A O S U AND ITS D E R I V A T I V E S Guo-Qiao Li A c c o r d i n g to the records of traditional chinese m e d i c i n e d o c u m e n t s , m o r e than 30 herbal remedies were used in t r e a t i n g m a l a r i a but m o d e r n scientific studies have proved that o n l y d l c h r o a and a r t e m i s i a are r e a l l y effective schizontocides. D i c h r o i n e - A , B and C were extracted from d i c h r o a febrifuga. Of the t h r e e , d i c h r o i n e - B is the more potent one. On t r e a t m e n t a total dose of 1 2 mg was given orally over 3 days and was sufficient to control the symptoms and clear the parasites. In terms of side-effects, v o m i t i n g was the only serious complication. In the treatment of chloroquine resistant falciparum m a l a r i a i n C h l n a , q l n g h a o s u and its d e r i v a t i v e s have been u s e d since 1979. ~olerance trials and dose findings of q i n g h a o s u suppository, artesunate and a r t e m e t h e r showed that the good t o l e r a n c e and good therapeutic dose of q i n g h a o s u suppository, artesunate and artemether were 112 mg and 56 mg/kg/5 days, 15 mg and 4.8 mg/kg/Sd, 12 mg and 9.6 m g / k g / 5 d respectively. Qinghaosu suppository in a dosage of 56 m g / k g given over 3 days in divided doses cured 555 of 358 patients with falciparum m a l a r i a and 105 patients w i t h v i v a x malaria. Two falclparum patients developed diarrhoea and changed to a l t e r n a t i v e treatment. Patients with f a l c l p a r u m m a l a r i a became afebrile in 14.9-38.9 hours and cleared parasitaemia in 35.5-52.8 h. ~he r e l a p s e rate was 45.8% in 83 patients followed for 4 weeks. In 42 severe falcipsrum malaria patients, 24 w i t h cerebral malaria, 40 patients w e r e cured and 2 died. Sodium a r t e s u n a t e given i.v. as 4.8 m g / k g in d i v i d e d doses over 3 days cured 258 and 55 falciparum and v i v a x m a l a r i a patients respectively, for f a l c i p a r u m m a l a r i a the patients became afebrile in 14.6-25.3 h and p a r a s i t a e m i a cleared in 34.1-56.4 h. Recrudescence occurred in 49.4% of 89 patients followed up. In 40 patients with cerebral malaria. 95.0% were cured with 2 deaths. Artemether given i.m. as 9.6 m g / k g in divided doses over 5 days cured all 307 f a l c i p a r u m m a l a r i a patients. T e m p e r a t u r e became normal in 21.1-29.7 h and parasites cleared in 31.9-76.2 h. Of 253 patients followed up, 6.7% relapsed. Of 27 cerebral m a l a r i a patients, 96.3% were cured and there was I death. Special studies to m e a s u r e 95% clearance time showed that this was achieved in 16 hours with artesunate, 20 h with artemether, 24 hours with q i n g h a o s u suppository, and 28 hours with i.v. quinine. S i d e - e f f e c t s of the s u p p o s i t o r y were transient and self-limlting and consisted of tenesmus (5.9%), abdominal pain (3.1%), and d i a r r h o e a (0.8%). With artemether, 8 of 76 patients (10.5%) had a l o w r e t i c u l o c y t e count on days 3-6 of treatment which returned to normal by days 7-14. No adverse r e a c t i o n s were observed in patients t r e a t e d w i t h artesunate. During the above studies, 11 patients with a h i s t o r y o f previous h a e m o l y s i s and 19 pregnant patients were treated and no adverse effects were observed.

OINSEN6 H.M. Chang T h i s r e v i e w i s based on h u n d r e d s of s c i e n t i f i c p a p e r s on g i n s e n g p u b l i s h e d w o r l d w i d e in t h e l a s t 20 y e a r s . As t h e k i n g of O r t e n t a l h e r b a l drugs since antiquity, ginseng is reputed to r e p l e n i s h v i t a l energy in biphaslc a c t i o n s to r e s t o r e normal m e t a b o l i c f u n c t i o n s and n a t u r a l b a l a n c e s , p a r t i c u l a r l y In t h e aged and d u r i n g c o n v a l e s c e n c e . BOTANY. T h e r e e r e 3 main s p e c i e s of Panax of c o m m e r c i a l

value: the root of P. glnseng is the official ginseng; P_:_. qu!nquefoilum is American ginseng; and P. notoginseng is sanql. Their chemical compositions and usages are related but different. Wild ginseng is expensive and commercial ginseng products are mainly cultivated. CHEMISTRY. Ginseng is characterized by their saponlns (glnsenosides), generally considered as the active components. From the roots and arlal parts of ginseng & congeners, at least 31 glnsenosides have been isolated and their structures identified. Thelr aglycones f a l l into 3 types: (I) protopanaxadiol, (II) protopanaxatrlol and (III) oleanollc acid. ,zl

~21

"" OOR2

The sugar moiety conslsts of glucose, arablnose, xylose & rhamnose. Ginseng may also contain giucosldes of sitosterols & stlgmasterols, polysaccharldes, polypeptldes, Zn, Cu, & Co enzymes, vitamins, volatile oils and organic acids. PHARMACOLOGY. P. ginseng is an "adaptogen" as it manifests both inhlbltory and excitatory actions on endocrine secretion and metabolism; e.g. reducing blood sugar In hyperglycemia but increasing it in hypoglycemia; enhancing pyruvate klnase activity In liver of normal rats but decreasing it in rats fed a high carbohydrate diet. The biphaslc actions may be caused by the opposite effects of individual glnsenosldes. Ginseng can activate the pltuitary-adrena] system and Increase adrenal steroids production possibly via ACTH release. Ginseng itself is not a sex hormone but it can stimulate the release of sex hormones. On the immune system, ginseng enhanced phagocytosis and nonepeclflc immunity. It promoted the natural killer cell activity and induced production of interferon and interleukln-2. Inhibitory effect of ginseng components on lipid peroxldatJon and scavenger action on free radicals may account for its anti-aging effects. Ginseng can promote both mental and physical activities and relieve fatigue; e.g.,prolong the swimming period of mice and improve the learning process of rats. IV injection of glnsenosides exhibited blphasic but predominantly hypotenslve actlon on blood pressure. The vascular effects of dlfferent glnsenosides in different animals were polymorphlc and complicated. Glnsenosides were also shown to have antl-arrhythmlc effects in rats & rabbits. Recently, ginsenosides were demonstrated to protect the heart against myocardial ischemla, infarction and reperfusion injuries in rats, rabbits and dogs. CLINICAL STUDY. Strictly controlled clinical tests on ginseng are few and most cllnleal data are derived from observations on a large population over many years. Good therapeutic results were reported in lOG cases of hypercholesterolemi a. Ginseng could reduce the dose of insulin and prolong the hypoglycemlc effect. Used In combination wlth cancer therapy, ginseng improved the quality of life of most patients. Ginseng is welltolerated when taken orally. Its acute toxicity is low but varies with individual glnsenosldes. HOwever, longterm administration and high doses may produce "Ginseng Abuse Syndrome", such as restless, insomnia, hypertension, skin eruption and morning diarrhea. CONCLUSION. Contemporary scientific studies indicate that the actions of ginseng are not simply placebo effect. More strictly controlled clinical as well as pharmacoklnetlc studies are needed. Chinese Mediclnal Material Research Centre, The Chinese University of ~ong Kong~ Shatin, Hong Kong,

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S 06.03 GUGGULIPID - THE PROMISING HYPOLIPIDEMIC AGENT FROM GUM GUGGUL (COMMIPHORA MUKUL) G.V. Satyavati

Gum guggul, renowned in the ancient Indian (Ayurvedic) System of Medicine for its use in arthritic disorders was shown to have promising hypolipidemic property (in addition to lowering the body weight), in 1966. This discovery was based on experimental and clinical studies inspired by a Sanskrit reference in Sushruta Samhita (600 BC), a well known Ayurvedic text. This was followed by nearly 40 experimental studies and clinical trials (open, controlled as also double blind) undertaken by different scientists in various laboratories and hospitals in India, over a period of two decades. The most recent clinical trial (published in 1988) reported the efficacy of gum guggul in lowering the atherogenic lipid fractions with significant rise in the HDL cholesterol in patients of hyperlipidemia. Phytochemically, several pure ketonic steroid compounds have been isolated from gum guggul. Of these, Z-guggulsterone and E-guggulsterone are mainly responsible for the hypolipidemic activity. Limited studies on the mechanism of action of the drug have reported a stimulant action of Z-guggulsterone on the thyroid. In most clinical trials, however, a standardized ethylacetate extract of the plant (containing a mixture of Z and E guggulsterones), known as guggulipid, were employed, because of a more potent action of this extract. Based on consistent work carried out at the Central Drug Research Institute, Lucknow, in 1988, a leading pharmaceutical company of India marketted the drug under the name "Guglip", each tablet containing guggulipid equivalent to 25 mg. of guggulsterones. The drug is claimed to lower serum cholesterol (by 27% ) and triglycerides (by 31% ).

given by i,v. infusion lasting I - 4 h depending on the dose, I,m, and s.c. injection cf CQ can also produoe_1 toxic plasma levels when given in doses above 5 mg kg , Lower doses are therefore given at 8 or 12 hourly intervals to achieve the some total daily dosage as with oral administration. Combinations of antimalarial drugs with different mechanisms of action are extensively used far treatment and prophylaxis. Sulphonamides and tet~ahydrofolate reductase inhibitors potentiate each other's antimalarial effect and fixed dasekge formulations of the two are widely available, T e t r a c y c l i n e or S-P i s g i v e n w i t h QN t o ensure complete p a r a s i t a l o g i c a l clearance when t h e r e i s doubt about full sensitivity to QN, It,s also generally believed that combination of one antimalarial e.g. S-P with another s.g. mefloquine could retard the development of resistance to the latter but this is still subject to proof in man. Therapeutic doses of the commonly used antimalarial drubs are usually well tolerated, Severe toxic effects like hypersensitivity skin raations~ leucapenia and ocular damage after 8--P~ amodiaquine [AQ] and CQ respectively w are associated only with long-term use. Because of this~ it is no longer advisable to prescribe S-P and AQ for prophylaXis, OQ can, but if it is taken for longer than 2 y e a r % then the patient should be monitored carefully f o r r e t i n a l changes and t h e drub withdrawn as soon as any such changes appear, Department o f Pharmacology and T h e r a p e u t i c s , University of I b a d a % Z b a d a % Nigeria.

The problems encountered in clinical trials and standardization of herbal products like gum guggul are discussed.

Indian Council of Medical R~earch, Ansari Nagar, New Delhi-110029. INDIA

S 07.01 RATIONAL USE OF ~NTIMAL.ABIAL DRUBS. L.A. Salako The rational use of drugs requires that the right drugs are used for the right indications I in the right doseLg% by the right route, for the right duration. A small variety of drugs are presently available for use in malaria. The choice of drugs in any given situation is determined by factors related to the parasit% to the drug and to the patient. The most important parasite factor is its drug sensitivity. Prominent among the drug factors are availability of apprapriate dosage form~ dosage convenient% speed of a c t i o % tolerability, safety I cast and the drug's pharmacokinatics. The important patient factors ere a g % malaria immunity status, pregnancy~ severity of the infection and presence of complications ~hat could affect the action or disposition of the drug. T h e greatest obstacle to the success of the strategy of malaria control through chemotherapy is resistance of the parasite to the currently available drugs. Resistance of P. faleipsrum (P.f.) to ohloroquine (CQ] and sulphadoxinspyrimethamine (~-P] is widespread and resistance to quinine (QN) is also increasing necessitating the use of varieties of drug combinations in many countries. Because the different plasmodial species differ in their sensitivity to drugs, the choice of drugs is determined by the causative species. In the case of P.f. the severity ef the infection is also important in the choice of drugs, Most antimalarial drugs are available in oral dosage forms and are rapidly and almost completely absorbed from the gut. The oral route is therefore prefarred~ except in the unconscious patient or in the patient who cannot tolerate the drug by this route. Paranteral at~ninistrstion cannot be justified in patients with uncomplicated malaria who can tolerate oral dosing. Recent pharmacokinetie studies on OQ and ON, the two antimalarial drugs commonly given parenterally, have made it possible to rationalise their parenteral use with respect to dose size and frequency. Both drugs are very dangerous by bolus i.v. injection and should only be

S 07.02 DRUG RESISTANCE Hagal glnsburK In spite of many years of extensive use and intensive investigations, the antimalarial mode of action of 4amlnoqufnoline containing drugs is not well understood, let alone the reasons for drug resistance. It is now generally accepted that these drugs accumulate by virtue of their weak base properties i~slde the acid food vacuole of the intraerythrocytlc malarial parasite, the organelle by means of which the parasite digests the cytosol of its host cell. Chloroquine (CQ)-susceptible parasites accumulate more drug than their drug-reslstant congeners and have a v a c u o l a r pH that is more acid than that of drug resistant parasites. Since the pH of the food vacuole is determined by an ATP-drlven proton pump acting in parallel w i t h e proton back-flttx, drug resistance could result either from reduced pump activity or/and increased ~+-efflux. Preliminary results indicate that the latter is one order of magnitude slower in CQ-sensltlve strains of Plasmodium falclparum. Unlike the lysosomotroplc effect of CQ in mammalian cells which results in the alkallnization of the intraeellular acid compartment, antimalarial drugs do not alkalinize the parasite's food vacuole at therapeutic concentrations, suggesting that they interfere with the enzymatic steps of the feeding process. Preliminary results show indeed that parasite acid phosphollpases are inhibited by the expected vacuolar concentrations of CO, quinine and mefloquine. The antimalarial action of CQ is time-dependent and becomes maximal and irreversible after 4 hrs of exposure, eoncomittant with a fraction of cellular CQ whlch cannot be removed. The llgand and affected target(s) have not been identified yet. Recent results suggest that drug resistance can be reversed by a wide spectrum of pharmacologically unrelated compounds, which are also known to reverse drug resistance in cancer cells and a similar mechanism of action has been inferred. The precise mode of action and the efficacy of drug combination in vivo remains to be established, but there is no doubt that the phenomenologlcal observations constitute a basis for a true revolution in the

A13

chemotherapy of malaria. In recent years, other chemotheraeutic approaches have been advanced, based on a deeper understanding of the physiology and biochemistry of the parasite and its interaction with the host erythrocyte. Thus, new targets such as the biosynthetic pathways of polyamines and pyrlmldlnes or hlomolecules susceptible to oxidative stress, have been identified and their inhibition by selective and relatively specific inhlbltors has been demonstrated. Nevertheless, even such novel targets are prone to become drug resistant. One possible way to circumvent s~ch evolution could be the choice of host cell targets rather than parasite ones. Such selection is based on the reasoning that variant erythroeytes, such as sickle or G6PD-defielent cells, are refractory to parasites. Generally, the blochemlstry and physiology of these red cells are widely and significantly different from those of normal cells and the probability that the parasite will evolve to adapt to the "hostile" environment provided by these cells, is close to nil. Nence, use of antimetabolltes which would mlmick the biochemical alterations found in variant red cells, should inhibit parasite development" without the eventual appearance of drug resistance. The targeting of new antimalarials into infected cells can be achieved using the recently acquired knowledge on the new permeability pathways which the parasite induces in the membrane of its host erythrocyte. These pathways are indispensable for the adequate supply of metabolites to the parasite and for the discharge of its waste products, and their blockage by bioflavonoids demonstrably leads to parasite death. Since the selectivity properties of these pathways are not matched by those of any other type of sommatlc cell, they can be used to deliver drugs specifically into malaria-infected cells, as has been shown for example for the Case of metal chelators. This approach can be further improved by the identification of parasite enzymes which could activate otherwise non-toxlc precursors of targeted drugs. Department of Biological Chemistry, Institute of Life Sciences. The Hebrew University. Jerusalem 91904, ISRAEL.

At present) %he most es regimen for treatment of m u ] t i r e s i s t a n t m a l a r i a is Q7T7. A m o r e c o n v e n i e n t r e g i m e n w o u l d be 2 tablets of 2 5 0 m g M or M S P at 6 h o u r s i n t e r v a l a n o t h e r 2 tab. at 6 h o u r s i n t e r v a l t h e n 1 tab. for p a t i e n t w i t h b o d y w e i g h t o v e r 55 or 2 t a b for o v e r 65 kg.

S 07.03

S 07.04

DRUG COMBINATIONS FOR TREATMENT AND PROPHYLAXIS OF MULTIRESISTANT MALARIA

CLINICAL EVALUATION OF MALARIA VACCINES D. St0rch.le,r Targets of P. f@,lcibarum vaccine development are preerythrocycic forms (sporozoites, liver schizonts), asexual blood forms (free merozo tes, b ood schizonts) and sexual forms (gametes, zygote). Phase I clinical evaluation is the same for the three groups of vaccine candidates, with safety and immunogenicity as the principal objectives. In the absence of surrogate measurements of protectivity, efficacy of sporozoite vaccines is determined in phase II by experimental P.~. falciparu~ infection of non-immune volunteers carried by laboratory reared Anopheles mosquitoes fed on gametocytes in culture. In this way, recombinant and synthetic sporozoite vaccines derived from the repeat portion of the circumsporozoite protein have been tested; protectivity by the two types of vaccine was 1/6 (17%, WR Ballou et al Lancet i, 1277, 1987) and 1/3 (33%, DA Herrington et al Nature 328_, 257, 1987), respectively. The procedure is safe provided that participants are reliable and knowledgeable, low levels of parasitemia are readily recognized, and a drug sensitive P. falciparum strain is used.

D. B u n n a g

and T . H a r i n a s u t a

The m o n i t o r i n g of t h e e f f i c a c y of a n t i m a l a r i a l d r u g s on f a l c i p a r u m m a l a r i a and c h e m o t h e r a p e u tic t r i a l s h a v e b e e n c a r r i e d out since 1975 at the Bangkok H o s p i t a l for T r o p i c a l Diseases. Chloroquine(C), Sulfadoxine-Pyrimethamine (SP) and quinine(Q) have cure rates which dropped f r o m 15 to 0 % in 1979 & 81, 35 to 6 % in 1979 & 80,and 94 to 73 % in 1979 & 87 respectively(l). Mefloquine (M) and the combination of Mefloquine-SulfadoxinePyrimethamine (MSP) w h i c h has an e f f i c a c y of i00 & 9 8 % in 1980 & 83 r a p i d l y d r o p p e d to 86 a n d 8 1 % in 1 9 8 5 ( 2 , 3 ) .

When t e t r a c y c l i n e l g d a i l y in 4 d i v i d e d doses for 7 d a y s was u s e d in c o m b i n a t i o n with C l.bg, SP 3 t a b l e t s a n d q u i n i n e s u l f a t e 500 mg base e v e r y 8 h o u r s for 5-7 days (Q5TT,QTTT) much h i g h e r cure r a t e s of 75 & 8 6 % in 1982 & 84, 75 & 8 6 % in 1982 & 84, 88 & 1 0 0 % in 1987 & B8 were obtained respectively (1,3). Cinchonism was frequent in the groups r e c e i v i n g Q 5 T 7 and Q T T 7 but t h e y w e r e m i l d and transient. The a d v e r s e e f f e c t s of M and M S P were also m i l d and transient and included n a u s e a and v o m i t i n g (20%) , w e a k n e s s ~ isomnia, pruritus and skin rashes, neuropsychiatric reaction (1%) and asymptomatic sinus bradycardia (30%) n o n e of w h i c h r e q u i r e d no specific treatment. Either M o r - M S P is e f f e c t i v e for prophylaxis of m a l a r i a w h e n M 1 2 5 mg weekly .~a&.~iven w i t h l o a d i n g d o s e s of 2 5 0 m g for the f i r s t 4 w e e k s . The side e f f e c t s in 2 B - d S ~ of s u b j e c t s wel-e mild and twa~sient &~d Rot significanthy d i f f e r e n t f r o m those of the p l a c e b o gYoup.

~eferences i. Bunnag,D., & Harinasuta,T. (1987). J. P a r a s i t o l 169-180. 2. H a r i n a s u t a , T . , & Bunnag,D. (1987). WHO 363-367. 3. Internal Reports 1987&1988.

Int. Bull.

Department of C l i n i c a l T r o p i c a l M e d i c i n e and B a n g k o k H o s p i t a l for T r o p i c a l D i s e a s e s , F a c u l t y of T r o p i c a l M e d i c i n e , Mahidol University,Bangkok 10400,Thailand.

S u p p o r t e d in p a r t s b y UNDP, W o r l d Bank, WHOTDR Programme and F.Hoffmann-La Roche, Switzerland.

Testing of asexual blood stage vaccines is more difficult. Intravenous challenge with infected red blood cells was performed in 13 volunteer soldiers of the Colombian military forces. In order to determine efficacy, parasitemias were allowed to build up to levels >0.5% and to persist untreated for severat days (ME Patarroyo et al Nature 332, 158, 1988). This procedure, used in the past for treatment of neurosyphilis, is not universally accepted. In the absence of WHO guidelines, alternatives for efficacy

A 14 Cont. S 07.04 testing of blood stage vaccines include: mosquito borne challenge infection in vaccinees receiwng the blood sta~e vaccine candidate plus a sporozoite vaccine e~ther in combination or in concurrent administration, or natural infection in well-defined field studies. Safety and immunogenicity, but not efficacy is required to demonstrate for vaccines against sexual forms of P. falciDarum. Sexual stage vaccines raise an ethical probleminsofar as the vaccinee does not draw immediate benefit from immunization. Hoffmann - La Roche PKFfTI, Postfach, 4002 Basel, Switzerland.

Tx it app@ars p o s s i b l e i n 60-75 % of c a s e s to achieve ~$n~le drug (SIM) maintenance therapy after 6 months. To any such schedule belongs careful monitoring of blood levels using the Sandimmun-Kit containing specific Mabs to measure unchanged drug. Using whole blood one avoids the problem of time and temperature dependency which affects plasma/serum measurements. At the same time one must remain aware of interactions which can cause increase/decrease in CS concs. In renal Tx SIM has improved graft survival by some 15-20 % in comparison with conventional therapy so that 5-year actuarial graft survival is now about 60 %. Liver and heart Tx have become routine with actuarial 5-year survival of about 60 % and 80 %, respectively, whereas heart-lung Tx still lags behind with a 2-year actuarial survival of about 60 %. Side effects are similar in all ~ndications and, apart from the general risks of I/S therapy (infection & malignancy), include reversible impairment of renal function, nephrotoxicity (with histological changes), paraesthesia, hypertrichosis, GI symptoms, gingival hyperplasia, hypertension and tremor. SIM has become established in Tx and offers great promise in a number of autoim/nune diseases where the risk/benefit ratio r e q u i r e s m o r e careful consideration. Overall, the steroid-sparing effect of SIM is probably one of its main attractions in both Tx and autoimmune diseases. Combination therapy, already used successfully in TX, may lead to still further benefits in autoimmune diseases but one has still to decide on which combination, when to use it, in what doses and for how long. SIM has achieved such widespread usage by being the prototype of a new class of I/S agents. R = Registered Trade Mark Clinical Research, Sandoz Ltd., CH-4002 Basle, Switzerland

S 08.01

S 08.02

THERAPEUTIC USE OF IMMUNOMODULATORS: SANDIMMUNR (SIM), cyclosporin) - THE FIRST iO YEARS T. Beveridge Cyclosporin (CS) is a cyclic polypeptide of mol. wt. 1203, containing ii amino acids and derived from the fungus Tolypocladium inflatum Gams. It is a potent immunosuppressive (I/S) a g e n t w h i c h , unlike traditional I/S agents, acts specifically and reversibly on lymphocytes. CS is neither cytotoxic nor myelosuppressive and has no effect on the function of phagocytic cells, ~hus preserving the host's d e f e n c e a g a i n s t infection. Whilst the exact mode of action of CS is not known its I/S effect is thought to relate to its ability to inhibit the production of interleukin-2 (IL-2) and other lymphokines (e.g. y-interferon) by actfvated T-lymphocytes (mainly T-helper cells). The inhibition of lymphokine synthesis by CS is the result of its action at the nuclear level where it prevents the transcription of mRNA for IL-2. As a result of these effects, CS is effective in both the experimental animal and man in preventing the immune response to ailoantigen following organ transplantation (Tx), and in diminishing the response to autologous antigens in autoi/amunity. In man, SIM has been used successfully in kidney, liver, heart, heart-lung, lung, pancreas, cornea, small bowel, skin and bone marrow TX. In autoin~nune diseases many clinical studies have shown that SIM is effective, so it s~ems certain that it will be used increasingly as an alternative to other I/S agents in severe cases of endogenous uveitis, rheumatoid arthritis (RA), some forms of nephrotic syndrome, severe generalised psoriasis, systemic lupus erythematosus (SLE), Crohn's disease and various other autoimmune diseases. Although it is now more than iO years since SIM was first used in clinical Tx there is still no consensus about its optimal use. The general aim is always to profit from the efficacy of SIM while using it in a way that will minimise its side effects. Thus, SIM can be given alone, along with steroids or as part of a triple or quadruple drug regimen. In renal

ihe Interferon Systom: KIRCHNER, H. Institute of Immunology and Transfusion Medicine, University of LUbeck, Med. School The interferon system is an integral part of the defense system of the body mediating a large variety of biologic effects. Presently, three groups of interferons (IFN) are kno~q: IFN ~ , IFNB and IFNaV'. IFN~ and IFNB show homolo&v on the nucleotide level of about 40-50~/~, and both IFNs bind to a COnTnonreceptor. IFN ~ and IFNB are produced after induction by leucocytes and fibroblasts. IFN ~,~ is, by definition, not only an interferon but also a lymphokine,- since i t is a product exclusively of lymphooytes. There is no homoloc~von the nucleotide level between IFN~ and IFN ~/B. Furthermere, the receptor of IFNa~ is different from tee receptor of IF-N~C/B. IFNs age defined by their antiviral activity against a large nun/oer of different viruses. The target of IFN is the cell rather than the virus itself. Through binding at the cell surface and subsequent activation of specific genes IFNs induce an antiviral state which makes cells less permissive for virus replication. The antiviral state consists of various antiviral mechanisms. /~mong the non-antiviral effects of IFNs are effects on cellular components of the immune system. Thus, one has postulated a role for interferons as inmunoregulatory molecules. Interferons augment the expression of NHC-genes of which IFN /B only affect the molecules of class I, whereas IFN affects both the molecules of class I and class II. Moreover, all IFNs increase the activity of macrophages and NK cells. Possibly, the activation of conloonentsof the inTnune system is in part responsible for the antitumer effects of interferon. In a few instances interferon is active in cancer therapy. Promissing reports have appeared on the use of IFN in hairy cell leukE~nia, Kaposi's sarcoma, non-Hodgkin's ljanphoma, and melanoma. Until now, IFN-therapy has failed to be successful for the treatment of cancers such as bronchial carcinoma, breast or colon cancer. In clinical trials, IFN therapy was useful in diseases caused by different viruses, i.e., papilloma viruses (laryngeal papillomas), herpes viruses (herpes keratitis), and hepatitis B virus.

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S 09.02

M. A. S. Moore Abstract not received by April 30, 1989

CUTANEOUS SIDE EFFECTS OF SYSTEMIC DRUGS AND THEIR MECHANISM OF ACTION J. A. A. Hunter i. Epidemiology of drug eruptions. 2. Drugs which commonly cause cutaneous reactions (include penicillins, su/phonamides, cephalosporins he_nzodiazepines, thiazide diuretics and allopurinol). 3. Drugs which very rarely cause cutaneous reactions (include digoxin, potassium and iron preparations and vitamins). 4. Classification, mechanisms and some examples of

drug eruptions: Non-immunological a)

b)

reactions (more than 80% of drug eruptions) Direct toxic reactions Overdosage: blisters~barbiturates Predictable side effect: alopec_ia/cytotoxic drugs Idiosyncratic (qualitatively abnormal respons~ variegate porphyria/oestrogens Intolerance (exaggerated normal response): haemorrhage/methotrexate Phototoxicity: exaggerated sunburn reaction/ thiazidediuretics Accumulation: pigmentation/chlorpromazine Tumour induction: arsenic/skin malignancies

Indirect toxic reactions Release of inflammatory mediators: aspirin/ urticaria Exacerbation of skin disease: psoriasis/ B-blockers Drug interactions: haemorrhage/methotrexateaspirin Ecological imbalance: dermatophyte infections/ steroids Tumour induction: azathioprine/HPV-squamous cell

carcinoma

S 09.01 QUANTIFICATION IN DERMATOPHARMACOLC~ H. I. Maibach In recent decades many advances in dermatopharmacology evolved as "spin-offs" of development in general pharmacology with structural or delivery system modifications for Skin (e.g., corticoids, antifungals, 5FU, antibacterials and pesticides). At least one resulted from an individual scientist's conceptual curiosity (isotretinoin). The skin presents a variegated, puzzling, complex yet fascinating opportunity to perform quantitative bioassays that might yield new pharmacologic agents. This presentation will describe the mentation and technology involved. Examples will include: corticoid perturbations in protein formation, retinoid alterations in hyaluranate accumulation, skin blood flow related to hair growth and delivery of drugs into skin rather than through skin.

Immunolc~ical reactions (the great minority) ~ype I: Anaphylactic type - igE mediated: urticaria/ penicillin Type III: Arthus type - circulating immune complexes: vasculitis/thiazide diuretics Type IV: Delayed type hypersensitivity lymphocyte mediated: eczematous rashes/ penicillins 5. Some characteristic (but not specific) eruptions Pemphigus-like: D-penicillamine Psoriasiform: Practolol Lichenoid: Gold Photosensitive-bullous: Nal• Acid Multiple skin tumours: Arsenic Erythema multiforme: Sulphonamides Fixed drug eruption: Phenolphthalein Anqioedema: AsPirin Maculopapular rash: Ampieillin/infectious mononucleosis Skin necrosis: Warfarin Lupus erythematous-like: Bydralazine Toxic epidermal necrolysis: Phenylbutazone Mypertrichosis: Minoxidil 6. Diagnosis a) History: Temporal relationship b~ Discontinuation of drug: Flaws and drawbacks c) Provocation with drug: Ethical considerations d) Skin tests: Patch and prick testing e) In vitro tests: RAST: Basophil d~ranulation test. Lymphocyte transformation test 7. Useful References Bork K: Cutaneous side effects of drugs. W.B. Saunders Company, Philadelphia 1988. Bruinsma W: A guide to drug eruptions. 4th Edition 1987. University Department of Dcrmato/c~qy, qhe Royal infirmary, Edinburgh EH3 9YW Scot/and.

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S 10.01

S 09.03 DRUGS AND THEIR A C I I O N

ON THE EYE

O. Hockwin~ U. M ~ l l e r - B r e i t e n k a m p and A. Wegener The eye is an highly s p e c i a l i z e d , very s e n s i t i v e and well o r g a n i z e d organ of sense~ r e a c t i n g immed i a t e l y to s t r u c t u r a l and f u n c t i o n a l d i s t u r b a n ces, r e a l i z e d by the p a t i e n t as s u b j e c t i v e visual i m p a i r m e n t . The eye r e p r e s e n t s a c o m b i n a t i o n of nearly all kinds of tissue s t r u c t u r e s like s t r i a t e d and smooth muscles, sinews, s e c r e t i o n organs, p e r m e a b l e and s e m i - p e r m e a b E e m e m b r a n e s as well as p r o n o u n c e d p i g m e n t layers. B e s i d e s tissues with a high blood supply like retina and c h o r o i d e a it c o n t a i n s c o m p a r t m e n t s w i t h o u t direct c o n n e c t i o n to b l o o d (and nerve) s y s t e m where e x c h a n g e of matter is c o n t r o l l e d by blood b a r r i e r functions. As the only organ of the body it has in order to fulfill its main ruction - tissues and fluids with t r a n s m i s s i o n of the v i s b i l e light. The m a i n t e n a n c e of the t r a n s p a r e n c y is based on normal m e t a b o l i c c o n d i t i o n s . A n a t o m y and function of the entire eye allow direct e x a m i n a t i o n by n o n - i n v a s i v e m e t h o d s and d e s c r i p t i o n / d o c u m e n t a t i o n of p a t h o l o g i c changes in m o r p h o l o g y . Last not least, the p a i r w i s e a r r a n g e m e n t of the eyes allow direct c o m p a r i s o n ( b i o l o g i c a l twins) of t r e a t e d with u n t r e a t e d control eye in p h a r m a c o k i n e t i c a l and t o x i c o l o gical s t u d i e s i n - v i t r o as well as in-vivo. In a n a l y s i n g the m a n i f e s t a t i o n of d r u g - i n d u c e d c h a n g e s or d i s e a s e s of the eye we have to d i f f e r e n t i a t e b e t w e e n i. local side e f f e c t s after topical a p p l i c a t i o n of o p h t h a l m i c drugs, 2. local side e f f e c t s after s y s t e m i c a p p l i c a t i o n of drugs (mostly n o n - o p h t h a l m i c s ) as well as 3. s y s t e m i c side effects after topical a p p l i c a t i o n of o p h t h a l m i c drugs. Based on c l i n i c a l o b s e r v a t i o n s and e x p e r i m e n t a l results, d e t a i l e d l i t e r a t u r e reviews and m o n o g r a p h i e s c o v e r i n g a great number of d r u g - i n d u c e d ocular c h a n g e s are now available. E x a m i n a t i o n s of ocular t o x i c o l o g y in c h r o n i c drug t o x i c i t y s t u d i e s have not yet r e a c h e d the s t a n d a r d w h i c h is in a c c o r d a n c e with the present k n o w l e d g e of o p h t h a l m i c science. Main p r o b l e m s arise by the use of n o n - p i g m e n t e d (albino) animals. E v a l u a t i o n s with respect to the (pigmented) human eye are almost i m p o s s i b l e . There is still nearly a c o m p l e t e lack of ocular p h a r m a c o k i n e t i c m e a s u r e m e n t s . Such d i s t r i b u t i o n studies have to be i n t r o d u c e d at least for all drugs of i n t e n d e d longer t h e r a p e u t i c a l a p p l i c a tion. For d o c u m e n t a t i o n i n s t r u m e n t s with i n t e g r a t e d photo e q u i p m e n t (photo s l i t - l a m p , fundus camera, S c h e i m p f l u g photo system) should be used. For s p e c i a l p r o b l e m s a v a r i e t y of m e t h o d s may be applied. - A t t e n t i o n must be payed to m u l t i f a c t o r i a l origin of lens o p a c i f i c a t i o n in human of old age. A c o i n c i d e n c e of several factors - among them d r u g s - which need not be d i r e c t l y c a t a r a c t o g e n i c , but may act as s u b l i m i n a l (or p r o m o t i n g ) factors, r e q u e s t a special test p r o c e d u r e . Animal models to test the c o c a t a r a c t o g e n i c p o t e n t i a l of drugs are now available. The h i a t o p a t h o l o g y of the lens does not c o n t r i b u t e at all to e l a b o r a t e the s u b l i m i n a l d a m a g i n g m e c h a n i s m , it is almost o b s o l e t e as an i n d i c a t o r and should not longer be r e q u e s t e d by g o v e r n m e n t a l drug offices. It should be replaced, w h e r e n e c e s s a r y , with p o s t - m o r t e m a n a l y s e s of b i o c h e m i c a l lens p a f a m e t e r s being a more s e n s i t i v e i n d i c a t o r even for s u b l i m i n a l e f f e c t s which did not yet affect the lens t r a n s p a r e n c y . M e t h o d s and e x p e r i e n c e s are today a v a i l a b l e that the eye needs no longer to be among the n e g l e c t e d o r g a n s of drug r e s e a r c h and their c l i n i c a l a p p l i c a t i o n . A b t e i l u n g f~r e x p e r i m e n t e l l e O p h t h a l m o l o g i e der U n i v e r s i t ~ t Bonn, S i g m u n d - F r e u d - S t r . 25, D-5300 BONN 1

THERAPEUTIC STRATEGIES A N D GOALS R. Gugler Healing of acute gastric and duodenal ulceration is achieved with a variety of different drugs representing three major mechanisms of action: acid neutralization, inhibition of acid secretion, mucosal protection. Most drugs heal 70 to 90 % of ulcers within four weeks with some variation in the 2 week healing rates. Symptom relief is seen within one week in the majority of patients. Of all factors "which might influence individual ulcer healing only smoking has been uniformly identified to be associated with the incidence of duodenal ulcer and a delay in ulcer healing, while age, ulcer history or socio-economic factors play a role only in some studies.Antacid therapy is found to be effective even in small dosis of 200 mmol neutralization capacity per day suggesting that effects other than acid neutralization are present such as mucosal procetion. H2-receptor antagonists to date dominate the peptic ulcer treatment, whereas the clinical significance of longer and more effective acid inhibition by H / K - A T P a s e inhibitors remains to be established. The prostaglandins might find their place in the treatment and prophylaxis of lesions caused by nonsteroidal antiinflammatory drugs rather than in common ulcer therapy. As 25 % of duodenal ulcer patients have 2 or more ulcers per year, definition of strategies to treat the chronic ulcer is the primary challenge today. Prevention of ulcer relapse and of ulcer complication are the goals in chronic treatment. Intermittent treatment is designed to give the patient a full course of therapy for any new ulcer. With this strategy the incidence of complications (perforation, bleeding, stenosis) is not reduced as shown by a constant rate of ulcer surgery. Long term prophylaxis by H2-receptor antagonists effectively reduces ulcer relapse rates, but does not chance the natural history of the disease as seen by high relapse rates after stopping maintenance treatment. Ulcer surgery is performed less frequently today in the presence of potent drugs which have a minimum of side effects. Even after highly selective vagotomy ulcer relapse rates of up to 2o % over 5 years show that the disease is not cured by the operation. For the duodenal ulcer patient with a high relapse rate in a given time maintenance treatment is the recommended strategy, but surgery is necessary in treatment failure, in the case of complications or if the patient is noncompliant to the medical treatment.

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S 10.02 USE OF INHIBITORS OF ACID SECRETION IN ULCER THERAPY A.L. Blum S e c r e t o r y inhibitors are used both in gastric ulcer and in duodenal ulcer, in the former in spite of normal or low acid secretion and, in the latter, in spite of an important pathophysiological role of C a m p y l o b a c t e r pylori. Thus, the basic idea of secretory inhibition is not to normalize e l e v a t e d acid secretion but to shift the balance of multipte pathophysiological factors in favor of repair of the present ulcer and protection from the next attack. The clinical effectiveness of acid inhibitors is proportional to their reduction of acid secretion; nocturnal inhibition appears to be more important than inhibition during the day. The strongest presently known secretory inhibitor, omeprazole, yields the best healing rates. At present, two differing views are expressed: t r a d i t i o n a l i s t s s e t t l e for the inferior healing r a t e of histamine H2 antagonists to avoid h y p e r g a s t r i n e m i a and its consequences at all costs; in contrast, maximalists think that the drug which yiehls the _fastest healing rates is the best, Histamine H2 antagonists are given once a day; a theoretical advantage o[ giving them w i t h dinner, instead of late in the evening, is not c l i n i c a l l y relevant. In order to assess to optimal length of t r e a t m e n t , we performed a prospective study in 2109 patients w i t h duodenal ulcer t r e a t e d with ranitidine. Healing was delayed in patients with smoking, large ulcers, m u l t i p l e ulcers, a history of slow healing and complications and in those who were unemployed. When more than two of these risk factors are present, t r e a t m e n t should last for more than # weeks. Maintenance t r e a t m e n t with secretory inhibitors markedly decreases the recurrence rate. Risk factors indicating t h a t recurrences may occur in spite of maintenance t r e a t m e n t are heavy physical work, psychological stress, smoking, duodenitis, persisting pain a f t e r healing, m u l t i p l e ulcers, a long ulcer history and certain geographical factors such as a habitat in the northern part of Germany. Gastroenterologie, CHUV, C H 1 0 l l Lausanne

Some antiulcer drugs, which are believed to act primarily by neutralization of gastric acid (antacids) or by coating the mucosa (Sucralfate, Oe-Nol), have been reported to exhibit gastroprotective properties both in animals and humans against various irritants (aspirin-like drugs, bile acids, ethanol or stress) partly due to the stimulation of mucosal production of PG. Although there is little doubt that PG, especially their stable methylated analogs and drugs such sucralfate or Oe-Nol exhibit remarkable gastroprotective properties, it is not clear whether such protection could offer any clinical benefit in the therapy of peptic ulcer and whether gastro-protective drugs are superior to ulcer healing properties of "classic" antiulcer gastric inhibitory agents such as H2-receptor antagonists or anticholinergics. Recent clinical trials with various methylated PGE analogs revealed that these agents are capable to enhance ulcer healing but only when used in gastric inhibitory doses. In contrast, cytoprotective doses did not affect significantly the healing rate suggesting that cytoprotective properties, which are so dramatic in prevention of acute mucosal damage play little role in ulcer healing. This indicates that the inhibition of acid secretion rather than strengthening of mucosal defence mechanisms plays an important role in promotion of ulcer healing. Positive effects in ulcer healing obtained with sucralfate or De-No] (which do not affect gastric acid secretion) could probably be attributed to the formation by these drugs of physical barrier over ulcerated mucosa to prevent acid-pepsin aggression and to the accumulation in the ulcer area of epidermal growth factor (EGF) which may promote the process of ulcer healing. Institute of Physiology, Medical Academy, ul. Grzegorzecka 16, 31-531 Krakow, Poland.

S 10.03

S 11,01

CYTOPROTECTI~4 S.J. Konturek Gastric mucosa is constantly exposed to various irritants but it usually maintains its integrity due to several lines of defence including mucus-alkaline secretion~ mucosal hyrophobicity, rich mucosal blood flow, stabilization of tissue lysosomes, maintenance of mucosal sulfhydryls and rapid proliferation and renewal of mucosal cells. Prostaglandins (PG) prevent acute gastric mucosal damage and ulcerations induced by a wide variety of agents, hence PG have been originally proposed to contribute to the overall protective process ("direct" cytoprotection) by activation of various mucosal defence lines, particularly, bY prevention of vasocongestion, ischemia and deep hemorrhagic necrosis. The relation between t i s s u e PG g e n e r a t i o n and mucosal p r o t e c t i o n does not appear to be c l o s e l y r e l a t e d and p r o b a b l y only minute amounts of PG are required to maintain mucosal integrity. In contrast to PG, other products of arachidonate metabolism such as TxA2, LTC4 or LTD4 and the related lipid, platelet activating factor (PAF), appear to mediate mucosal damage mainly by the disturbance in mucosal microcircu]ation and tissue ischemia. Gastroprctection can be achieved by stimulation of mucosa] biosynthesis of protective PG or by the inhibition of the release or action of the proulcerogenic arachidonate metabolites. Certain natural substances such as sulfhydryls, epidermal growth factor or po]yamines protect the mucosa via PG-independent mechanism probably by enhancing the tissue repair processes. The resistance of mucosa to injury can be also increased by challenging with mild irritants ("adaptive cytoprotection") and this has been attributed to the stimulation of mucosal PG biosYnthesie but certain role may also be played by physical barrier formed from the alkaline mucoid debris ("mucoid cap") which mitigates the effects of subsequent exposure to the necrotizing agents and allows for rapid epithelial repair and reconstitution.

PRENATAL DRUG TREATMENT. P. VERT

The rapid progress in antenatal diagnosis of an increasing number of diseases and the understanding of some principles of drug transfer across the placenta led to more or less successful attempts of prenatal treatment which remain partly empirical. The bidirectional kinetics through the placenta, volume of distribution, free fractions, metabolism, Te ~ in the fetal compartment are still poorly documented, with increased risks of either inefficacy or toxic effects. The maternofetal ratio of a drug plasma level at a given time (ie birth) does'nt allow extensive conclusions~ Glueocorticoids particularly betamethasone have been widely used to enhance lung maturation and surfactant production by the alveolar type II cells, between 28 and 32 weeks of gestation with controversial results in male infants, Dexamethasone has been successfully prescribed for the prevention of virilization of female fetuses at risk of adrenogenital syndrome due. to 21hydroxylase deficiency. Sustained supraventricular tachycardia, often associated with hydrops fetalis, both diagnosed by sonograph~ has been converted by different drugs : Digoxin, Betablowers (Propanolol), Proeainamide, Calcium channels blockers (Verapamil). Amiodarone containing substantial amounts of iodine may induce a fetal hypothyroidism. Congenital toxoplasmosis can be diagnosed by fetal cord blood sampling. Prenatal treatment with spiramycine is largely used with good beneficial evidences. The sdjunction of Pyrimethamine and Sulfadiazine has recently been proposed. Prenatal treatment has to be considered in the context of fetal development and viability and in a pluridisciplinary approach. Waiting for more knowledge in antenatal pharmacology, the evaluation of benefits and risks must challenge audacity in desperate diseases. Maternit~ R@gionale Universitaire et INSERM U 2?2 54042 Nancy France.

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S 11.02 ANALGESICS IN NEWBORNS? L.O. Bor6us Pain is subjective and our knowledge about it is related to our own experience and interpretation of the stories that others have told. In the newborn infant, a verbal or Other type of symbolic language for the description of the type and intensity of pain cannot be obtained. This does not mean that a cognitive part of the pain in the infant must be missing. But in order to assess pain the observer must resort to interpretation of behavioural or biochemical events following what we believe to be painful stimuli. Motor responses such as facial expression, crying or special leg/ann movements have been interpreted as manifestations of pain in the newborn and scales for quantitative assessment of these reactions have been presented. Alternatively, metabolic, hormonal, or neurophysiological changes that follow nociceptive stimulation have been determined. The basic methodological difficulty is that even if the most sophisticated technique is used in these measurements, the investigator will lack the final proof of the existence of cognitive pain which is the selfreport from the patient. Recent studies in the area suggest that proper analgesia is of advantage to the newborn. Adequate anaesthesia during surgical interventions lightens the stress load on the infant and improves the postoperative course. Thus, pain itself may be harmful and treatment with analgesics may be a more important factor for the results of neonatal care than earlier realized. Remarkably few studies have been made on the usefulnes of analgesics in the newborn. It appears that the methodological difficulties to measure pain and pain relief in this age period is not the only reason. Lack of interest in the problem is also evident. Many procedures that would be inconceivable in the adult without pain alleviation are still often routine in the newborn. Recent reviews have shown that many paediawic anaesthetists have long been reluctant to prescribe analgesics to newborns. The conception that the newborn cannot feel pain is impossible to prove or disprove, Both nociceptive and anti-nociceptive systems are working in the central nervous system and neurological immaturity itself does not necessarily imply that pain cannot be suffered. The negative biochemical and behavioural consequences of nociceptive stimulation are the only signals from the patient for improved pain relief and should be reasons enough to provide the newborn infant with analgesia. Several routine procedures in neonatology are associated with iatrogenic nociceptive stimulation: injections, sampling of body fluids, application of catheters, etc. Birth traumata and postnatal surgery are also causing pain. These situations must be identified and as much as possible avoided. In some cases old routines may even be entirely abolished. One example is the application in the eye of silver nitrate in the prophylaxis of neonatal ophthalmia. Both paracetamol (acetaminophen) and opiates may be useful as analgesics in the newborn. The deficient neonatal glucuronidation of paracetamol is no problem and is compensated by efficient sulphate conjugation. The reluctance to use opiates in more severe pain may be questioned, Data on the pharrnacokinetics and effects of opiates in the perinatal age are scarse but can be obtained from studies where these drugs are given as analgesics to the mother during labor. The routine use of opiates such as pethidine (meperidine) for labor pain may give rise to analgesia also in the fetus and newborn. If this represents a risk or a benefit to the child after birth remains to be assessed. Department of Clinical Pharmacology, Karolinska Hospital, S-10401 Stockholm, Sweden

S 11.03 BENEFIT-RISK EVALUATION OF TOCOLYTIC TREATMENT Marc J.N.C. Keirse Surveys among obstetricians in several countries indicate that there is much uncertainty about the effects tocolytic drug treatment for the prevention and treatment of preterm labour. Enthusiasm for tocolytic treatment~ has paled because of improved neonatal care, maternal complications of the drugs, and realization that their widespread use has not reduced the overall incidence of preterm birth. Yet, prevention of preterm birth as leading cause of perinatal mortality, morbidity, and long-term handicap, remains a high priority. Uncertainty about the effects of tocolysis relates to the nature of preterm labour and of preterm birth, to confusion between substantive and surrogate outcomes of treatment, and to the paucity of adequately controlled data to judge these effects. Successful inhibition of labour depends on early diagnosis, but early diagnosis is so inaccurate as to lead to success rates that are unrealistically high. Many agents have never been evaluated in any other manner. Those that have been evaluated have been assessed more in terms of arrest of contractions and delay of delivery than in terms of whether mother and baby are any better with than without the treatment. To address these uncertainties formal overviews (meta-analyses) were conducted of all controlled trials of any agent used to either prevent or inhibit preterm labour. Agents on which evidence was sought have included progestational agents, magnesium sulphate, relaxin, ethanol, betamimetic agents, prostaglandin synthesis inhibitors, calcium antagonists, erythromycin, diazoxide and oxytocin analogues. Only 3 categories of agents have been evaluated to any significant extent for tocolysis in active preterm labour: ethanol, betamimetics and prostaglandin synthesis inhibitors. The data on ethanol derived from 2 placebo-controlled trials, 5 randomized comparisons with betamimetic agents, and other studies indicate that ethanol should be entirely abandoned for preterm labour. Only 3 of the many betamimetic agents have been evaluated against placebo or no treatment (ritodrine, terbutaline and isoxsuprine). Results from these studies (n=12) indicate that betamimetics can arrest labour, delay delivery, prolong gestation, and reduce the incidence of preterm birth. These effects have so far not been matched by a statistically significant decrease in mortality or severe morbidity of the infant. Trials on the prophylactic administration outside active labour have shown no influence on the incidence of preterm birth, although maintenance treatment (after acute preterm labour) appears to reduce the incidence of recurrence of preterm labour. Few controlled evaluations of prostaglandin synthesis inhibitors have been conducted; all dealt with indomethacin and none were truly placebo-controlled. The data indicate arrest of contractions, delay of delivery, and a reduced frequency of preterm birth and low birthweight. No benefits were detected in infant mortality or morbidity. Wide differences among agents that inhibit prostaglandin synthesis do not justify extrapolation of effects from one agent to another. Departments of Obstetrics of the Universities of Leiden, The Netherlands, and Leuven, Belgium. PO Box 9600, 2300 RC Leiden, The Netherlands.

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S 1,2.02

PHARMACOLOGIC STRATEGIES FOR THE TREATMENT OF ALCOHOL ABUSE AND DEPENDENCE E.M. Sellers The development of new pharmacologic treatments depends on our understanding of the neurobiologic regulation of ethanol intake. The acquisition, maintenance and cessation of alcohol drinking are regulated in different ways. Currently, attention has focussed on the roles of serotonin and dopamine. Drugs could decrease alcohol consumption by modifying the positive or negative reinforcing actions of ethanol; produce a direct or conditioned aversive reaction; decrease the desire to drink; modify mood states or fuctuation that led to drinking; suppress target symptoms, e.g. anxiety, depression, that may prompt or sustain drinking; enhance the learning of behavioural self-management techniques; produce side effects which make drinking less attractive, e.g. nausea, Clinical features of alcohol abuse and dependence suggest a variety of drug strategies are needed or may be effective. Screening of compounds for effects on alcohol consumption is uncommon. A sensitive (< 0.1 ml) high resolution (< t rain) real time confnuous volumetric monitoring system offers new possibilities for pre-clinical detection of effects on micro4:lrinking patterns and importantly in low dependence drinking. Drug effects with serotonin uptake inhibitors can be demonstrated at doses 20- to 50-fold lower than before. At low doses these drugs decrease bout initiation and bout number, but not the size of ethanol drinking bout. GR38032F, a 5-HT 3 antagonist, decreases alcohol consumption in rats at doses of only 0.01-O.1 ~g/kg in this system. Important evolving clinical methodologic issues include: specification of outcome with respect to alcohol (e.g. reduction to safe levels or abstinence) or other measures (e.g. psychosocial consequences); accurate identification of the treatment population; valid and reliable measurement of alcohol consumption; pharmacokinetic appropriateness; incorporation of compliance measures; stratification with respect to severity of problem; characterization of mood states; lifetime and current mental disorders; concurrent other drug use; specification and control of the form and extent of concurrent non.rug therapy; and duration of drug therapy. Regulatory guidelines in this area could help_ Separation among drug treatments for acute detoxication (withdrawal); initiation of reduced alcohol use and maintenance of a lowered alcohol use is of conceptual, strategic and practical importance. Acute withdrawal is readily treated by diazepam loading or equivalent. With respect to initiation of a decrease in use, serotonin uptake inhibitors consistently decrease alcohol consumption and preference in rat drinking models, e.g. citalopram, viqualine, zimelidine, fluvoxamine, sertraline, indalpine and fluoxetine. Four separate randomized double-blind clinical trials (3 cross-over, 1 parallel design) of treatment initiation in heavy social drinkers not seeking treatment (average daily ethanol consumption 95 g) have reported decreases in drinking (mean %): zimelidine 200 mg 9.3% (p < 0.05); citalopram 40 mg 9.1% (p < 0.05); viqualine 200 mg 17.1% (p < 0.05) and fluoxetine 60 mg 16.6% (p < 0.01) with 2 4 weeks of drug treatment. On average the magnitude of response is relatively modest, but the drugs were not given in conjunction with other psychosocial interventions which could maximize the effect. These drugs also decrease body weight (range 0.8 to 2.2 kg over 4 weeks) but do not affect smoking. There are several problems with the agents currently used to maintain nonproblem levels of alcohol intake (e.g. disulfiram). For example, the long-term effects of disulfiram are small, appropriate only to an abstinence goal, and are based on non-pharmacologic actions (vis. expectancy). Lithium significantly reduces relapse among depressed alcoholics; can decrease the need for hospitalization and among compliant non-depressed male alcoholics with serum lithium (> 0.4 mEq/I) significantly improved abstinence at one year (67% vs 44%). No drug has been shown to importantly maintain non-problematic levels of alcohol use on a pharmacologic basis for long periods of time. A variety of other CNS active compounds are active in animal models of ethanol drinking or in decreasing appetitive behaviours, e.g. angiotensin converting enzyme inhibitors; benzodiazepine inverse agonists; calcium channel antagonists; 5-HT1A agonists; opiate antagonists; monoamine oxidase inhibitors; 5-HT$ antagonists; eholecystokinin; and dopamine antagonists. All are potential leads for clinical studies. The high relapse rate of alcohol dependence disorders suggest that initiation of a treatment response (a decrease of alcohol use) and its maintenance are both important. Strategies to achieve a sustained drug effect will likely require combination with behavioural self-management techniques, e.g. selfmonitoring; goal selection; functional analysis of drinking; cognitive restructuring; development of coping strategies. Combining innovative pharmacological and behavioural interventions show considerable promise in the initiation and Iong-terrn treatment of alcohol abuse and dependence. Clinical Psychopharmacology Program, Addiction Research Foundation and Departments of Pharmacology and Medicine, University of Toronto, 33 Russell Street, Toronto, Ontario M5S 2S1, Canada.

TREAT~2~ OF NICOTINE DEPENDENCE M.A.H.Russell Smoking is a drug-taking activity. Most smokers absorb sufficient nicotine to obtain pharmacological effects and to develop dependence. Nicotine can act as a primary reinforcer in animals. It influences mood and performance in humans, induces tolerance, and physical as well as psychological changes occur on withdrawal. Chronic exposure to nicotine induces an increase in the number of nicotinic cholinergic receptors in many parts of the brain indicating the presence of structural as well as function -al changes in the central nervous system which may play some part in the difficulties of giving up smoking. One way to ease these difficulties is to provide nicotine from an alternative and less harmful source. Nicotine polacrilex gum used as an aid to smoking cessation has been shown to alleviate withdrawal symptoms and approximately double the success rates achieved by placebo gum or behavioural methods alone. Its limitations and the potential of other forms of nicotine replacement will be discussed, including a nicotine nasal spray, nicotine skin patches and a cigares plastic device which delivers smoke-free nicotine vapour. The rationale and potential of other pharmacological aids such as clonidine, naltre• and nicotinic blockade with mecamylamine will be briefly discussed.

S 12.03 TREATMENT OF OPIOID DEPENDENCE C.P. O'Brien Pharmacological strategies are useful at each phase of treatment; diagnosis, detoxification, maintenance and relapse-prevention. Diagnosis of physical dependence can be assisted by the use of the short acting opioid antagonist, naIoxone. For detoxifieation, a long acting agonist such as methadone can be used in gradually decreasing dose to ease the symptoms of withdrawal. An alternative is clonidine, a centrally acting alpha 2nonadrenergie agonist which decreases presynaptic noradrenalln. Clonidine diminishes the autonomic aspects of the opioid withdrawal syndrome although some discomfort remains. Repeated failures at remain;ng abstinent can justify the use of methadone as a maintenance treatment. The patient's craving for opioids is relieved and the methadone produces cross tolerance to other opioids thus diminishing their ability to produce pleasure. Methadone has been successful with large popu]ations in the US. The specific opioid antagonist, naltrexone, can be used to prevent relapse in drug-free former opioid addicts. Naltrexone is active at opiate receptors as a competitive inhibitor for up to three days. Abstinent patients who receive naltrexone are thus prevented from impulsively resuming opioid use. In practice, antagonist treatment works best with well-motivated intelligent patients. The partial agonist-antagonlst burprenorphine holds promise because its agonist properties make it more rewarding than naltrexone, and thus more popular with prospective patients. U of Pennsylvania/VA Med Ctr, 3910 Chestnut St./6178 Philadelphia, PA 19104 USA

A 20

S 13.01 SELECTIVITY

OF CALCIUM-ANTAgONISTS

M. Spedding The selectivity their clinical

of calcium-antagonists spectra

the calcium channels sites.

available

may be classed

The calcium-antagonists

dihydropyridines vasodilators; verapamil

into several

for L channels protonateable

and diltiazem

allosterically

for L channels

effects.

As the sodium channel calcium

affinity

class

channel

is inaccessible

selectivity effects

which

resembling

such effects

the

III drugs have equivalent channel

and

in heart and smooth muscle activator

Bay K 8644 Selective

are

indicating

or that they trap

may have clinical

In this respect,

accumulate

during

those of Bay K 8644;

may explain

it in

antagonism

utility

if

acyl carnitines

ischaemia

selective

dependent

Thus,

the clinical

are

and have

antagonism

some of the anti-lschaemic

certain calcium-antagonists. drugs will be highly

homology

oral or interperitoneal treatment with nimodipine in rats bearing a lesion in the sciatic nerve. Age-related deficits in the walking pattern of freely moving rats could be suppressed or delayed by subchronic treatment with nimodipine. In addition, such nimodipine treated rats showed better conduction velocities in the various peripheral nerves tested and a higher fibre density in cross sections of their sciatic nerves. In addition nim~dipine blocks the age-related changes in Ca 2fluxes in rat hippocampal neurons. Besides its antiischemic activity and its beneficial effects on functional deficits that relate to neuronal plasticity, nimodipine was shown to have anticonvulsant activity in mice, rats and rabbits. Nimodipine was considerably more potent than phenytoin in the treatment of electreconvulsive seizures in rabbits. Thus, the therapeutic usefulness of nimodipine in diseases of the nervous system appears not to be limited to cerebral ischemia, but may also include age-related degenerative diseases and epilepsy. Rudolf Magnus Instituut, Vondellaan 6, 3521 GD Utrecht, The Netherlands.

exist and this may allow additional

of antagonists.

lipid metabolites

structural

to Bay K 8644.

activators

activators

which have of clinical

some of these drugs,

either that they do not act on the channel of calcium.channel

etc)

as for the calcium

of these agents

not reversed by the calcium

endogenous

(class III,

and a wide spectrum

between

on the site of action;

a form which

site and which have

prenylamine,

has a strong

for the sodium channel effects

nicardipine, drugs such as

there will be overlap between

for the two channels

inhibitory

are

as

compared with the myocardlum;

fendiline,

withthe depending

(e.g.

cells);

and diphenylbutylpiperidines

channel

which

(cl~ss II) which bind to sites which are

lidoflazine,

little selectivity

affinities

ischaemic

for blood vessels

diphenylalkylamines flunarizine,

dihydropyridines

linked to the dihydropyridine

less selectivity

uncharged

nitrendipine)

but which act predominantly

in acidic,

in

for other

which are currently

groups:

(class I, e.g. nifedipine,

which may accumulate

role in

and will depend on their site of action

(T, N and L) and on affinity

unrelated

very selective

plays a crucial

effects

effects

on their site of action

of of

of these

in the

channel. Syntex Research Scotland,

Centre,

Research

Park,

Riccarton,

Edinburgh,

EHI4 4AP.

S 13.02 CNS-EFFECTS OF NIMODIPINE W.H. Gispen Evidence is accumulating which suggests that Ca ~- entry blockers of the dihydropyridine type have profound neuro- and psychopharmacological effects in animals and man. The mechanism by which such effects are brought about is still u n k n o w n . It may be that the known vascular effects are responsible for the observed neural activity, whereas an alternative mechanism involves the activation of the dihydropyridine receptors present i~ neural tissue. It is evident that neural Ca 2 homeostasis is a key factor in the control of neuronal plasticity. In the developing nervous system it has been shown that a precize regulation of Ca 2 levels plays a key factor in growth cone motility and thus in network formation. Nimodipine was shown to facilitate maturation of primary cultured rat cerebral neurons in vitro. Furthermore, changes in synaptic plasticity as brought about by long-term potentiation in rat hippocampal syn~pses involve Ca 2 entry and activation of Ca2-sensitive processes. Moreover in the aged nervous system, where in general there is a loss of neuronal plasticity, a severe dysregulation o f neural Ca 2 homeostasis exists. In fact, there are indications that age-, lesion-, or disease-related neuronal cell loss in the brain may in part be attributed to a cytotoxic increase in intracellular Ca 2 . It may be that the antiischemic activity of dihydropyridine relates to the amelioration of cytotoxic effects of high calcium levels. Recent studies have suggested that nimodipine may improve learning and memory processes in brain-damaged or old rats and accelerate acquisition of associative learning in aging rabbits. Post-lesion repair was enhanced by

S 13.03 CALCIUM ANTAGONISTS IN MYOCARDIAL ISCHAEMIA AND REPERFUSION Michael J Curtis*, Michael JA Walker, David J Hearse* (i) Introduction- Ca2+ antagonists have negative inotropic and coronary vasodilatory activity, reduce afterload, inhibit vasospasm, and inhibit isi. It is therefore perhaps surprising that in myocardial ischaemia and reperfusion their clinical utility remains controversial (apart from their established value in angina). Consideration of the determinants and consequences of their tissue-selectivity may help to explain this, and furthermore to facilitate development of more disease-specific drugs. (iil Ischaemia-induced arrh7thmias: In animal experiments, in which high doses may be given, Ca2+ antagonists possess antiarrhythmic activity during regional myocardiaI ischaemia. Minimum effective doses of i.v. (+_)-verapamil are -4).79 mg/kg in anaesthetized dogs 1 and --2 mg/kg in conscious rats2. Antiarrhythmic dose-response curves for a series of Ca2+ antagonists have been examined in the conscious rat with regional ischaemia, atSd antiarrhythmic ED50 values have been compared with ventricular isi-blocking EC5o values. The antiarrhythmic potency order ~ was: (-)-verapamil > nifediplne > (+)-verapamil ;, DHM9:~,4. In isolated rat hems, the -lOgl0 EC50 for inhibition of left ventricular developed pressure (an index ofisi-blocking potency) was different: nifedipine > (-)verapamil > (+)-verapamil > DHM9. However, when the concentration + of K in the perfusion fluid was +increased from 3 meq/1 to 10 meq/1 to mimic changes in extracellular K seen in early ischaemia i~;-blockin~ potency order became identical with anlaarrhythmlc potency o r d e r34" ,. Thus, ischaemia-indiiced increases in extracellular K + appear to confer o n Ca2+ antagonists an isi-blocking site-selectivity for the ischaemic versus non-ischaemic ventricle which correlates with antiarrhythmic activity. Low pH (seen in ischaemia) also potentiates Ca2+ antagonist potency in ventricles5. In man. vasodilatation-induced hypotension makes the use of high doses of Ca2+ antagonists unacceptable. However, animal experiments define an antiarrhythmic mechanism which might be harnessed in man if new Ca2+ antagonists were designed specifically for selectivity for ventricular (versus vascular) tissue, and ischaemic versus non-ischaemic tissue. This site-selectivity can theoretically be achieved by targeting for acidic or partially depolarized myocardium. (iii) Reoerfusiorr-induced arrhvthmias: It is possible that repeffusioninduced arrhythmias play a r o l e in sudden death, particularly in association with Prinzmetal's angina. The calcium-dependence of reperfusion-indnced arrhythmias6 suggests the possibility that reduction of calcium entry during reperfusion might be antiarrhythmic. Reperfusion-

A 21

induced arrhythmias in the isolated perfused heart are indeed inhibited by Ca2+ antagonists but the effect appears to be indirect (mediated by bradycardia leading to slowing of rate of development of ischaemic pathophysiology)v rather than direct (via inhibition of ventricular isi). (iv) Infarct size limitation." Intracellular Ca2+ concentrations are known to rise viith prolonged ischaerrda, and an involvement of Ca2+ in the infarct process has been proposed8. Infarct size limitation has been reported with Ca2+ antagonists. However, sustained benefit usually requires reperfusion, and generally only occurs in species with well-developed collaterals9. In rats (few collaterals) with 24h permanent occlusion, pretreated with phenethylalkylamines (verapamil, anipamil and ronipamil) or 1,4-dihydropyridines (nifedipine, felodipine, DHM9) it has not been possible to demonstrate a dose-dependent reduction in infarct sizeTM. Thus, the ability (if any) of C~/z+ antagonists to achieve a lasting reduction in infarct size probably results from indirect actions such as improvement of collateral blood flow. (v) CardioDleeia: In hearts reperfused after surgery, recovery of function is improved-by cold cardioplegic arrest before and during surgery. Clinically, Ca2+ antagonists have been reported to improve outcome in severely ill patients. However, in animal experiments, although Ca2+ antagonists confer additional protection when added to cardioplegic solutions used at nomaothermia, this protection is lost under hypothermic conditionsl0; this indicates that Ca2+ antagonists and cold cardioplegia may share a common mechanism of action. Conclusion: If therapeutic advantage is to be taken of the myocardial protective effects of Caz+ antagonists, particularly their antiarrhythmic actions, drug development needs to focus upon specific targeting for the ischemic myocardium by making use of such properties as vohage- and pH-dependence. 1. Kaumann AJ, Aramendia P. J Pharm Exp Ther 164:326, 1968 2. Curtis M3 et al. Br J Phammc 83:373, ~1984 3. Curtis MJ, Walker MJA. Br J Pharmac 89:137, 1986 4. Curtis MJ, Walker MJA. Br J Pharmac 94:1275, 1988 5. Briscoe MG, Smith HJ. Card Res 16:173, 1982 6. Tosaki A, Hearse DL Am J Physiol 253:1-/225, 1987 7. Tosaki Aet al. JMol Cell Cardiol 19:441, 1987 8. Riemer KA, Jennings RB. Am J Cardio155:107B, 1985 9. Kingroa JG Jr. et al. Circulation 75(Suppl V):V25, 1987 10. Fukunami M, Hearse DJ. Card Res 19:95, 1984 *Ravne Institute. St. Thomas' Hosuital. London. UK. & Dept. Pharmaeol., University of B.C., Vancouver, Canad~

closely with their ability to block Ca 2+ fluxes through L-type Ca 2+ channels in GH 3 pituitary cells. A linear correlation is observed between inhibition of binding and inhibition of flux for ~-8, 8-~, a-~ and 8-B conformational classes of alkaloids, suggesting that they all bind at the benzothiazepine receptor. This has been confirmed by investigating their effects on the kinetics of diltiazem dissociation. These findings demonstrate that molecules which are structurally distinct from diltiazem will bind competitively at the benzothiazepine receptor. Substituted diphenylbutylpiperidines (DPBP's) such as fluspirilene and pimozide also effect Ca 2+ entry blocker bindinE in cardiac membranes, but equilibrium and kinetic studies indicate that these agents do not interact competitively at any of the known sites in the receptor complex. Direct binding studies with [3H]fluspirilene demonstrate that members of this structural class bind with very high affinity to a distinct site which is coupled by unique allosteric interactions to the other receptors in the complex. Given the uniNue effect of metal ions on fluspirilene binding, (channel substrates inhibit, while channel blockers stimulate ligand binding), the site for substituted DPBP's may be located close to the pore structure of the channel. Even though fluspirilene blocks L-type Ca 2+ channel activity in GH 3 cells, it does not display traditional Ca2+ entry blocker pharmacology in cardiac preparations. These results suggest that it is possible to find modulators of L-type Ca 2+ channels which interact at new sites on the channel, and which possess novel pharmacological properties. Department of Membrane Biochemistry and Biophysics, Merck Institute for Therapeutic Research, P.O. Box 2000, Rahway, New Jersey 07065 U.S.A.

S 14.01

S 14.02

DRUG DISCOVERIES THROUGH RECEPTOR STUDIES G.J. Kaczorowski, V.F. King, J.L. Shevell, J.P. Felix, R.S. Slaughter, and M.L. Garcia Ion channels are multiple drug receptors. In many cases high affinity binding sites for agents that modulate channel activity are coupled by either positive or negative heterotropie interactions. By monitoring well characterized ligand binding reactions, it is possible to discover either structurally unique compounds that interact competitively at known sites, or agents that bind at previously uncharacterized drug receptors on channel proteins. Such an approach has been used to identify novel modulators of the L-type Ca 2+ channel in heart. By studying interactions of [3H]nitrendipine, [3H]D-600 and [3H]diltiazem (representing three different structural classes of organic Ca 2+ entry blockers) in purified cardiac sarcolemmal membrane vesicles, it has been shown that each of these compounds binds to.a unique receptor and that these sites are all coupled allosterieally in a receptor complex which is functionally associated with the L-type Ca 2+ channel. A series of bis-benzylisoquinoline alkaloids (benzylisoquinoline dimers linked in a headto-head, tail-to-tail fashion) have been identified for their ability to modulate Ca 2+ entry blocker binding. Tetrandrine, a component of a Chinese medicinal herb used for treating angina, is a member of this structural class. Tetrandrine possesses a diltiazem-like profile as it modulates ligand binding - it stimulates nitrendipine, but inhibits D-600 and diltiazem binding. Equilibrium and kinetic analyses of the three binding reactions demonstrate that tetrandrine interacts competitively at the benzothiazepine receptor. Interestingly, other members of this structural class which differ in their stereochemistry about the chiral isoquinoline carbon modulate nitrendipineVs interaction in a varied fashion - some stimulate, some have no effect, and some inhibit dihydropyridine binding. Yet these agents block diltiaaem binding with a defined rank order of potency'and this relationship correlates

DO R E C E P T O R B I N D I N G A N D F U N C T I O N S T U D I E S PREDICT CLINICAL RESPONSE? D.G. Grahame-Smith R e c e p t o r b i n d i n g a n d f u n c t i o n s t u d i e s can be u s e d in two ways: a) In d r u g d e v e l o p m e n t as a "screen" to p r e d i c t p h a r m a c o l o g i c a l a c t i v i t y and t h e r e f o r e c l i n i c a l effect. b) D u r i n g d r u g t h e r a p y of i n d i v i d u a l p a t i e n t s to p r e d i c t l i k e l y r e s p o n s e or to m o n i t o r the t h e r a p e u t i c a c t i o n of drugs. In d r u g d e v e l o p m e n t the u s e f u l n e s s d e p e n d s u p o n the e x t e n t of k n o w l e d g e a b o u t the c o r r e l a t i o n s b e t w e e n r e c e p t o r b i n d i n g data, their function, pharmacological effect and therapeutic response. Receptor binding d y n a m i c s c a n a l s o be u s e f u l for p r e d i c t i n g c l i n i c a l e f f e c t s : i.e. s p e e d s of a s s o c i a t i o n and dissociation. Examples where receptor studies have helped to p r e d i c t s o m e a s p e c t s of c l i n i c a l u s e f u l n e s s are: B e n z o d i a z e p i n e s , Dopamine a n t a g o n i s t n e u r o l e p t i c s , p e r i p h e r a l MI anticholinergics. However there are serious d r a w b a c k s in p l a c i n g too m u c h r e l i a n c e in d r u g d e v e l o p m e n t on r e c e p t o r s t u d i e s in the p r e s e n t s t a t e of our k n o w l e d g e . T h e y can but f o r m a small but e s s e n t i a l p a r t ~ of the t o t a l i t y of the s t u d i e s needed. During both drug therapy and drug development the u s e f u l n e s s of r e c e p t o r s t u d i e s d e p e n d s on t h e n a t u r e of the r e c e p t o r b i n d i n g of the drug, the t y p e of p h a r m a c o l o g i c a l r e s p o n s e a n d the links b e t w e e n t h a t a n d the therapeutic response. I. B i n d i n g a n d e f f e c t : " O N - O F F " . R e c e p t o r binding studies with Propranolol predict the acute b l o c k a d e of e x e r c i s e and i s o p r e n a l i n e - i n d u c e d t a c h y c a r d i a ' a n d its t r a n s i e n t nature. O t h e r a c u t e g o o d c o r r e l a t i o n s c o u l d be p r e d i c t e d for

A 22 Cont. S 24.02 anticholinesterases in m y a s t h e n i a g~avis, n a l o x o n e a n t a g o n i s m of m o r p h i n e i n t o x i c a t i o n , a n d f l u m a z e n i l r e v e r s a l of b e n z o d i a z e p i n e coma. 2. D r u ~ R e c e p t o r i n t e r a c t i o n n o t e a s i l y r e v e r s i b l e . T h e b i n d i n g of d i g o x i n , s e v e r a l of the o l d e r M A O i n h i b i t o r s , a n d a s p i r i n (for p l a t e l e t s ) to t h e i r r e c e p t o r s is n o t r a p i d l y r e v e r s i b l e . T h i s leads to r e l a t i v e l y l o n g d u r a t i o n s of a c t i o n a n d s i t u a t i o n s w h e r e p l a s m a d r u g c o n c e n t r a t i o n s do n o t s h o w a g o o d correlation with therapeutic response. Such a c o r r e l a t i o n c a n be r e v e a l e d by r e c e p t o r b i n d i n g a n d f u n c t i o n studies. 3. D r u q - r e c e p t o r c o m p l e x r e v e r s i b l e b u t e f f e c t p r o l o n q e d . E x a m p l e s of t h i s are c o r t i c o s t e r i o d therapy and immunisation. Snap-shot receptor binding and function studies will not predict t h e r a p e u t i c r e s p o n s e in s u c h c a s e s as the c a s c a d e of e v e n t s is too complex. 4. A d a p t i v e R e s p o n s e s A d a p t i v e r e s p o n s e s o c c u r in r e s p o n s e to repeated drug administration. T h e s e m a y lead to i n e f f i c a c y of t h e r a p y , d r u g t o l e r a n c e , or on o c c a s i o n s to t h e t h e r a p e u t i c e f f e c t Adaptive r e s p o n s e s to D i g o x i n , A n t i d e p r e s s a n t s , and Neuroleptics are examples. 5. R e c e p t o r s t u d i e s as a q u i d e to t h e r a p y . R e c e p t o r s t u d i e s c a n a l s o be u s e d as a g u i d e to t r e a t m e n t as in the t r e a t m e n t of c a r c i n o m a of the b r e a s t w i t h a n t i - o e s t r o g e n t h e r a p y . M R C C l i n i c a l P h a r m a c o l o g y Unit, U n i v e r s i t y D e p a r t m e n t of C l i n i c a l P h a r m a c o l o g y , R a d c l i f f e I n f i r m a r y , W o o d s t o c k Road, Oxford, OX2 6HE, UK.

w h i c h is o f t e n a c c o m p a n i e d by an i n c r e a s e in r e c e p t o r number. One e x a m p l e of s u c h a B - a d r e n o c e p t o r r e g u l a t i o n is the e f f e c t of c h r o n i c a d m i n i s t r a t i o n of B - a d r e n o c e p t o r a n t a g o n i s t s . L o n g - t e r m t r e a t m e n t of p a t i e n t s w i t h d i f f e r e n t B - a d r e n o c e p t o r a n t a g o n i s t s leads to an i n c r e a s e in cardiac, v a s c u l a r a n d l y m p h o c y t e B - a d r e n o c e p t o r number, but in a s u b t y p e - s e l e c t i v e fashion: n o n - s e l e c t i v e B - a d r e n o c e p t o r anta g o n i s t s like p r o p r a n o l o l or s o t a l o l i n c r e a s e b o t h c a r d i a c B I - as w e l l as c a r d i a c , v a s c u l a r and lymphocyte S2-adrenoceptors , while B 1 s e l e c t i v e a n t a g o n i s t s like m e t o p r o l o l , a t e n o l o l or b i s o p r o l o l i n c r e a s e o n l y c a r d i a c ~ 1 - a d r e n o c e p t o r s but do not a f f e c t c a r d i a c , v a s c u l a r or lymphocyte S2-adrenoceptors. Again, such c h a n g e s in B - a d r e n o c e p t o r n u m b e r are a c c o m p a n i e d by s i m i l a r c h a n g e s in ~ - a d r e n o c e p t o r responsiveness. Finally, not o n l y d r u g s a c t i n g at B - a d r e n o c e p t o r s but a l s o h o r m o n e s can m o d i f y r e c e p t o r n u m b e r and r e s p o n s i v e n e s s . One t y p i c a l e x a m p l e is the e f f e c t of g l u c o c o r t i c o i d s on Ba d r e n o c e p t o r f u n c t i o n : t h e y can i m p r o v e c o u p l i n g of the r e c e p t o r to the a d e n y l a t e c y c l a s e / c y c l i c AMP s y s t e m thus e n h a n c i n g responsiveness without affecting adrenoceptor number. In a d d i t i o n , t h e y are c a p a b l e of rapidly restoring a decreased receptor density, w h i c h m a y be one of the r e a s o n s for t h e i r c l i n i c a l e f f i c a c y in t r e a t m e n t of asthma.

S 14.03

S 15.01

FACTORS MODIFYING RECEPTOR BINDING AND RESPONSE O.-E. B r o d d e R a d i o l i g a n d b i n d i n g s t u d i e s h a v e g r e a t l y adv a n c e d our k n o w l e d g e on the p h a r m a c o l o g y of - and S - a d r e n o c e p t o r s . W i t h t h i s t e c h n i q u e it was for the first time p o s s i b l e to d e t e r m i n e q u a n t i t a t i v e l y the c o n c e n t r a t i o n of ~ - a n d ~a d r e n o c e p t o r s and, hence, the t i s s u e r e s p o n s i v e n e s s to a d r e n e r g i c s t i m u l a t i o n . It r a p i d l y b e c a m e a p p a r e n t that 5 - a n d S - a d r e n o c e p t o r s r a t h e r than b e i n g s t a t i c e n t i t i e s are d y n a m i c a l l y r e g u l a t e d by a w i d e v a r i e t y of drugs, hormones, pharmacologica ! and physiological c o n d i t i o n s . One i m p o r t a n t e x a m p l e of a c l i n i c a l l y r e l e v a n t c o n s e q u e n c e of r e c e p t o r r e g u l a t i o n is the p h e n o m e n o n of " d e s e n s i t i z a t i o n " , i.e. the fact that f o l l o w i n g l o n g - t i m e e x p o s u r e of ~ - a n d B - a d r e n o c e p t e r s to a g o n i s t s the c e l l u l a r r e s p o n s e is b l u n t e d . In a v a r i e t y of t i s s u e s it has b e e n s h o w n t h a t this a t t e n u a t e d r e s p o n s e is due to a d e c r e a s e in r e c e p t o r number. Such d e s e n s i t i z a t i o n p h e n o m e n a a l s o o c c u r in d i f f e r e n t kinds of d i s e a s e s . For example, in c h r o n i c h e a r t f a i l u r e c a r d i a c ~a d r e n o c e p t o r s are c h r o n i c a l l y e x p o s e d to h i g h c o n c e n t r a t i o n s of e n d o g e n o u s c a t e c h o l a m i n e 8 due to an ( c o m p e n s a t o r y ) i n c r e a s e in the s y m p a t h e t i c a c t i v i t y . AS a c o n s e q u e n c e t h e y m a y be d e s e n s i t i z e d . In fact, s e v e r a l g r o u p s h a v e shown that in p a t i e n t s w i t h c h r o n i c h e a r t f a i l u r e c a r d i a c B - a d r e n o c e p t o r n u m b e r is dec r e a s e d and the m a g n i t u d e of this d e c r e a s e is s t r o n g l y r e l a t e d to the d e g r e e of h e a r t failure. C o n c o m i t a n t l y w i t h the d e c r e a s e in r e c e p t o r n u m b e r c o n t r a c t i l e r e s p o n s e s to 6a d r e n o c e p t o r a g o n i s t s are reduced.

RECEPTOR MEDIATED DRUG INTERNALIZATION

C o n v e r s e l y to d e s e n s i t i z a t i o n , a reduced e x p o s u r e of O~- or B - a d r e n o c e p t o r s to a g o n i s t s leads to the p h e n o m e n o n of " h y p e r s e n s i t i v i t y " ,

Biochem. F o r s c h u n g s l a b o r , Med. K l i n i k and P o l i k l i n i k , U n i v e r s i t y Of Essen, D - 4 3 0 0 Essen, Fed. Rep. G e r m a n y .

Andr~ TROUET : MEDGENIX, Brussels and University Cstholique de Louvain, BELGIUM Receptor specific ligands are increasingly studied as carriers for a more selective drug delivery. The practical design of such receptor mediated delivery systems requires a clear understanding and integration of the various cell biological aspects of receptor localisation, metabolism and turnover. Three modalities of receptor mediated drug internalization will be discussed as well as some applications. 1~ Cytoplasmic receptor mediated drug internalization. Ligands of cytoplasmic receptors such as steroid receptors have already been tested as drug carriers. In this case, the drug itself should be able to cross the cell membrane and two different delivery systems should be considered depending on the nature of the drug to carrier linkage. In the first one, the pharmacological activity of the drug is maintained as a carrier conjugate and the selectivity obtained will not depend on an activation process in the target cell but upon an intracellular concentration gradient, function of the affinity of the ligand for its receptor. In the second case, the drug is inactivated by its linkage and it requires to be activated inside the cytoplasm of the target cell after interaction of the carrier with its receptor. 2 ~ Cell surface receptors mediated drug internalization. The ligand carrier is in this case unable to cross cell membranes and two different areas of intracellular drug action have to be considered : exoplasmic space : this space includes -

A 23

S 15.03 mainly the lysosomes, endosomes and other compartment in indirect contact with the extraeellnlar medium. The drugs do not need to permeate through cell membranes and their intracellular activity does not need to be dependent on a reversal of their linking to the carrier. Possible examples are intralysosomal delivery of anti infectious agents or of enzymes. -Cytoplasmic and nuclear spaces Here the drugs have to permeate through cell membranes and their activity rely on a release of the drug from its llgand. These modes of receptor mediated drug internalization will be illustrated by the targeting and negative targeting of antimalarial and anticancer drugs through linking to lactosaminated albumin interacting specifically with hepatocytic receptors.

S 15.02 J. N. Weinstein Abstract not received by April 30, 1989

TRANSEPITHELIAL AND TRANSENDOTHELiAL PASSAGE OF PROTEIN DRUGS E. Tomlinson Proteins have immense structural variety and variability, hence their consideration and use as therapeutic agents. A host of new peptide and protein drugs are expected to be used. clinically in the coming decades. Polypeptides and proteins proposed for therapy usually have regulatory or homeostatis functions. They include both endogeneous polypeptides and proteins and their (heterologous) derivatives. This latter class of molecules may be produced by, inter alia, site-directed mutagenesis, proteolysis, ligated gene fusion, protein aggregation and/ or conjugation with (other) biologically active effector functions. For a few proteins there is little relation between applied dose and effect, but for most it is highly critical, particularly as non-linear doseeffect relationships are often found, (e.g. with parathyroid hormone, substance P and &-sleep inducing peptide). The administration pattern of a therapeutic polypeptide or protein is often a strong determinant of its resultant pharmacokinetic and pharmaeodynamic behaviour. Endocrine-like or autocfine/paracrine-like peptidergic mediators have very different pharmacodynamic and pharmacokinetic properties than low molecular weight drugs, with each type requiring completely different approaches in their clinical application. This is largely due to their varying ability to move through epi- and/or endothelial barriers, their chemical and/or metabolic instabilities in the central and extravascular compartments, and their chronopharmacological properties. The experimental and clinical literature gives that many putative therapeutic polypeptides and proteins are administered in ways which either do not mimic physiologic delivery patterns, and/or are inappropriate for the biological process(es)which they are intended to modify. Selective drug delivery and targeting seeks to achieve the optimal arrival of drug at its site of action in a manner that is appropriate for the disease and the drug, and which leads to a significant reduction in the possibility for drug side effects. Advances in molecular and cell biology are enabling the production of hybrid fusion protein drugs, and the definition and exploitation of lhe transport routes used by both normal exogeneous materials (e.g. vitamins) and pathogens (e.g. viruses) Transendothelial movement of macromolecular proteins may be through a passive and/or an active mechanism, both of which are often altered by the presence of disease. For example, the size selectivity for the passive extravasation of macromolecules through normal continuous endothelium is for an Einstein-Stokes radius of 8rim, which rises t O perhaps 1000 nm when extravascular inflammation occurs. Transepithelial transport of proteins may also be via a passive and/or an active mechanism. Passive transport occurs to a significant degree in neonates. Evidence for adults is that this occurs to a very small extent. Some proteins and enzymes have been reported to be absorbed through the intestinal tract membrane of numerous species, including chymotrypsin, insulin, horseradish peroxidase, pancreatic lipase, and Serratia protease, etc.; immunoglobulins, intrinsic factor and various hormones are known to be absorbed via a receptormediated endocytosis process allowing specific and rapid uptake of a significant fraction of applied dose. Some groups are attempting to utilise natural transport processes for the effective transepithelial passage of polypeptides and proteins (e.g. the cobalamin/intrinsic factor complex). Although only small, the amounts of protein that can traverse the tract membrane are often described as being significant in terms of pharmacological response. For example, the oral administration of urokinase in adult humans induces a plasma flbrinolytic staging, suggesting the transport of urokinase across the intestinal tract membrane in amounts sufficient to at least stimulate the synthesis and/or release of endogeneous urokinase-type proteins. The process of epithelial transport is often saturable, (as described for numerous proteins including Serratia protease, serum albumin, lipase and [odinated elastase). This present contribution examines how the control of the biological disposition of proteins may be achieved using both protein remodelling and synthetic adduction as well as by various modes of administration. Advanced Drug Delivery Research, Ciba-Geigy Pharmaceuticals, Horsham. West Sussex, RH14 OUT, United Kingdom

A 24

S 16.01 CANCER CHEMOTHERAPY: DOSE INTENSITY AND DOSE RESPONSE W.M. Hryniuk In humans, attempts to define optimum treatment have resulted in many schedules and combinations, and many schemes to reduce doses and delay treatments. However, these schemes and schedules have obscured dose-response relationships. Dose-response relationships can be rediscovered and studied by reducing all to how much drug is given per unit time, as mg/M2/wk. This is dose intensity. Dose intensity may be calculated from intended drug doses ("projected dose intensity") or from dose received after reductions and delays for toxicity ("received dose intensity"). To calculate received dose intensity, treatment delays, and dose reductions and are accorded equal weight arithmetically. For regimens containing only one drug, dose intensity may be calculated simply by disregarding the protocol schedule and expressing the treatment in the standard form: mg/M2/wk. For regimens containing more than one drug, dose intensity can be calculated by arbitrarily choosing one regimen as the standard and expressing all other regimens relative to the standard. Dose intensity Correlates very well with outcome of single and combination agent regimens in various malignant diseases. In animal model systems, dose intensity and total dose (dose intensity x duration of treatment) are independent determinants of antitumor effect. There are insufficient data from human studies to allow the same deduction to be made. Ontario Cancer Foundation, Hamilton Regional Cancer Centre and McMaster University, 711 Concession Street, Hamilton, Ontario, Canada LSV IC3

tumor cells prior to exerting their biological activity. Despite these limitations, there ere areas where TDM could prove of benefit in cancer chemotherapy. Recent studies of oral 6-mercaptopurine (6-MP) in maintenance therapy of ALL of childhood using specific assays have shown that the bioavailability is only 10-20% with large inter- and intraindividual variations. This treatment is usually given for 2-3 years. Yet about I/3 of patients in complete remission relapse. We have repeatedly (median 7 times) determined plasma concentrations of 6-MP in 22 consecutive childran with ALL. 5 patients with low plasma concentrations relapsed. 4 children with much higher concentrations developed severe myelotoxicity necessitating a temporary cessation of the therapy. The results indicate that the plasma concentrations of 6-MP are of significance for the outcome of the treatment although the drug is to be considered a prodrug since 6-MP like nk~ny other antimetabolites is extensively metabolized intracellularly to nucleotide triphosphates which are believed to exert the cytotoxicity. This problem is illustrated by the lack of correlation between the ara-C level in plasma and the ara-CTP-level in leukemic cells isolated from patients receiving high-dose ara-C as single drug therapy. Intracellular ara-CTP but not plasma ara-C correlated to t h e remission rate in relapsed acute leukemia patients. In spite of the growing awareness of the pronounced interindividual variability in the pharmacokinetics of antineoplastic drugs, cancer chemotherapy is most often given in standardized regimens. There are situations where the therapy can be individualized based on drug determinations in plasma or target cells or tissues. Department of Clinical Pharmacology, Karolinska Hospital, RO Box 60500, S-I04 01 Stockholm, Sweden.

S 16.02

S 16.03

CAN D R U G C O N ~ T I O N MONITORING IN ONCOLOGY IMPROVE THERAPY? C. Peterson, J. Liliemark, and P. Lafolie Progress in drug assay methodology during recent years has led to increased knowledge of the pharmacokinetics of antineoplastic drugs. Fof many other drugs, it has bean shown that the plasma concentration provides a better correlation with effect than does the dose. However, the routine use of therapeutic drug monitoring (TDM) in ontology is at present limited to measurement of plasma methotrexate after high-dose therapy where a correlation to toxicity but not to antineoplastic effect has been shown. Plasma concentration monitoring is also used for pharmacokinetically guided dose escalation in phase I trials based on the assumption of a correlation between plasma concentration and toxicity. A typical empirical approach in cancer chemotherapy is to deliver the standard dose of drug or drugs to the patient and then adjust doses on the next cycle, based on clinical observations of toxicity. However, data are accumulating for a dose-response relationship for anticancer drugs not only in predictive test systems in clonogenic cells but also in clinical trials where the dose intensity has been found to correlate to remission rates and patient survival. There are certain factors that make a correlation between plasma concantration and response to anticancer agants mere likely than between dose and response. Pronounced interindividusl variation in the pharmacokinetics has been found for many antineoplastic drugs. Certain drugs show dose-dependent pharmacokinetics. Cancer patients often exhibit changes in drug disposition due to disturbances in liver or renal functions. Other factors make the value of TOM in oncology questionable. Thus certain anticancer drugs exert irreversible binding to DNA and under such circu/r~tances, the time course of effects can hardly be reflected by the ti/ne course of drug concentration in plasma. There are several other problems. Drugs are often used in combination in intermittant courses (eg once every 3-4 weeks), the tumor cell populations are heteroganous, and antimetabolites need to be biotransformed within the

M E C H A N I S M S OF M U L T I D R U G R E S I S T A N C E AND I M P L I C A T I O N S FOR T H E R A P Y T a k a s h i Tsuruo One of the m a j o r p r o b l e m s in c a n c e r c h e m o t h e r a p y is the d e v e l o p m e n t of d r u g r e s i s t a n c e during treatment. The n a t u r e of drug r e s i s t a n c e in cancer patinets is c o m p l e x . One r e a s o n for the c l i n i c a l r e s i s t a n c e is the m e t a b o l i c inactivation, or e x c r e t i o n of a n t i t u m o r a g e n t s by the liver, k i d n e y and other o r g a n s . In addition, it has b e e n f o u n d that t u m o r c e l l s can a c q u i r e r e s i s t a n c e to a n t i c a n c e r drugs. It is g e n e r a l l y a c c e p t e d now that drug r e s i s t a n c e at the c e l l u l a r level ( c e l l u l a r r e s i s t a n c e ) is also an i m p o r t a n t m e c h a n i s m of drug r e s i s t a n c e in patients. T h e r e are two t y p e s of c e l l u l a r r e s i s t a n c e . One is the i n n a t e (natural, de novo) r e s i s t a n c e , and the o t h e r is the a c q u i r e d r e s i s t a n c e to a n t i t u m o r agents. Colon cancer, renal cancer, g a s t r i c cancer and o t h e r solid t u m o r s are known to r e s p o n d only m a r g i n a l l y to a n t i t u m o r agents. This type of c e l l u l a r r e s i s t a n c e is c l a s s i f e d as i n n a t e (natural) drug r e s i s t a n c e . D u r i n g the t r e a t m e n t of t u m o r s w i t h a n t i t u m o r agents, tumor c e l l s can a c q u i r e r e s i s t a n c e to the drugs. This type of r e s i s t a n c e is c l a s s i f i e d as a c q u i r e d drug r e s i s tance. Innate and a c q u i r e d drug r e s i s t a n c e s are major f a c t o r s l i m i t i n g the c l i n i c a l use of ant i t u m o r agents. When tumor c e l l s a c q u i r e r e s i s t a n c e to n a t u r a l l y occurring antitumor agents such as vinca a l k a l o i d s or a n t h r a c y c l i n e s , they g e n e r a l l y show cross r e s i s t a n c e to other a n t i t u m o r a g e n t s h a v i n g d i f f e r e n t s t r u c t u r e s and d i f f e r e n t m o d e s of action. T h i s type of r e s i s t a n c e has been w i d e l y and g e n e r a l l y o b s e r v e d in v a r i o u s e x p e r i m e n t a l t u m o r s , and is c a l l e d " m u l t i d r a g resistance." R e c e n t p r o g r e s s in b i o c h e m i c a l s t u d i e s of m u l t i drug r e s i s t a n c e has r e v e a l e d a g l y c o p r o t e i n as a k e y m o l e c u l e in the m e c h a n i s m s of r e s i s t n a c e .

A 25

S 17.02 This glycoprotein, termed P-glycoprotein, is ass u m e d to be a p u m p i n g molecule of v a r i o u s antitumor agents outside tumor cells. As t h i s protein possesses a key function in m u l t i d r u g r e s i s t a n t tumor cells, t h e r a p e u t i c a p p r o a c h targeting P-glycoprotein would p r o v i d e a lot of int e r e s t and a d v a n t a g e s in t r e a t m e n t of m u l t i d r u g resistance. We f o u n d that P - g l y e o p r o t e i n is a k i n d Of A T P a s e . The inhibitors of the A T P a s e activity of Pglycoprotein can theoretically overcome the resistance. Calcium channel blockers, which were f o u n d in 1981 to be e f f e c t i v e in r e v e r s i n g the drug r e s i s t a n c e , now are p r o v e n to be r e a c t i v e to P - g l y c o p r o t e i a . The a g e n t s , s i m i l a r to calc i u m c h a n n e l b l o c k e r s , w h i c h can i n t e r a c t w i t h Pg l y c o p r o t e i n can a l s o t h e o r e t i c a l l y o v e r c o m e the multidrug resistance. I w i l l d i s c u s s our r e c e n t p r o g r e s s on the d e v e l o p m e n t of n e w a g e n t s e f f e c tive for o v e r c o m i n g of drug r e s i s t a n c e . Finally, monoclonal antibodies raised against Pg l y c o p r o t e i n w o u l d also be e f f e c t i v e for t h e r a p y of drug r e s i s t a n c e as wel.l as for the d i a g n o s i s of d r u g resistance. We h a v e developed two monoclonal antibodies MRKI6 and MRKI7. These monoclonal antibodies can potentiate antitumor effect of the d r u g s a n d a l s o can i n h i b i t the g r o w t h of tumor cells. The a n t i b o d i e s a g a i n s t Pg l y c o p r o t e i n s h o w e d t h e r a p e u t i c e f f e c t in m u l t i drug r e s i s t a n t tumor b e a r i n g mice. In a d d i t i o n to P - g l y c o p r o t e i n , multidrug resistant tumor cells also p o s s e s s other m e c h a n i s m s of r e s i s t a n c e , the m a j o r i t y of them still r e m a i n unclear. T h e o r e t i c a l a p p r o a c h e s by t a r g e t i n g t h e s e m e c h a n i s m s of r e s i s t a n c e may e v e n t u a l l y solve the p r o b l e m s of m u l t i d r u g r e s i s t a n c e w h i c h is c r u c i a l in the t r e a t m e n t of c a n c e r p a t i e n t s . Cancer Chemotherapy Center, Japanese Foundation for C a n c e r R e s e a r c h , Kami-lkebukuro, Toshima-kn, T o k y o ]70, Japan.

S 17.01 M. Califf Abstract not received by April 30, 1989.

ALTERNATIVES TO THE RANDOMIZED TRIAL: THE ROLE OF CASE-CONTROL STUDIES IN PHARMACOEPIDEMIOLOGY M.S. Kramer The case-control design is a potent tool for analytic (cause-and-effect) epidemiologie research that is particularly suited for studying rare or delayed outcomes. In pharmacoepidemiology, case-control studies have been used to study both intended (therapeutic) and unintended (adverse) drug effects. When therapeutic benefits are modest, small clinical trials may lead to inconclusive results. In these cases, case-control studies have been used to improve statistical efficiency. The validity of the casecontrol method can be enhanced by adapting methodologic features of the randomized trial: strict inclusion and exclusion criteria, standardized interview or data abstraction procedures to reduce random and systematic measurement error, and definitions of "exposure" that ensure that the drug under study was taken at an appropriate time and in an appropriate dose to produce the intended effect. But the potential for confounding by the clinical indication for drug treatment is far more difficult to control, unless the reason for treatment or nontreatment is straightforward and can be measured with validity and precision. Thus, for investigating intended drug effects of modest magnitude, a large clinical trial, or a meta-analysis of smaller ones, is usually preferable. Many adverse effects, however, are so rare and/or delayed that even large clinical trials cannot detect them. The casecontrol study is then probably the best available epidemiologic tool. Pharmacoepidemiologic studies should strive, whenever possible, to provide information that can influence the decisions made by clinicians, drug regulators, pharmaceutical manufacturers, and public health policy makers. This information should therefore bear on the relative benefits and risks of a given drug with respect to treatment for the same condition in similar groups of patients. Studies should pose three questions concerning these risks and benefits: (i) To whom do they accrue? (2) For what period of time? and (3) Compared with what? First, drug effects risk should be measured in clinically and sociodemographically relevant subgroups of patients with particular clinical indications. Second, these effects should be evaluated as a function of the time since onset of therapy, since effects (particularly adverse effects) may not be the same after six months of chronic therapy as in the first or second week. Many previous case-control studies of adverse effects have failed on this point, since the only timing issue they addressed was the time of exposure to the drug prior to onset of the adverse event, with no consideration of timing with respect to the onset of treatment. Third, as in clinical trials, it is important to compare the benefits and risks of a drug with those of some other real therapeutic option for patients with the same clinical indication. Most case-control studies of adverse effects have considered drug exposure much as cigar/tte smoking, i.e., presence or absence. In determining the adverse effects of cigarette smoking, it may well be appropriate to compare smokers and nonsmokers. But in therapeutic situations involving patients with clinical conditions that require treatment, the appropriate comparison is usually not drug vs no drug, but among alternative treatments for the same condition. This conceptual framework of evaluating drug effects in the context of risks and benefits and available treatment alternatives leads to several suggestions for future case-control studies in pharmacoepidemiology. Consideration of these issues in future case-control studies may help provide information that is of practical use to clinicians, manufacturers, regulators, and the public health community. Department of Epidemiology and Biostatistics, McGill University, 1020 Pine Avenue West, Montr4al, Quebec, Canada H3A IA2

A 26

S 17.03 NON-RANDOMIZED CLINICAL TRIALS IN CANCERCHEMOTHERAPY

debrisoquina autosomal

Edmund A. Gehan

hydroxylation

controlled with

was

recessive heredity.

Neither sex nor

smoking habits affected.

~uan%itative, comparative c l i n i c a l t r i a l s in cancer chemotherapy can sometimes be accomplished without randomizing patients %o a control group. In experimentation other than c l i n i c a l t r i a l s , the advantages of randomization are unquestioned, but ethical issues in c l i n i c a l %rials suggest the p o s s i b i l i t y of using h i s t o r i c a l control groups in certain circumstances. Factors %o consider in planning a comparative c l i n i c a l t r i a l are: the expected difference between treatments, the knowledge of prognostic factorsj the number of pat i e n t s a v a i l a b l e per year and the s t a t i s t i c a l power and significance level of the t r i a l . Advantages of conduc%ing non-randomlzed control studies w i l l be given and %hose features favoring the nonrandomized t r i a l summarized. Arguments for conducting non-randomized %rials in cancer chemotherapy are: the record of accomplishment in the discovery of new therapies, %he f a c t that a l l knowledge is based on historical e v i dence, smaller sample size and shorter length of study, ethical considerations, recruitment of patients, resolution of controversial questions, s i m p l i c i t y of design and execution, and c r e d i b i l i t y through confirmatory studies. Examples will be given of non-randomized %rials leading %o new knowledge in cancer chemotherapy.

The frequency

distribution

of debrisoquine

meta-

bolic ratio in chinese subjects has been shifted to right.

It probably

of the drug oxidative

showed that metabolism

lower than that in Caucasians. of the reasons

of

the

lower

the capacity in Orientals

is

May be it is one

dosage of drugs used

in chinese clinic. Some pharma~okinetic after a single

oral

parameters dose of 10mg

of debrisoquine of debrisoquine

were evaluated in 11 chinese healthy t 89 of debrisoquine

volunteers:

and 4-OH~debrisoquime

were

2.78~0.44 h and 2.73~0.78 h; K were 0.2552~0.041 7 and 0.2783~0.1047 cant

difference

debrisoquine

h -1.

There was no signifi-

in t89 of debrisoquine

between

but a significant

our and Sloan's

variation

and 4-OHresults,

existed in compari-

son with the data from Silas.

University of Texas M.D. Anderson Cancer Cen%er, Department of Biomathematics, 1515 Holcombe Blvd., Hous%on, Texas 77030, U.S.A.

Preparation

of the human

liver microsomes

(chi~

nese) and its activity have been investigated. Department

of Pharmacology

university,

Beijing,

of Beijing

Medical

P.R. of China

S 18.01

S 18.02

DIFFERENCES IN OXIDATIVE DRUG METABOLISM BETWEEN

DIFFERENCES IN DRUG ACETYLATION BETWEEN ORIENTALS AND CAUCASIANS - - IMPLICATIONS FOR THE INCIDENCE OF ADVERSE DRUG REACTIONSAND ASSOCIATED IDIOPATHIC DISEASES T. Ishizaki and Y. Horai During the last two decades, valuable informations have been accumulated on N-acetylation pharmacogenetics and its clinical implications including the relationships between variations in individual metaboli.c capacity of relevant drugs and their toxic effects and the suscept i b i l i t y of d i f f e r e n t phenotypes to certain idiopathic diseases. Acetylatien polymorphism refers to a genetically determined difference in the N-acetylation capacity of many c l i n i c a l l y useful drugs such as isoniazid (INH), procainamide, hydralazine, dapsone (DDS), and sulfasalazine, as well as some putative carcinogenic arylamines (e.g., be,~zidine). Individuals are classified bimodally as either slow (SA) or rapid acetylater (RA): SAs are autosomal homozygous recessive, while RAs are either heterozygous or homozygous dominants. There are pronounced interethnic differences in the frequency distribution of SAs and RAs between Orientals and Caucasians(Table). I t is interesting Frequency of SAs in Orientals and Caucasians Orientals % Caucasians Ainu 13 British 53-62 Japanese 7-12 Canadians 59-70 Korean ii Czechoslovakians 60 Mainland Chinese 13 Finns 61-64 Ryukyuan 15 French 59 Singapore Chinese 22 German 57 Taiwan Chinese 22 Norwegians 56 Thais 18 Swedes 51-68 Thailand Chinese 34 USA Whites 52-57 to see that the incidence of SAs tends to increase among Orientals residing from the northern to southern geographical regions (Table). This tremendous racial d i f f e r ence between Orientals and Caucasians may be c l i n i c a l l y s i g n i f i c a n t in terms of not only therapeutic response to but also incidence o f adverse e f f e c t s of N-acetylateddrugs i f t h e i r dose is prescribed on the basis of the so-called

ORIENRALS AND CAUCASIANS - ARE THEY IMPORTANT FOR THE CLINICAL USE OF THE DRUGS AFFECTED Y.C. LOU Polymorphic

oxidation of debrisoquine,

codein

and mephenytoin has been investigated and two phenotypes o c c u r

in the chinese

population,

extensive and poor metabolizers. lower

frequency

ne hydroxylation methylatien Caucasian

distribution (I%)

population

a much higher

of poor

S/R enantiometric investigation

in chinese

between t h e

ratio and the mephenytein

drug metabolic

catalyzed by different

of poor

volunteers

ratio which confirms

that

separated genetic

there is

of distribution

(14.7%). We found me correlation metabolic

O-de-

with the data from

(5-9~). However,

frequency

mephenytoin hydroxylation debrisoquine

debrisoqui

and of poor codeine

in comparison

i.e.

There is a

enzymes

control.

previous

reactions

are

which are under

The very similar

results have been found in studies

on debriso-

quine and mephenytoin hydroxylation

phenotypes

in Japanese population.

It showed considerable

interethnic

variations

in Orientals and Cauca-

sians. The results

of chinese

family study

quine hydroxylation

supported

on debrise-

the view

that

A 27

"usual" dose concept. However, clinical significance of acetylator phenotype in relation to therapeutic response to acetylated drugs remains obscure and not uniyersally accepted. For instance, on a theoretical ground, RAs with pulmonary tuberculosis who receive a once-a-week, but not twice-a-week or daily regimen, might become therapeutic failures. Although this has been recommended, i t seems unproven whether acetylator phenotype produces a c l i n i c a l l y significant difference in the outcome of currently used INH regimens. In contrast, there has been an evidence indicating that SAs are more prone to develop INH- and hydralazine-induced peripheral neuropathy, procainamide- and hydralazine-induced lupuslike syndrome, occupational arylamine-induced bladder cancer, and sulfasalazine-induced side-effects. However, whether the above-mentionedadverse reactions would less occur in Orientals than in Caucasians remains unknown. Among idiopathic diseases that have been related to E~cetylation pharmacogenetics,systemic lupus erythematosus and non-occupational bladder cancer seem to be the most controversial ones. Although these two disorders have been reported to occur more frequently in Caucasian SAs, we have not observed any predominance of SAs in the Japanese patients with either of the above-mentioned diseases as compared with the respective controls where RAs predominate very much. Finally, i t is unfortunate to state that clinical implications derived frominterethnic differences in N-acetylation pharmacogenetics between Orientals and Caucasians remain very l i t t l e known. In this context, an interglobal pharmacogenetic study would help settle many aspects of the unresolved interethnic differences in clinical pharmacoepidemiology. Clinical Research Institute, National Medical Center, Toyama 1-21-2, Shinjuku-ku, Tokyo 162, Japan

The m e c h a n i s m s of t h e s e i n t e r e t h n i c d i f f e r e n c e s are n o t yet clear, a l t h o u g h it m a y be s p e c u l a t e d t h a t g e n e t i c o r e n v i r o n m e n t a l f a c t o r s are r e s p o n s i b l e for t h i s p h e n o m e n o n . W h i l e the C h i n e s e w h o p a r t i c i p a t e d in t h i s s t u d y h a d b e e n l i v i n g in S w e d e n for some time (a few w e e k s to less t h a n 8 y e a r s ) , a l m o s t all of t h e m ate C h i n e s e f o o d and k e p t C h i n e s e h a b i t s . It is p o s s i b l e t h a t C h i n e s e f o o d lacks c o n s t i t u e n t s w h i c h i n d u c e g l u c u r o n i d a t i o n , or c o n t a i n s s u b s t a n c e s t h a t i n h i b i t the g l u c u r o n i d a t i o n of c o d e i n e . A d d i t i o n a l l y , the e x i s t e n c e of u n k n o w n m e t a b o l i c p a t h w a y s in the C h i n e s e p o p u l a t i o n can not be e x c l u d e d . H o w e v e r , g e n e t i c and environmental (nutritional, dietetic and even climatic) f a c t o r s s h o u l d be i n v e s t i g a t e d systematically. In s u m m a r y , l a r g e i n t e r e t h n i c d i f f e r e n c e s between Caucasians and Chinese have been shown to e x i s t .in the g l u c u r o n i d a t i o n of c o d e i n e . D i f f e r e n c e s in d r u g m e t a b o l i s m m a y lead to d i f f e r e n c e s in s t e a d y - s t a t e c o n c e n t r a t i o n s , a n d h e n c e in the e f f e c t s of drugs. T h e r e f o r e d o s e s of t h o s e d r u g s w h i c h u n d e r g o e x t e n s i v e c o n j u g a t i o n w i t h g l u c u r o n i c a c i d w h i c h are s u i t a b l e for one e t h n i c p o p u l a t i o n m a y not be a p p r o p r i a t e for a n o t h e r p o p u l a t i o n . IDept of C l i n i c a l P h a r m a c o l o g y , H u d d i n g e U n i v e r s i t y H o s p i t a l , S-141 86 H u d d i n g e , S w e d e n ; 2 D e p t of P h a r m a c o l o g y , C h i n a M e d i c a l ' U n i v e r s i t y , Shenyang, China

S 18.03

S 18.04

I N T E R E T H N I C D I F F E R E N C E S IN G L U C U R O N I D A T I O N OF DRUGS - POSSIBLE MECHANISMS AND CLINICAL IMPLICaTiONS, Q. Yue , J.O. S v e n s s o n 9, J. S~we I T h e o c c u r e n c e of i n t e r i n d i v i d u a l a n d i n t e r e t h n i c d i f f e r e n c e s in d r u g m e t a b o l i s m h a s been well d o c u m e n t e d for d r u g s w h i c h are a c e t y l a t e d or o x i d i z e d in a p o l y m o r p h i c f a s h i o n , but m u c h less is k n o w n in t h i s r e g a r d for d r u g s w h i c h are eliminated by glucuronidation. C o n j u g a t i o n w i t h g l u c u r o n i c a c i d is a m a j o r m e t a b o l i c p a t h w a y for m a n y drugs. It is b i o c h e m i c a l l y c o m p l e x a n d t h e r e b y l i k e l y to be s u b j e c t to b i o l o g i c a l v a r i a t i o n due to b o t h g e n e t i c and e n v i r o n m e n t a l factors. M o r e o v e r , the e x i s t e n c e of m u l t i p l e f o r m s of U D P - g l u c u r o n o s y l t r a n s f e r a s e has b e e n s u g g e s t e d . An i d e a l d r u g for s t u d y i n g g l u c u r o n i d a t i o n s h o u l d be m e t a b o l i z e d m a i n l y by this r o u t e a n d be safe e n o u g h to b e g i v e n to a large n u m b e r of v o l u n t e e r s . C o d e i n e f u l f i l l s t h e s e c r i t e r i a and was u s e d in a s t u d y c o m p a r i n g the m e t a b o l i c p a t t e r n b e t w e e n two e t h n i c g r o u p s , C a u c a s i a n s and C h i n e s e . A s i n g l e oral dose of c o d e i n e (25 mg) w a s g i v e n u n d e r s t a n d a r d i z e d c o n d i t i o n s to 149 u n r e l a t e d h e a l t h y C a u c a s i a n s a n d 133 u n r e l a t e d h e a l t h y C h i n e s e l i v i n g temporarily in Sweden. C o d e i n e a n d its m e t a b o l i t e s in 8 - h o u r u r i n e c o l l e c t i o n s w e r e d e t e r m i n e d by HPLC. The results revealed large interethnic differences, in t h a t the t o t a l u r i n a r y r e c o v e r y of C o d e i n e a n d its m e t a b o l i t e s was 74• in C a u c a s i a n s a n d 60• (meaniSD) in C h i n e s e (p< 0.001). C o d e i n e - 6 - g l u c u r o n i d e a c c o u n t e d for 62% of the d o s e in C a u c a s i a n s , c o m p a r e d to 44% in C h i n e s e (p < 0.001). In c o n t r a s t , u n c h a n g e d c o d e i n e was e x c r e t e d to a m u c h l o w e r e x t e n t in C a u c a s i a n s c o m p a r e d to C h i n e s e (4.3% a n d 7.3% of the dose, respectively; p<0.001).

INTERINDIVIDUAL AND INTERETHNIC DIFFERENCES IN THE METABOLIC ACTIVATION OF THE BIGUANIDE ANTIMALARIALS *+S.A. WARD, *+N.A. Helsby, ** W.M. Watkins, *+G. Edwards, *+ R.E. Howalis & *A.M. Breckenridge. Proguanil (PG) is an arylbiguanide which is used extensively as an antimalarial agent. The drug is relatively inactive per se requiring cytochrome-P450 mediated activation to its principal metabolite cycloguanil (CG). large inter-subject variability in circulating CG concentrations have been observed following oral administration of PG to man (Watkins et. al. 1987 J. Pharm. Pharmacol. 39, 261-265). This variability is due to differences in the ability of individuals to convert PG to 03. k~ have shown that the ratio of PG to CG in either a 0-8 hour urine sample or in a spot urine sample taken from individuals at steady state with respect to PG, is a measure of an individual's ability to form CG (Ward et. al. 1989 Br. J. clin. Pharmacol. in press). We have used this PG/CG ratio to investigate interindividual variability in three separate population studies. Population (i) comprised 135 male British Troops on tour duty in Kenya. All subjects were at steady state with respect to PG and provided a spot urine sample approximately 8 hours after a 200rag dose of PO (po.) The frequency distribution profile of urinary PG/CG was non-normal with ratios ranging from 0.5 to 39. However, 90% of the population formed a discrete distribution with PG/CG ratios between 0.5 and 9.0, with the remaining 10% having ratios between 13 and 39. In a second population study (healthy Europeans, n=80, population study (ii) the frequency distribution profile of PG/CG was similar to the profile obtained from population (i), although only 2 (3%) exhibited a ratio ~ I0. The third population, studied (iii) comprised 75 Kenyan subjects. The frequency distribution profile for PG/CG in this group differed from that obtained from the predominantly European populations (i) and (ii). PG/CG ratios ranged from 0.5 to 69 and although the distribution was again skewed, a discrete distribution between 0.5 to I0 was not apparent, although 90% of the population exhibited ratios between 0.5 and 17. If we compare this distribution with the major mode of the distribution observed in populations (i) and (ii) (PG/CG 0.5-10) 26% of the

A 28 Cont. S 18.04 Kenyan population fall outside this mode. We have shown that this data is not subject to intra-individual variation as subjects (n=30) have had PG/CG ratios determined on two separate occasions at least one month apart without any change i n this ratio. The observation that the frequency distribution profiles for PG/CG differ between European and African populations coupled with the fact that all 26 Gurkha troops studied as part of population (i) exhibited ratios between 0.5 and 3 suggests a genetic basis for the observed variability. We have tested the hypothesis that the metabolism of PG may be controlled either by the debrisoquine or the mephenytoin hydroxylase enzymes and therefore cosegregate with one of the known genetic polymorphisms of oxidative drug metabolism. We have shown that mephenytoin but not sparteine can competitively inhibit the formation of CG by human liver microsomes. We w i l l present data which demonstrate the pharmacokinetic consequences of this variability. We suggest that the metabolism of PG to CG is under the control of the mephenytoin hydroxylase enzyme exhibits a genetic polymorphism in the population, explaining the earlier reports of variability in CG concentrations. The observation that the Kenyan population exhibited generally larger PG/CG ratios than the European populations may indicate a greater incidence of the poor metaboliser phenotype in East Africans and highlights the importance of inter-ethnic differences in drug metabolism. As PG is an extensively used pro-drug the consequences of this polymorphism mey play an important role in both the therapeutic failures seen w~th PG and the development of drug resistance by parasites exposed to subcurative CG concentrations in individuals with the deficiency. *+Dept. of Parasitology, Liverpool School of Tropical Medicine, *Dept. of Pharmacology &Therapeutics, University of Liverpool, U.K., **We]Icome Trust Research Labs. Nairobi, Kenya.

the specific mer~rane receptors for LDL are activated in order to accelerate assimilation of the lipoprotein. Conversely, when the intracellular sterol pool is replete, the receptor mechanism is downregulated in order to protect the cell from the toxic effects of cholesterol acctm~ulation. Defective operation of the receptor, the hallmark of familial hypercholesterolasmia, results in severe and premature coronary atherosclerosis. Here t h e burden of cholesterol elimination falls upon less well understood, receptorindependent mechanisms. These apparently lead to accumulation of cholesteryl esters in the scavenger cells of the monocyte-macrophage system.

S 19.01

S 19.02

PATHOPHYSIOLOGY OF HYPERLIPIDAEMIA

A. Chait Abstract not received by April 30, 1989

The hyperlipoproteinaemias are among the most commonly encountered metabolic derangements seen in clinical practice, and are important because of their frequent association with atherosclerot ic vascular disease. Although their underlying biochemical defects are not yet completely elucidated, sufficient comprehension of normal lipoprotein metabolism has now been acquired to permit us to ascribe mechanisms to these clinical conditions as we know them. Each day we ingest about 120 g of dietary fat containing 500 mg of cholesterol. These lipids are transported in the form of triglyceride-rich chylomicron particles to the bloodstream via the thoracic duct. There they are bydrolysed by the enzyme lipoprotein lipase on the luminal surface of adipose tissues and skeletal muscle capillary beds. More than 95% of chylomicron triglyceride is hydrolysed in this way, leaving behind a relatively cholesterol-rich secondary ("remnant" ) particle. The latter is rapidly cleared from the eirculation by the liver. In the fasting state, the balance of lipoprotein metabolism shifts from the intestine to the liver. The latter is responsible for the synthesis of triglyceriderich very low density lipoproteins (VLDL) which are substantially smaller and denser than chylomicrons. Their initial catabolism also depends on lipoprotein lipase which converts them to cholesterol-enriched low density lipoproteins (LDL) which persist in the plasma for 3-4 days. LDL plays a key role in transporting cholesterol from the liver to peripheral tissues where the lipoprotein is subject to catabolism by at least two mechanisms. The better understood of these depends on the operation of cell membrane receptors and is responsible for the regulated delivery of cholesterol to tissues in response to their structural and metabolic needs. When demands are high,

Cholesterol transport between the liver and peripheral tissues is bidirectional since the sterol cannot be degraded in vivo but must be excreted intact in the bile. The role of reverse cholesterol transport from periphery to liver appears to be performed by another lipoprotein fraction, high density lipoprotein (HDL). In contrast to LDL, HDL seems to protect against atherosclerosis thanks to the activities of apolipoprotein AI, its major protein cormponent. The latter, representing 70% of the total FDL protein, is co-factor for the plasma enzyme lecithin:cholesterol acyltrans ferase (LCAT) which, by esterifying free cholesterol on the surface of the particle, increases its hydrophobicity and promotes its transfer to the lipid-filled core. The vacated sites on the lipoprotein surface are thereby free to accept more cholesterol from the tissues in the enviro~ent. The operation of this sterol acceptor mechaniem is limited by the lipoprotein's capacity for esterified cholesterol. In man this can be expanded many fold due to the existence in his plasma of a protein (cholesteryl ester transfer protein) which is able to shuttle esterified sterol from HDL into VLDL and LDL. Pathological Biochemistry, Royal Infirmary, Glasgow G4

A 29

S 19.03

S 20.01

THERAPEUTIC VALUE OF REDUCTION OF SERUM LIPIDS V. Manninen The medical t r e a t m e n t o f d y s l i p i d e m i a has proved i t s e f f i cacy, and v e r i f i e d b e n e f i t s are now e s t a b l i s e d f o r r e s i n s , f i b r a t e s and n i c o t i n i c acid. Three recent landmark s t u d i e s have overshadowed t h e r e s u l t s o f t h e WHO primary prevent i o n t r i a l and t h e Coronary Drug P r o j e c t (CDP). The p o s i t i v e r e s u l t s o f t h e WHO c l o f i b r a t e (25% f a l l in CHD i n c i dence were n u l l i f i e d by the excess m o r t a l i t y from non-coronary causes in t h e c l o f i b r a t e group. The CDP (secondary p r e v e n t i o n ) , on t h e o t h e r hand, revealed the dangers o f t r e a t m e n t w i t h estrogens and t h y r o i d hormones. Chalestyramine - i s a r e s i n well-known f o r i t s e f f i c a c y in lowering c h o l e s t e r o l . I t was used in the LRC-CPPT (1984), conducted by t h e NIH, USA, on h y p e r c h o l e s t e r a l e m i c pat i e n t s . 3806 men were randomised i n t o t r e a t m e n t and placebo groups. A l l men f o l l o w e d t h e same d i e t a r y regime. In t h e cholestyramine group, t h e f a l l in LDL-C was 20.3% and i n t o t a l - C 13.4%. A f t e r seven years f o l l o w - u p CHD m o r t a l i t y was down by 24% and n o n - f a t a l cardiac events had f a l l e n by 19% i n t h e t r e a t m e n t group. The H e l s i n k i Heart Study (HHS)(1987) compared g e m f i b r o z i l w i t h a placebo i n 4081 middle-aged men w i t h primary hypsrc h o l e s t e r o l e m i a but otherwise h e a l t h y . A mean f a l l i n LDLC o f 10%, T6 -35% whereas and a r i s e i n HDL-C o f 11% were seen a f t e r 5 years f o l l o w - u p i n t h e t r e a t m e n t group, which experienced an o v e r a l l 34% (p
CLINICAL P H A R M A C O L O G Y OF ACYCLOVIR: LESSONS FOR A N T I V I R A L DRUG D E V E L O P M E N T P. S. L i e t m a n The d e v e l o p m e n t of acyclovir as an antiherpes drug serves as a m o d e l of antiviral drug development and provides several lessons w o r t h considering as the general area grows. I. It is possible to create a drug that has remarkable "selective toxicity" towards the virus as contrasted to the host. 2. The selective toxicity of acyclovir is critically dependent on the intracellular activation of acyclovir to acyclovir m o n o p h o s p h a t e by a viral enzyme. 3. The intracellular p h a r m a c o k i n e t i c s of acyclovir as a p r o d r u g as well as the active m e t a b o l i t e s of acyclovir are important. 4. The conventional e x t r a c e l l u l a r p h a r m a c o k i n e t i c s of acyclovir are also important, e s p e c i a l l y with respect to oral absorption, renal elimination, and overall pharmacokinetics. 5. Rational dosing of acyclovir may include d o s i n g at more frequent intervals in order to reduce the cost of the drug. 6. Rigorous clinical trial m e t h o d o l o g y has allowed the e f f i c i e n t regulatory approval of the drug as well as a c c e p t a n c e by clinicians. It w o u l d seem reasonable to apply these lessons to the a c c e l e r a t e d search for new drugs for AIDS and other viral diseases. Division of Clinical Pharmacology, The Johns Hopkins U n i v e r s i t y School of Medicine, 600 N. Wolfe St., Baltimore, M a r y l a n d 21205, USA.

S 20.02 PROGRESS IN ANTIVIP~L TREATMENT OF RESPIRATORY INFECTIONS G.G. Jackson Much developmental knowledge and clinical experience ~ith potential and p r a c t i c a l aspects o f a n t i v i r a l therapy have c o m e from the treatment os v i r a l respiratory infections. Three f a c t o r s are i m p o r t a n t , ( 1 ) r a p i d d i a g n o s i s o f the s p e c i F i c viral etiology, (2) antivira] activity of the drugs and ( 3 ) t i m e l y pharmacologic d e l i v e r y o f a c t i v e compounds t o the s i t e os i n f e c t e d c e l l s . Interferon was f i r s t recognized in t h e p r e v e n t i o n o f experimental influenza. It's broad spectrum and host r a t h e r than v i r a l specificity gave hope o f a v o i d i n g etiologic diagnosis. But i n t e r f e r o n and i n t e r f e r o n inducers e l i c i t e d pharmacologic, l o g i s t i c and b i o l o g i c problems in t h e r a p y . Amantadlne Has among the f i r s t safe, e f f e c t i v e a n t i v ] r a l drugs f o r systemic use. I t and t h e analogue r i m a n t a d i n e remain major means f o r dru9 p r e v e n t i o n and t r e a t m e n t o f I n f l u e n z a A. Absorbed from the i n t e s t i n a l tract, the action is specific for Influenza A and mediated by i n h i b i t i o n of virus uncoatin9. The pharmacokinetics and t o x i c i t y are compound, t i s s u e and age r e l a t e d . The s y n t h e t i c nucleoside~ r i b a v i r i n , inhibits viral s y n t h e s i s and has been c l i n i c a l l y effective in t h e t r e a t m e n t o f both I n f l u e n z a A and B. Administration by small p a r t i c l e aerosol is useful in RSV and i n f l u e n z a ] pneumonia. R h i n o v i r u s common colds can be a l t e r e d using several classes o f compounds. Most promising are molecules t h a t e n t e r " t h e canyon" o f r h i n o v i r u s s t r u c t u r e and p r e v e n t necessary conformational changes in t h e v i r u s . Therapy of viral respiratory infections illustrates ne~ly recognized and d i v e r s e a n t i v i r a ] mechamisms and a range of pharmacologTc requfrements in T h e i r a p p l i c a t i o n . Medical M i c r o b f o l o g y ( V i r o l o g y ) The London Hospital Medical Colles Turner ST. London El 2AD England

A 30

S 20.03

,. Coo,ey

Abstract not received by April 30, 1989

S 21.01 IN V1VO HUMAN PET NEURORECEPTOR IMAGING D.F. Wone. L.T. Young. G. Pearlson. L. Tun~, D. Yogng, H. Sit]get. R.F. Dannals. C. Ross. A.A. Wilson. H.T. Ravert. ,l. Links. H.N. Wagner, Jr., A. Gjedde The development of radioligand receptor binding techniques over the last two decades has had a major impact on the study of neuropsychiatric disorders. Such techniques have resulted in a large number of pharmacological tools to investigate neurotransmitter receptor mechanisms. Positron emission tomography (PET) has allowed the development of techniques to image neuroreceptors in vivo in human brain through modifications of these radioligand techn-iques. Neuroreceptors which have been examined with PET include: D 1 and D2 d o p a m i n e r g i c , 5HT-2 s e r o t o n i n e r g i c , opioid, adrenergic, nicotinic and muscarinic receptor systems. , Novel neurotransmitter and receptor systems such as s i g m a and glutamate (NMDA) systems among others, are beixig Currently investigated in several PET centers. We present here some of our work e x a m i n i n g D 2 dopamine receptors in ''~ several neuropsychiatric disorders to i l l u s t r a t e this important p h a r m a c o l o g i c a l technique. We have continued to study D2 dopamine receptor density (Bmax) in manic depressive illness (MDI), Tourette's Syndrome (TS), and schizophrenia (SCZ) with improved PET methods u s i n g [C-11] 3 - N - m e t h y l s p i p e r o n e (NMSP). A multiple regression model of B m a x vs linear and quadratic terms of age was fitted to combined normal and patient data. Comparing MDI and normals, mean Bma x in psychotic MDI (28.7+12.4 pmol/g, N=8; mean age 44.1+15.9) was significantly higher than in both nonpsychotic MDI patients (18.9+_10.0, N=7; mean age 48.8+20.2) and normals (15.1• N=19; mean age 37.3+_21.0). The regression could not distinguish between nonpsychotic MDI and normals (p<0.01). However, SCZ and psychotic MDI revealed elevated B m a x compared with normals. Although mean SCZ (34.2• pmol/g, N=19; mean age 41.9-+21.8) and psychotic MDI data were not significantly different, the shape of the data curve for SCZ supported both linear and quadratic terms of B m a x falling with age. The psychotic MDI had a different intercept frown nonna.ls but B m a x did not fall with age. There was a significant positive c o r r e l a t i o n between Bmax and the degree of psychosis (Present State Exam). All 5 TS patients had elevated Bm a x values (27, 33, 36, >100 and 31 pmoles/g). Elevated D2 dopamine receptor densities occur in several neuropsychiatric disorders and may be related to complex factors t h a t - m a y include the presence of psychosis. It has been suggested that methodological issues may have contributed to reported B m a x differences in SCZ (Science 234: 1558, 1986) which include: [ C - H ] labelled metabolite corrections, plasma protein binding, serum haloperidol (HAL) measures, and brain HAL partition coefficients. Experiments were performed to address such issues: (1) Plasma l l c - N M S P metabolites measured by HPLC were compared with input function corrections in our model. Multiple regression using a fitted curve (activity vs a power function of time) showed no s i g n i f i c a n t differences between HPLC and modelled corrections (N=10 subjects). (2) There were. no differences in plasma protein binding of l l C _ N M S P in 21 patients (95.7• and 11 controls (95.6• (3) Serum HAL measures with a more sensitive (20 fold) assay correlated closely (r-0.8) with previous HAL concentrations. Bm a x estimates i n previously studied patients were still elevated when computed with these more sensitive HAL measurements. (4) HAL partition coefficients in guinea pig brain correlated closely with assumptions used in our PET studies. Our improved PET techniques continue to demonstrate elevated mean D2 B m a x in drug naive SCZ patients as demonstrated in our earlier work. In addition to these c l i n i c a l findings, v a l i d a t i o n s of assumptions and improvements in our PET methods, other models to examine neuroreceptors with PET will be presented. These include approaches using reversible ligands such as 11C-Sch23340 which binds to D1 dopamine receptors and l l c NMSP which binds to cortical 5HT-2 receptors. Our findings demonstrate the complexity of these techniques and suggest potential future applications of PET. Nuclear Medicine Tower Basement, Johns Hopkins Hospital, Baltimore, MD 21205

S 21.02 APPLICATION OF NMR TO DRUG METABOLISM IN THE BRAIN A.L. Benabid, C. Remy,M'. Decorps. S. Lotito. A. Francois. J.F. Le Bas, H. Reutenaner. Nuclear Magnetic Resonance Spectroscopy (NIvIRS) has the unique advantage of probing, atraumatically and repeatedly, the chemical composition of living organisms. A variety of nuclei as well as technical improvements provide the neuropharmacologist with a powerful tool. NMRS in vivo is able to study in vivo the effects of drugs on metabolism and also to foIIow the fate of these drugs in the organism when they are labetled by nuclear markers such as 19F or 13C. Recently, image guided spectroscopy has provided an additional possibility to localize the effects and/or the fate of the drugs in the various parts of the brain. In vivo situations actually include ceils in culture, isolated perfused organs and organs in situ. NMRS of ceils in culture is not easy to perform. Although this reduetionist approach has its intrinsic limitations, it provides a convenient modeI for the precise investigation of pharmacological effects on cell metabolism. In situ NMRS studies of the brain provide the closest conditions to physiology and allow investigations of models of nervous diseases as well as the effects of drags on the brain.The non invasive nature of NMRS makes it possible to repeat the measures without destroying the sample or even interfering with its metabolism. Some atoms have a noclea~ magnetic momentum called spin and are widely used in Biology due to tlieir metabolic importance or to their presence in drags. Each of these nuclei have a very characteristic resonance frequency in a given magnetic field. The chemical shift of this resonance frequencyhas been extensively used by the chemists to decipher the structure of molecules and is used in biological spectroscopy to recognize and observe variouschemicai species in a given sample. 31P brings informations about cellular energetic metabolism and intracellular pH. IH is very sensitive and provides important complementary metabolic data, such as lactate. 13 C gives access to the Krebs cycle and enables the tracing of metabolic pathways using 13 C-labelled molecules but is very expensive. 19 F is 'almost absent from the organism but is present in many drugs ~ d therefore used as a tracer for in vivo kinetic studies. NMRS is one of the few.techniques which "allowthe non invasive biochemical study of living tissues in their almost normal situation inside the organism, through several procedures. Chronic implantation of surface coils on the skull is particularly adapted to the study of the brain in non anesthetized animals. Another way leads to the recent and fast developing field of the spatially localized and eventually image guided spoctroscopy which make possible precise biochemical measurements in perfectly localized areas of animal and human brains. Specific appmacbes such as superfused slices and cell cultures are obviously adapted to neurophar-macologv at the cellular and/or molecular NMRS allowed the in vivo simultaneous follow-up of several metabolites. The survey of biochemical effects on organs such as the brain by potassium cyanide provides a perfect example of this use of NMRS. The metabolic changes follow a typical pattern of cellular anoxia. The time courses of pHi and lactate are decoupled under the effect of anesthetics, suggesting a partial antidotal effect which depends on the nature of the anesthetics used. Enzymatic fluxes determinations by saturation transfer are difficult experiments to perform but they open a window on the study of the drag modulated enzyme regulation in vivo. NMRS is also useful to study the effect of drugs or of therapeutic procedures on the metabolic patterns of pathological conditions such as brain ischemia. Hyperglycemia worsens the situation, as does bifemerane. Naloxone improves acidosis while metEnkephalin has no effect. Calcium antagonists prevent or correct these ischemia induced changes. Moreover, it is now possible to study the intracellular Calcium concentration by 19F NMRS. NMR spectra of the human brain have been obtained in newbom infants and in adults. The availability of 1.5 and up to 4 Tesla imaging systems allows to perform 1H brain images and to select areas from which 31P and 1H spectra are obtained using spatial localization techniques. This procedure is well suited to the follow-up of brain tumor radiation therapy or chemotherapy. The most interesting contribution of NMRS to pharmacology is to detect in vivo and on time the metabolites which are produced by the cellular processing of drugs. When the drug is labelled, with 13C or more often with 19F, the detection covers all the generated products, regardless of whether they were expected or not. Fluphenazine has been observed in vivo in the rat brain by 19F-NMRS, 7Li-NMRS has permitted to observe Lithium in the rat and human brains. Recent technical improvements should open to NMRS the highly interesting field of in vivo psychopharmaeology. The fates of Halothane and of 5FU have been investigated by 19F-NMRS During the last decade in vivo NMRS has proven to be a very powerful and performing tool in physiology and pharmacology. The limitationsare still severe in some situations and call for more technical improvements. The even more recent human applications, almost routinely performed on adequate equipments, tell us without ambiguity that these neuropharmacological studies will soon be possible in patients, for whom therapy will be more conveniently monitored and adapted. LMCEC, INS ERM U. 318, Department of Biophysics, Medical School, Joseph Fourier University of Grenoble, 38700, La Troncbe, FRANCE.

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S 21.03 REGIONAL 3-DIMENSIONAL CORRELATION OF POSITRON EMISSION TOMOGRAPIIIC AND MAGNETIC RESONANCE STUDIES OF BRAIN METABOLISM AND PHARMACOLOGY. A C Evans Quantitative interpretation of functional images (PET or SPECT) is limited by poor spatial resolution and low counting statistics. For many tracers, contrast between different brain structures is low and anatomical differentiation is difficult. Finally, normal tracer distributions can be severely distorted by such gross pathologies as stroke, tumor and dementia. Hence, the complementary anatomical information provided by CT or MRI is essential for accurate and reproducible analysis of functional images. The incorporation of anatomical information into the regional quantification of functional data can be considered as two separate problems: registration of anatomical/functional images and anatomical segmentation of the functional image. Numerous methods have been proposed for the registration of PET and MRI data. In the past these have been designed so that the same anatomical plane is scanned in both systems. Such approaches involve careful re-positioning and have encountered difficulties with uncooperative or demented subjects. Latterly, three-dimensional (3D) imaging hardware has allowed the development of volumetric acquisition and processing of data. Image registration can now be performed by postprocessing and arbitrary planes through registered image volumes generated as required. Image volume registration can be performed interactively, by matching of external head contours as observed from each modality or by direct superposition of equivalent points (fiducial or anatomical) identified within each volume. Problems of differential slice thicknesses still contribute to inconsistent partial volume effects and sampling artifacts. This is particularly of concern for small structures adjacent to CSF such as the caudate nucleus, a structure which plays a central role in PET studies of motor and psychiatric disorders. Once matched MRI/PET datasets are obtained, the specific zones from which functional measurements will be taken have to be identified, preferably according to a standardized classification of neuroanatomical regions. Methods for matching computerized regiomof-interest (ROI) atlases to the anatomical data have been explored by a number of eentres. Approaches range from computer-controlled deformation of a normal atlas to fit the image, using some objective matching criteria, to more interactive procedures which sacrifice some objectivity to allow detailed local modification and inclusion of lesion structures. At the MNI, work has been continuing on the 3D correlative imaging and analysis of MRI, PET, CT and digital subtraction angiography (DSA). Using a 1.5 Tesla MRI scanner and a 15-plane high-resolution PET scanner, we register MRI and PET volumes with a point-to-point mapping algorithm which minimizes the mean square distance between paired points. Examples of combined anatomical/functional images will be shown for various diseases, including stroke, tumor and degenerative conditions, and for various systems, including glucose metabolism, blood flow and dopamine neurotransmission. To segment the PET data, we have previously developed a computerized brain atlas which is modified interactively to fit each subject's brain, based on the MRI image. Comparison of this approach with direct interpretation of the PET images demonstrated a mean reduction in inter-observer variability by a factor of 2-3 for both localization and functional measurement across a set of 25 brain structures. This 2D approach required careful planning to obtain matched planes from MRI, PET and the brain atlas. We have now developed the means to display and modify a 3D version of this methodology, such that MRI, PET and VOI structures can be matched in three dimensions. McConnell Brain Imaging Unit, Montrgal Neurological Institute, Montreal, Qudbee.

S 22.01 TREATMENT OF MYOCARDIAL INFARCTION WITH RT-PA M . L . L . Simoons. MD, FESC~ F A C C Thrombolytic therapy has now been established to restore bloodflow to t h e ischemic myocardium in the majority of patients, which limits infarct size, and preserves cardiac function. In comparison with placebo, thrombolytic therapy improves early and longterm survival after myocardial infarction. The most widely tested thrombolytic drugs are streptokinase (SK) and rtPA, and both have been shown to be effective. In comparative studies rt-PA appeared more effective than SK to achieve coronary reperfusion (62 vs 31% of patients) and coronary patency (70 vs 55% of patients). The most widely used dose of rt-PA is iO0 mg administered over 3 hrs (i0 mg bolus, 50 mg/hr, 40 mg/2 hrs). Other regimens presently under evaluation may yield higher patency rates. Reocclusion can occur after thrombolytic therapy, and has been reported in 718%. Concomittant treatment with heparin and aspirin is recommanded to prevent reocclusion. Bleeding complications are common at the sites of vascular access. However, intracrananial hemorrage is infrequent (0.5-1.0% of patients). I n large placebo controlled trials stroke was not more prominent after SK or rt-PA than after placebo. Infarct mortality has been reduced dramatically due to the introduction of thrombolytic therapy. The lowest mortality rates have been reported in studies with rt-PA, ranging from 3% to 7% at 2 to 4 weeks ! A series of studies have demonstrated that systematic immediate or' early angiography and additional revascularisation are not mandatory in patients treated with rt-PA. Such additional invasive therapy is only indicated in 5 to 20% patients who develop recurrent myocardial ischemia.

S 22.02 RECOMBINANT PRO-UROKINASE: MOLECULAR PROPERTIES AND THERAPEUTIC PROFILE L. Floh~ Saruplase, i.e. the non-glykosylated full-length urokinase-type plasminogen activator, is obtained from genetically transformed Escherichia coli (L. Floh~, Eur. Heart J. 6, 905, 1985). In some respects saruplase behaves like an inactive zymogen, but it physiologically activates plasminogen in the presence of fibrin (H.J. Lijnen et al., J. Biol. Chem. 261, 1253, 1986). Correspondingly effective fibrinolysis without induction of a lyric state can he achieved in animal models of thrombosis or embolism. As evident from a multi-center double-blind streptokinase-controlled study in 401 patients (communicated by J. Meyer on behalf of the PRIMI study group at 61st Scientific Sessions of the American Heart Association, Washington, D.C., November 14-17, 1988) saruplase is clinically effective in the treatment of evolving myocardial infarction: Application of 80 mg saruplase induces rapid recanalization of infarct-related arteries, results in high patency rates (72 % at 60 min after onset of treatment) and is associated with a low incidence of reocclusions (i or 5 % depending on definition of subgroup), bleeding complications requiring transfusions(4 %) and in-hospital mortality (3.5 %). It is concluded that saruplase compares favourably with the fibrinolyric drugs available so far. Grfinenthal GmbH, Forschungszentrum, Zieglerstra~e 6, D-5100 Aachen

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S 22.03 Abstract not received by April 30, 1989

be f i t t e d ~o t h e n a t u r a l course of the disease. To r e d u c e i n s u l i n r e s i s t a n c e the t h e r a p e u t i c s t e p s r e q u i r e d s t a r t w i t h n o r m a l i z a t i o n of body w e i g h t , reduced i n t a k e of saturate~d f a t and p h y s i c a l e x e r c i s e , i f a p p l i c a b l e . Only thereafter pharmacologic intervention by betacytotropic s u l f o n y l u r e a may be i n i t i a t e d , p r e f e r a b l y in t h e n o n - o b e s e , h y p o i n s u l i n e m i c patient. In c o n t r a s t , b i g u a n i d e s , which may improve g l u c o s e uptake by muscule t i s s u e , are r e s e r v e d f o r obese NIDDMs, w h i l e a l p h a glucosidase inhibitors are r e s t r i c t e d to improve postprandial glycemia after polysaccharide ingestion. Insulin treatment, however, should o n l y oe i n i t i a t e d once b l o o d glucose values consistently remain above the t a r g e t range d e s p i t e the p a t i e n t ' s strict adherence t o a p p r o p r i a t e t r e a t m e n t . I.Medizinische Universit~tsklinik, L a z a r e t t g a s s e 14, A-I090 Wien A u s t r i a .

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RATIONAL TREATMENT O'F NON-INSULi~ D~ENDENT (TYPE 2) DIABETES: DOES IT EXIST? W.Waldh~usl A v a i l a b l e forms of t r e a t m e n t of n o n - i n s u l i n d e p e n d e n t d i a b e t e s (NIDDM) r e l y on n o r m a l i z a t l o n of oouy w e i g h t in t h e obese, on administration of u r a l a n t i d i a b e t i c agents including sulfonylureas, b i g u a n i d e s and possibly inhibitors of i n t e s t i n a l p o l y s a c c h a r i d e a b s o r p t i o n as w e l l as on i n s u l i n i f any o t h e r form of t r e a t m e n t f a i l s to r e a s o n a b l y improve c a r b o h y d r a t e m e t a b o l i s m . Such approach p e r m i t s good m e t a b o l i c c o n t r o l o n l y in about 25% of a l l NIDDMs. To improve such u n s a t i s f a c t o r y therapeutic outcome one has to u n d e r s t a n d the h e t e r o g e n o u s causes of i n s u l i n i n d e p e n d e n t h y p e r g l y c e m i a , commonly r e f e r r e d to as NIDDM. I t is c h a r a c t e r i z e d by f a s t i n g h y p e r g l y c e m i a due to i m p a i r e d g l u c o s e c l e a r a n c e and i n c r e a s e d h e p a t i c g l u c o s e p r o d u c t i o n , which i s attributed to e x c e s s i v e p r o v i s i o n of g l u c o n e o g e n i c p r e c u r s o r s from p e r i p h e r a l t i s s u e s , p r e d o m i n a n t l y muscle. A s s o c i a t e d i n s u l i n r e s i s t a n c e may be p o t e n t i a t e d by dietary habits causing a disproportionate rise in plasma s a t u r a t e d f a t t y a c i d c o n c e n t r a t i o n . In a d d i t i o n , NIDDM d i s p l a y s a l o s s of t h e c e p h a l i c phase of i n s u l i n r e l e a s e as w e l l as n y p e r - and h y p o i n s u l i n e m i c h y p e r g l y c e m i a . In c r o s s - s e c t i o n a l s t u d i e s , more marked n y p o i n s u l i n e m i a was seen w i t ~ more s e v e r e h y p e r g l y c e m i a . Such i m p a i r e d i n s u l i n s e c r e t i o n is o n l y o b s e r v e d in r e s p o n s e to g l u c o s e , but not to a r g i n i n e and may be due t o a genuine d e f e c t of t h e B - c e l l g l u c o r e c e p t o r . A g a i n s t t h i s background r a t i o n a l t r e a t m e n t of NIDDM has to be a d i f f i c u l t task~ which has to

Antiarrhythmic agents. T. Meinertz, MD Allg. Krankenhaus St. Georg, Lohmuehlenstr.l ,2000Hamburg I Long-term antiarrhythmic therapy is mandatory in patients with lethal or malignant ventricular arrhythmias, i.e. ventricular arrhythmia~ that produce a hemodynamic consequence (severe presyncope, syncope or cardiac arrest). Most often the underlying arrhythmia is sustained ventricular tachycardia or ventricular fibriletion. These patients should always be evaluated and treated in the hospital by continuous electrocardiographic monitoring and by invasive electrophysiologic t~sting. Potentially lethal ventricular arrhythmias, i.e. frequent ventricular premature complexes, ventricular pairs aud nonsustained ventricular tachycardia, although not producing hemodynamic consequences, occur in the presence of structural cardiac disease. Patients with this combination of factors have a moderately increased risk of sudden cardiac death. AIthough it is hoped that antiarrhythmic drug therapy will prevent sudden cardiac death by reducing ventricular premature complexes and nonsustained ventricular taehycardia also in this group of patients, the final proof of this hypothesis is still lacking and currently undergoing evaluation in several controlled clinical trials. Whereas patients in this category with less overt degrees of ventricular dysfunction can safely be treated as outpatients, patients with severe ventricular dysfunction should be evaluated and managed in the hospital. In patients with potentially lethal ventricular arrhythmias long-term antiarrhythmic therapy isguided by Holter monitoring. Patients with benign ventricular arrhythmias have the most favorable prognosis: Minimal to no risk of sudden cardiac death. Patients with this type of arrhythmia are characterized as having no important structural cardiac disease and no arrhythmia related hemodynamic consequences. Elimination of symptoms should he the therapeutic goal if present to a degree that interferes with the patients lifestyle. In general these patients can be appropriately managed in the out.-patient setting usin~ noninvasive Hol-

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S 24.01 t e r monitoring. Whenever possible long-term antiarrhythmic therapy should be avoided. Ideally the etiology of a ventricular arrhythmia and its provoking stimulus should be identified, and the arrhythmia treated specificially. In most cases, however, the etiology and the provoking stimuli of an arrhythmia cannot be identified, and treatment becomes empiric. The characteristics of a ventricular arrhythmia are recognized as inaccurate predictors for a particular patient's response to antiarrhythmic therapy: "Every attempt at treatment is an uncontrolled experiment". There are, however, certain clinical indications that I drug may be preferable to others, if only because of reduced likelihood of adverse effects. The effectiveness of the conventional or first -generation antiarrhythmic agents is unpredictable and many patients faile to respond to treatment. The adverse effects of these drugs alsolimit their use especially during longterm treatment. Data from recently published controlled clinical trials suggest that newer antiarrhythmic agents such as mexiletin or class l-C-agents (flecainid, propafenon, encainid)or sotalo] are more predictably effective with a lower incidence of adverse effects. Treatment with a combination ofan~arrhythmic agents should be considered if several single agents were proven to be ineffective or if additional protection is required for patients with a life-threatening arrhythmia. A combination of agents allows lower dosages to be used, thus minimizing adverse systemic and noncardiac affects, while allowing additive electrophysiologic effects. Long-term tolerance is also improved by a reduction in dose-related adverse effects. Up to now very few data are available concerning the use of combination treatment during long-term therapy.

S 23.03 LONG TERM MEASUREMENT OF ANTI-RHEUMATIC DRUG EFFECTS IN RHEUMATOID ARTHRITIS J, R. Kirw~n Rheumatoid arthritis (RA) affects 2% of the population. Half of these seek medical attention and may suffer severely. The onset and pattern of RA are very variable. For many patients the disease is slowly or rapidly progressive. Bouts of inflammatory activity add to an increasing burden of structural joint damage. In the past, efforts to assess drug effects have avoided the difficulties such variation and progression add to therapeutic assessment by concentrating on measuring the biochemical and clinical evidence of disease processes. This has distracted investigators from the need to assess disease outcome and has resulted in relatively short term evaluations of efficacy. In practice, RA is a long-term disease and therapeutic trials should take this into account. Long term trials must address the need to maintain treatment over long periods and the ethics of placebo control. They must measure many aspects of the patients' quality of life-disability, discomfort, social and economic costs - and must be sufficiently powerful to detect clinically meaningful benefits. Studies of sufficient size and length are possible and are currently being conducted. Their design and rationale will be reviewed. Rheumatologists are facing the problem of long-term outcome assessment and have been developing and using new assessment procedures. Rheumatology Unit, University Department of Medicine, Bristol Royal Infirmary, Bristol BS2 8HW, U.K.

PHANMACODYNAMIC MODELLING N.H.G. Holford Si~ole models of drug action are w~ll established in theory and are widely used to describe in vitro pharmacological phenomena. These models, based on the Law of Mass Action, provide a quantitative basis for the interaction of drugs with binding sites and the subsequent transduction to an observable pharr~cological response. They have come to be used to describe in vivo actions of drugs although the assumptions on which they rest are not usually verifiable. More sophisticated models describing the time course of drug action in vitro were developed many years ago at the time the "biophase" concept was introduced. The application of models incorporating time dependence has been most prominent in descriptions of drug effects in vivo with some striking insights into the relationship between structure, function and pharmacology. Models of drug interaction can easily become conlolex. However, the application of simple models for simple competitive antagonism can help understand the extent and time course of commonly used medicines e.g. beta adrenocept or antagonists and angiotensin converting enzyme inhibitors. Some drug actions are best described as quantal, the action is either present or absent e.g. anti-arrhyt~nic effects. Although a quantal model may be needed to describe the observable drug action an underlying continuous action may best ezqolain the mechanism e.g. altered cardiac conduction or repolarization. An important application of pharmacodynanic models is the prediction of drug effects in vivo which are not directly observable. For exa~01e, the cumulative drug effect may be predicted from the integral with respect to time of a readily observed phenc~nenon. The desired therapeutic effect may be more closely related to some integral of the effect rather than the instantaneous effect itself. This concept has been applied to understanding the effects of glucocorticoids. Holford NHG. Drug effect prediction ~n u~uo. in Systems & Control ~ncyclopedia. pp. 1244-1249 Edited by MG Singh. Perg~non Press, Oxford. 1988. Department of Pharmacology and Clinical Pharmacology, University of Auckland School of Medicine, Private Bag, Auckland, New Zealand

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POPULATION PHARMACOKINETICS

NEW APPROACHES TO EVALUATING THE ABSORPTION PROPERTIES OF THE GASTRO-INTESTINAL T R A C T D. Brockmeier Drug therapy is predominated by oral formulations, since the oral route is the most convenient and popular way o f applying a drug. However, the fate of the drug molecules in the gastro-intestinal tract and during absorption can significantly influence the safety and efficacy of drug therapy. Particularly with extended release formulations or drugs with slow dissolution rates (low solubility) it is important to know whether the drug is absorbed throughout the gastro-intestinal tract with the same rate constant or whether the rate constant differs markedly from site to site. The following large-scale invasive techniques have been used to study the site-dependent absorption of drugs and nutrients: I. intubation with multi-luminal catheters (with and without occlusion) and endoscopy, II. HF-capsules with an extracorporal trigger for drug release, IIl. scintigraphic techniques in combination with the deconvolution method. The intubation technique and the HF-capsules have demonstrated for a small number of drugs that the rate and amount of absorption may be different for the various segments of the gastro-intestinal tract. Both higher and lower rate constants of absorption have been observed for the lower part as compared to the upper part of the gastrointestinal tract; with some drugs, e.g. furosemide, the rate of absorption falls almost to zero in the lower part. Markedly smaller rates of absorption in the lower part explain the variable bioavailability observed. The smaller the rate constant of absorption in the lower part, the greater the variability in bioavailability. Recently a new, less invasive approach has been elaborated to study the absorption properties of the gastro-intestinal tract. It compares the in vitro results of drug dissolution with the hypothetical in vivo profile of dissolution in a detailed point by point manner (continuous in vitro/in vivo correlation). It is essenti~il for this approach that the in vitro dissolution profiles of the extended release formulation are isomorphic or at least homomorphic under reasonable variation of the dissolution conditions and/or apparatus. In this context, homomorphism basically means that the dissolution profiles obtained under different test conditions can be superimposed by linear transformation of the time axis. In the Clinical part of the new approach, such formulations have to be studied in a crossover design with an oral solution in order to estimate the hypothetical in vivo dissolution profile by deconvolution. With some drugs, i.v. application may he used instead of an oral solution. The homomorphism of in vitro dissolution profiles can be determined by comparing those times required by the various dissolution test methods until the same fractions are dissolved; times but not amounts have to be compared in this method. With homomorphic profiles, the correlation of times related to identical fractions dissolved will result in a straight line. The in vitro and the hypothetical in vivo dissolution are compared in the same way (continuous in vitro/in vivo correlation). This correlation will result in a straight line provided I. the true in vivo dissolution profile is homomorphie with the various in vitro dissolution p r o files and II. the absorption properties do not change while the f o r mulation is moving down the gastro-intestinal tract. The former prerequisite is most likely to be met if the formulation shows homomorphic in vitro dissolution profiles. Homomorphism of in vitro and in vivo dissolution profiles has been confirmed for some formulations by scintigraphy. Deviations from the straight line relationship therefore indicate changing absorption conditions along the gastro-intestinal tract. The method has been applied to data from different drugs for which the extended release formulation studied has shown homomorphie properties in the in vitro test. The data were collected from internal company studies as well as from the literature. The evaluation e m ployed only the data of drugs for which the absorption from different segments of the gastro-intestinal tract has also been studied using one of the above mentioned techniques. The comparison with these results shows that the new method is as sensitive as the more invasive techniques. It is concluded that a carefully designed pharmaceutical formulation can be used as a test probe to screen the absorption properties of the gastro-intestinal tract for the drug considered. The new approach o f fers a wide field of applications, e.g. since the clinical part requires only blood sampling, the method can be used in patients and even the influence of a gastro-intestinal disease on absorption may be considered. Hoeehst AG, Klinische Forschung, Postfaeh 800320, D-6230 Frankfurt/M-80, FRG

S. Vozeh and K. Fattinger Population pharmacekinetics are being applied by an increasing number of investigators. This is primarly due to the fact that since several years a generally available software (NONMEM) exists to perform this complex data analysis. The important advantages of the population pharmacokinetics, compared to "individual" approaches, are the use of large patient samples from a representative population and the estimation of the variability of the pharmacokinetic parameters. Both characteristics are essential if the results are to be used for designing optimum dosing regimens. For reliable a priori dosing regimens that should result in a large proportion of patients within a desired concentration range, it is important that the data have been obtained in patients actually treated with the drug and that interindividual pharmacokinetic variability had been taken into account. A population average value within the "therapeutic" range by no means precludes the possibility that a large proportion of patients will have either toxic or subtherapeutic concentrations. Quantitative estimates of the interindividual variability based on a representative patient sample are also needed for an efficient individual dose adjustment if therapeutic drug monitoring is used with Bayesian feedback. Population pharmacokinetics represent also a powerful tool for an exploratory analysis to investigate factors that may influence the pharmacokinetics of a drug. These advantages have, however, their costs: assumptions about the pharmacokinetic and statistical model, complex data analysis requiring high level of expertise and experience, and the possibility of bias inherent to every exploratory data analysis. Both violation of the model assumptions and the presence of bias can often remain undetected during the analysis. For this reason, it is very difficult, if not impossible, for the data analyst (or a reviewer) to be sure that the analysis has been performed "correctly" and that no important bias is present. It has been therefore suggested that the results of a population data analysis be validated on a data set that was not included in the analysis. Ideally this should be done on a separate patient sample. The different possible approaches for validation of the results will be discussed with the help of concrete examples. Although the presentation will concentrate on only one method used in population pharmacokinetic analysis (the first order method implemented in NONMEM) it should be pointed out that other approaches have been proposed (e.g. the non parametric maximum likelihood method) that may significantly influence the further development in this field. To our knowledge, NONMEM is presently the only method for which software is available. Division of Clinical Pharmacology, University of Basel and Intercantonal Office for the Control of Medicaments, Erlachstrasse 8, CH-3012 Bern / Switzerland

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S 25.01 IMMUNOPATHOGENIC MECHANISMS OF HIV INFECTION P. Biberfeld. Recent c l i n i c a l as well as experimental findings seem to indicate a broader eel1 tropism of HIV than f i r s t recognized. Thus antigen presenting c e l l s of the dendrit i c c e l l system~ monocytes-macrophages, bone marrow stam celZs, gut-mucosal c e l l s of the nervous system in addition to T-helper c e l l s may become targets and mediate pathogenic e f f e c t s in various tissues during HIV i n f e c t i o n . The rate of i n f e c t i o n seems to depend on HIV-CD4 i n t e r a c t i o n but alternate/complimentary mechanisms off i n f e c t i o n may be of importance in vivo. Apart from d i r e c t e f f e c t s of HIV, other pathogenic mechanisms based on humoral and c e l l mediated reactions to HIV a n t i gens in vivo may be implicated in HIV associated disease. In addition the immunodeficieney of HIV i n f e c t i o n s allows the manifestation of pathogenic agents and mechanisms leading to opportunistic i n f e c t i o n s and tumors. Thus the therapeutic requirements for treatment o f HIV i n f e c t i o n s are by necessity disparate and complex. Immunepathology Lab., Department of Pathology, Karolinska I n s t i t u t e & Hospital, S-I04 Oi STOCKHOLM, Sweden.

cases may double or triple. The urgency of the HIV/AIDS epidemic prompted the establishment of the WHO Global Programme on AIDS (GPA), with the objectives of preventing HIV transmission, reducing the morbidity and mortality associated with HIV infection, and unifying national and international efforts against AIDS. Biomedical Research Unit, Global Prograrmme on AIDS, World Health Organization, Avenue Appia, 1211 Geneva 27, Switzerland

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WORLDWIDE EPIDEMIOLOGY OF HIV-INFECTION J. Esparza, J. Chin and J. Mann As of April, 1989, more than 140,000 cases of AIDS have been officially reported to the World Health Organization (WHO) from 145 countries. However, WHO estimates that about 450,000 cases may have already occurred globally. Large numbers of cases have been reported from North America, Latin America, Oceania, western Europe and areas of central, eastern and southern Africa. Available serological evidence indicate that, at the present time, there are between five million and ten million people infected with the human immunodeficiency virus (HIV), worldwide. From the analysis of the seroprevalence data and the number of reported cases, three broad epidemiological patterns of HIV/AIDS can be distinguished. In areas with Pattern I (North America, western Europe, Oceania, and parts of Latin America), HIV began to spread extensively in the late 1970's and most cases occur among homosexual or bisexual males and urban intravenous drug users, with an overall prevalence of less than I% but of over 50% in some groups of persons practising high-risk behaviours. In Pattern II areas (some Sub-Saharan African countries and, increasingly, in some parts of Latin America and the Caribbean), the virus also began to spread in the 1970's; most cases occur among heterosexuals with an overall seroprevalence of more than I% and up to 30% of males and females in the sexually active groups of some large urban areas. The male to female ratio is approximately 1:1, and as a result, mother-to-infant transmission is common. In Pattern III areas (eastern Europe, North Africa, Middle East, Asia and most of the Pacific), HIV was introduced in the early to mid-1980's, with only small numbers of cases reported, the majority in persons who had travelled to Pattern I or Ilareas, who had received contaminated imported blood products, and increasingly among intravenous drug users. Over one million cumulative cases of AIDS are projected by the end of 1991 and by the mid-1990's, the toll of AIDS

C L I N I C A L P H A R M A C O L O G Y : A N E S S E N T I A L S T E P IN ANTI-HIV DRUG DEVELOPMENT D.M. K o r n h a u s e r The e p i d e m i c of H I V i n f e c t i o n has s t i m u l a t e d a w o r l d - w i d e s e a r c h for e f f e c t i v e d r u g t h e r a p y . In v i t r o s y s t e m s c a p a b l e of t e s t i n g large n u m b e r s of c o m p o u n d s for a n t i - H I ~ a c t i v i t y have been developed; many compounds with anti-HIV activity have been identified. However, the development of therapeuticagents from active compounds has been difficult. A n i m a l m o d e l s of H I V d i s e a s e in w h i c h c o m p o u n d s c a n be t e s t e d for in v i v a t h e r a p e u t i c e f f i c a c y are l i m i t e d . Consequently, compounds with anti-HIVactivity ,have b e e n a d m i n i s t e r e d to m a n e a r l y in the drug development process and these p h a r m a c o l o g i c s t u d i e s h a v e s e r v e d to i d e n t i f y the t o x i c i t i e s and a c t i v i t y of the c o m p o u n d s in viva. The d e s i g n of t r i a l s has b e e n c o m p l i c a t e d by the v a r i o u s s t a g e s o f H I V i n f e c t i o n , the u n p r e d i c t a b l e p r o g r e s s i o n of the d i s e a s e in i n d i v i d u a l s u b j e c t s , t h e s e r i o u s n a t u r e of the illness, a n d the d i f f i c u l t y in i d e n t i f y i n g s u i t a b l e e n d p o i n t s for e v a l u a t i n g e f f i c a c y a s i d e f r o m d e a t h or the d e v e l o p m e n t o f opportunistic infections. Fundamental principles ofclinical pharmacology r a n d o m i z a t i o n of s u b j e c t s , b l i n d i n g of o b s e r v e r s a n d i n c l u s i o n of p l a c e b o c o n t r o l s h a v e b e e n i m p o r t a n t f a c t o r s in the d e s i g n of successful studies. When these principles have been neglected, study results have been a m b i g u o u s or u n i n t e r p r e t a b l e . S t u d i e s in H I V - i n f e c t e d s u b j e c t s e m p l o y i n g m a n y d i f f e r e n t d r u g s h a v e d e m o n s t r a t e d t h a t i__nn v i t r o a s s a y s of a n t i - H I V a c t i v i t y a n d e x p e r i m e n t s in a n i m a l m o d e l s c a n n o t

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Cont. S 25.03 s u b s t i t u t e for w e l l c o n d u c t e d c l i n i c a l studies. F a i l u r e to d e m o n s t r a t e in v i v o e f f i c a c y (HPA 23), u n a c c e p t a b l e t o x i c i t y (suramin) a n d a p r e v i o u s l y u n r e c o g n i z e d toxicity (dideoxycytidine) of the c o m p o u n d , and s p e c i e s s p e c i f i c m e t a b o l i s m (zidovudine) h a v e a l l b e e n i d e n t i f i e d in t r i a l s of a n t i - H I V a g e n t s in i n f e c t e d s u b j e c t s . These examples u n d e r s c o r e the r e q u i r e m e n t for t h o r o u g h i n v e s t i g a t i o n s of a n t i - H I V c o m p o u n d s in infected subjects. Careful clinical p h a r m a c o l o g y p e r f o r m e d e a r l y in d e v e l o p m e n t and a p p l i e d to t r i a l s of a c t i v i t y a n d t h e r a p e u t i c e f f i c a c y w i l l s p e e d the a v a i l a b i l i t y of n e w t h e r a p e u t i c a g e n t s w h i l e the lack of r i g o r in h u m a n s t u d i e s w i l l l e a d to u n c e r t a i n t y a b o u t the b e n f i t s of s p e c i f i c a g e n t s a n d d e l a y the a p p e a r a n c e of n e w d r u g s . Division of Clinical Pharmacology, Johns H o p k i n s U n i v e r s i t y S c h o o l of M e d i c i n e , O s l e r 525, 600 N. W o l f e St., B a l t i m o r e , MD U S A 21205.

In our progress towards the development of an effective chemotherapy for AIDS, we observed the following: I. Among the anionic substances, ATA has a specific affinity for the CD4 receptor, thus preventing the attachment of EIV to the CD4 cells. That ATA selectively interacts with CD4 could be ascertained by using specific monoclonal antibody to cell surface markers: only the binding of 0KT4A (leu3A) was prevented by ATA. II. Various ddN analogues exhibit a selectivity against HIV that is comparable to that of azidothymidine (AZT), and some of these ddNs (i.e. D4T, FddCiUrd) are markedly less toxic than AZT for bone marrow cells. Unlike AZT which piles up in the cells as AZT 5'-monophosphate because the latter blocks thymidylate kinase that is needed for its further conversion to the 5'-di- and 5'-triphosphate, D4T and FddCiUrd do not show an accumulation of their 5'-monophosphate forms. III. PMEA has greater anti-retrovirus activity than AZT in murine retrovirus models in rive, end its therapeutic potential as an anti-AIDS drug is now being explored in cats and monkeys (against feline AIDS and simian AIDS, respectively). IV. Unlike AZT and other ddN analogues, sulfated polysaccharides (and sulfated polymers in general) are able to block syncytium formation between HIV-infected and uninfected cells. We have recently demonstrated that this syncytium formation is accompanied by a selective destruction of the uninfected (target) cells by the HIVinfected (agressor) cells. In this respect, one chroniwipe out hundreds if net cally HlV-infected cell ma thousands of uninfected CD4 cells. This phenomenon may play an important role in the pathogenesis of AIDS, in that it may explain the dramatic depletion of 0D4 + T-iymphocytes in AIDS patients. Thus, effective means that block this phenomenon, such as the sulfated polymers, may be therapeutically advantageous over those compounds (i.e. AZT) that do not affect syncytium formation. Rega Institute for Medical Research, K.U.Leuven, i0 Minderbroedersstraat, B-3000 Leuven, Belgium.

S 25.04

S 26.01

FUNDAMENTAL ASPECTS OF ANTI-AIDS CHEMOTHERAPY Erik De Clereq In our approaches to the chemotherapy of AIDS, we have established the following classes of compounds as potent and selective inhibitors of HIV replication : Class I. Anionic substances such as suramin, Evans Blue, aurintricarbo~ylic acid (ATA), fuchsin acid, glycyrrhizinic acid and bile acid derivatives. Class II. DideoxTnucleoside (ddN) analogues such as 2',3'-didehydro-2',3'-dideoxycytidine (D4C). 2',3'-didehydro-2',B'-dideoxythymidine (D4T), 3'-azido-2',3'-dideoxy-2,6-diaminopurineriboside (AzddDAPR) and 3'-fluoro2',B'-dideoxy-S-chlorouridine (FddCIUrd). Class III. AcTclic nucleotide analogues such as the phosphonylmethoxyethylpurine derivatives 9-(2-phosphonylmethoxyethyl)adenine (PMEA) and 9-(2-phosphonylmethoxyethyl)-2,6-diaminopurine (PMEDAP). Glass IV. Sulfated polysaccharides such as dextran sulfate, pentosan polysulfate, %-carrageenan, mannan sulfate, heparin and various non-anticoagulant derivatives thereof, and synthetic polymer sulfates such as polyvinylalcehol sulfate and copolymers thereof with acrylic acid. Whereas class I compounds may be inhibitory to both virus adsorption and reverse transcription (or yet other processes), class II and class III compounds are assumed to he specifically targeted at the reverse transcriptase. To this end, class II and class III compounds must be phosphorylated intracellulerly to their 5'-triphosphate or diphosphorylphosphonate derivatives, respectively. Sulfated polyacoharides and sulfated polymers in general (class IV) would owe their anti-HIV activity mainly to inhibition of virus adsorption to the cells. Those compounds that block virus binding to the cells, and thus interfere with the interaction between the viral envelope glycoprotein gpl20 and the cellular CD4 receptor, may also be expected to block giant cell (syncytium) formation between HIV-infected cells (expressing gpl20 at their surface) and uninfected cells (bearing the CD4 receptor).

CHANGING STRATEGIES IN WHOLE ANIMAL LONG-TERM CARCINOGENICITY TESTING R. Kroes Several decades have emerged since Dr. Arnold Lehman led actions to provide better information on drug safety. Carcinegenicity testing has been one of the requirements in most, if not all, national regulations. A number of drugs, primarily used as anticancer agents, hut also used as therapeutic agents (incl.hormonal) otherwise, have been found to be human carcinogens, whereas others are considered to be suggestive for such an effect. These findings have had great influence on todays caroinogenicity testing for chemicals and for drugs in particular. Todays testing should include a careful consideration of the carcinogenic mechanisms involved, in order to provide the necessary and indispensable basis for evaluation and regulatory decisions with scientific merit. Short term tests, especially those aiming at detecting genotoxieity are of great help in the prephase of carcinogenicity testing, but certainly cannot be considered conclusive by themselves. Their results may give however, guidance for the sequence and design of in vivo carcinogenicity testing. Carcinogenicity testing, its past, current status and development will be discussed. National Institute of Public Health and Environmental Protection, Antonie van Leeuwenhoeklaan 9, P.O.Box ], 3720 BA Bilthoven, The Netherlands.

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S 26.02

S 26.03

PREDICTIVE VALUE OF SHORT-TERM TESTS : AN OVERVIEW. M.Roberfroid

APPROACHES OF A HEALTH AUTHORITY TO RISK ASSESSMENT OF NEW AND OLD DRUGS R. Bass The results of risk assessment by health authorities are often seen only as risk-benefit decision on the marketing authorization/status of a drug, i.e. under well defined conditions and on a ease by case basis. Such decisions should ensure that patients are provided with efficacious drugs and are prevented from using unsafe ones. This scientific balancing of risk and benefit has approx, the same legal background world-wide: health authorities are expected to presume that a drug is of poor quality, unefficacious and unsafe - unless proven otherwise. For new drugs the data base to be made available to prove absence of unacceptable potential risks for man stems mainly from pre-clinical routine animal studies. As soon as unacceptable risk potentials occur, they need to be verified/falsified. Whereas the necessary routine studies can be derived from guidelines, the type and extent of testing for trouble-shooting is often unpredictable. For major risk areas to be assessed by toxicological studies (tumorigenicity, mutagenicity, embryotoxicity, other irreversible toxic effects) the human counterpart will not be available for risk assessment, at least not for new drugs. Correlation between animal and man then depends on (quantitative) comparison, e.g. through pharmacokinetics. Risk assessment will yield a decision, independent on the availability of the amount and usefulness of data at a pre-set point in time and independent on the data which may be obtained in the future. Since reasoned courage barely exists, the possible error from planning, performing, evaluation and risk assessment is always placed on the safe side thus overruling case by case scientific expectation. Institut ftir Arzneimittel des Bundesgesundheitsamtes, Seestr. 10, D - 1000 Berlin 65

To evaluate the t o x i c i t y o f a drug is a very complex and r i s k y task. I t is the o b j e c t i v e of modern t o x i c o l o g y to challenge that p r e d i c t i o n by e x t r a p o l a t i n g r i s k f o r humans from data obtained using in V i t r o or in Vivo animal models. Carcinogenicity is one of the major r i s k which need to be e v a l u a t ~ w i t h great caution. One o f the o b l i g a t i o n o f t o x i c o l o g y today is to become more s c i e n t i fic. Indeed most of the protocols and most practices f o r t o x i c i t y t e s t i n g (including l i f e - l o n g c a r c i n o g e n i c i t y ) have no or only a very weak s c i e n t i f i c basis. They have been used f o r long and repeated practices have validated t h e i r use. To become more s c i e n t i f i c , t o x i c o l o g y has to develop and to use tests based on precise knowledge of the mechanisms of the e f f e c t s which cause that p a r t i c u l a r toxicity. During the l a s t 15 years, short-term t e s t s , usually based upon mutagenicity or some other response to DNA damage, have been developped with the view to detect possible carcinogens. Yet besides a l l the progress that has been made the s i t u a t i o n concerning the deployment o f the tests to predict the carcinogenic potential o f drugs in a r e g u l a t o r y context is s t i l l confused. In p a r t i c u l a r theim use in p r e d i c t i n g wether or not a substance has the a b i l i t y to cause cancer in humans is questionned mostly because that p r e d i c t i o n appears not to be as accurate as i t was expected in e a r l y days. Indeed from 90% at that time, the accuracy f i g u r e s have declined and the most recent study indicated that in the Ames Salmonella assay t h e ' p r e d i c t i v i t y of a mutagenic response f o r carcinogenic i t y was 75% and of a non-mutagenic response f o r non-car c i n o g e n i c i t y 48%. With an expert l i k e B.A. Bridges, one may argue that most o f the problems started to a r i s e whenthese studies became routine tests conducted under defined protocols rather than as experiments designed to t e s t s p e c i f i c hypotheses. The s c i e n t i f i c dimension these tests had brought to t o x i c o l o g y appeared to be l o s t due to the development o f a check l i s t approach. This trend must be reversed i f the proper place o f shortterm tests is to be r e a l i s e d . I t is now abundantly cl ear t h a t an evaluation o f p o t e n t i a l c a r c i n o g e n i c i t y f o r an agent requires an integrated assessement o f a l l a v a i l a b l e informations. In a r e g u l a t o r y context, the choice o f short-term t e s t must be founded on basic s c i e n t i f c p r i n c i ples and may not necessarily be the same f o r each agent. Some f a c t o r s w i l l be considered that must be taken into consideration i f short-term tests have to become part o f a more s c i e n t i f i c toxicology. Universit~ Catholique de Louvain, Department o f Pharmaceut i c a l Sciences, Unit o f Toxicological and Cancerological Biochemistry, UCL 73 69, Avenue Mounier 73, B1200 Brussels Belgium.

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Oral Presentations

OP 01.01

OP 01.02

C L I N I C A L E V A L U A T I O N OF C A R D I A C O U T P U T M E A S U R E M E N T BY T H O R A C I C E L E C T R I C A L BIOIMPEDANCE G. Castor. J. Motsch. P. Altmaver, J. Helms, G. Molter, I. N i e d e r m a r k Thoracic electrical bioimpedance (TEB) is a noninvasive method for continuous determination of left ventricular stroke volume and cardiac output (CO). It is generally accepted as a precise trend monitoring, but the accuracy of the measured absolute values is still a matter of debate. Therefore, the accuracy and reproducibility of TEB CO-measurement by a computerized system ( N C C O M 3 - R 7 Cardiovascular monitor, Bomed, Ltd, Irvine, CA) was compared with standard thermodilution (TD) C O - m e a s u r e m e n t (Cardiac output computer 9520A C O - E d w a r d s , Santa Ana, CA) under various conditions. In total the determined data of 1966 CO-measurements were compared and statistically analysed using Pearman-correlation Test. The overall correlation was r = 0,9474 (n = 1966) with a slope of 0,89 and'an intercept of 0,33 l/rain. PEEP during low f r e quency ventilation resulted in high intrathoracic pressure with a c o n c o m i t a n t higher intrathoracic air volume and a reduced blood volume, which did not influence determir~_tion of CO (r = 0,912, n = 155 vs r = 0,926, n = 155 during Z E E P ventilation). Measurement of CO in apnoe did not correlate (r = 0,77,n = 265) as good as measurement during the first third of inspiration cycle under mechanical positive pressure ventilation (r = 0,836, n = 260). Only a poor correlation was found (r = 0,56, n = 142) in hyperdynamic septic state patients ventilated with PEEP, whereas a correlation of r = 0,70 (n = 257) was calculated in septic patients ventilated with ZEEP. This might be due to an overestimation in hyperdynamic state by TD. The results demonstrate that TEB is a reliable noninvasive method for measuring absolute levels of b e a t - t o beat stroke volumes and CO in humans. It might become a valuable tool for investigation of pharmacodynamic effects of cardiac active drugs and for evaluation of cardiovascular-side effects of new pharmaceutics. Department of Anaesthasiology, University of Saarland, D-6650 Homburg-Saar, F R G

A MICROCOMPUTERIZED SYSTEM FOR EVALUATING THE COGNITIVE ACTIONS OF DRUGS IN THE YOUNG, ELDERLY AND DEMENTED. K.A. Wesnes, P.M. Simpson & L.C. Christmas Traditional techniques for assessing the eognitive effects of drugs have not been able to meet the demands placed upon them by recent drug development. This Is strikingly evident in the development of cognitive enhaneers to treat age-associated cognitive impairment. In Phase I work, there has been not only an absence of human models to evaluate these compounds, but also few tests sensitive enough to detect improvements in cognitive performance. In patient studies, tests designed to identify the presence of dementia have frequently been used to detect changes in cognitive efficiency produced by these compounds. However, as these tests were not designed for repeated use, their sensitivity for this purpose is extremely limited. The Cognitive Drug Research Computerized Assessment System has been developed to remedy these various shortcomings. The tests incorporated in the System have all previously proven sensitive to drug improvements as well as impairments. In young people this System is used with a scopolamine model of dementia to assess the ability of novel compounds to antagonize this cholinergically-based impairment in cognition. Parallel versions of these tests have been specifically developed for use in trials to assess the ability of compounds to improve cognition in Age-Associated Memory Impaired patients, and either to arrest or reduce the decline in cognition of demented patients. This paper will describe (a) the use of this System in a scopolamine model and its sensitivity to cognitive enhancers, (b) a parallel version of the System for use with elderly non-demented patients and its drug sensitivity, and (c) the validity and test-retest reliability of a version for demented patients and its ongoing use in English and European Multi-Centre trials. Cognitive Drug Research, 13 The Grove, Reading RGI4RB UK

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OP 01.03

OP 01.05

T ~ 30 MI~DTE UREAm3C BROTH TESt IS NONINVASIVE, RAPID A ~ E C G N ~ CAL FOR TH~APEUTIC MC~rfrOPdNG OF ~ c r ~ P?L~Y (CP) INFECTIC~S R.H. Eqqers, F.E. L6dtke, R. Teqeler, G. Lepsien, and F.E. Bauer. Cp, an urease ~esitive hecteri~, is related to gastrednodenal lesions and to high relapae rates of duodenal ulcers in man. In a preliminary study Graham et al. (Lancet 1987 I, 1174) propesed a 3 hours breath test using 350 mg tSC-ures. In the present study this test was further developed. Methods: Fifty four patients with different endescopically dco~mented gastrednodenal lesions received 200 ml 0.i N citric acid and 75 ,g tsC-urea p.o. Ten of the participants were tested several times with different doses (350, 150, 75 rag). Three Cp positive patients with a four weeks treatment with colloidal bismuth subsalicylate (CBS) 1.8 g/day combined with amoxycillin 2.25 g/day starting at day 15 were monitored 3 times/week by the urea breath test. Breath samples were collected before and after applicatien of urea at I0 rain intervals for 60 rain and measured by stable isotope ratio mass spectrometry. Resttlts: IsC02 exhalation was expressed as _%dose per mmol _CC= produced per kg _body weight (%D/CBW). Citric acid used as test meal had no effect en *sC0z/t20~ ratios. The results were independent of the dose of teen, 75 m~ being optimal. Forty Patients (74%) were Cp positive as measured by culture, microscopy, end teeese test. Within 30 rain these Cp pemitive patients developed tsCfh exhalation rates of 0.44-5.63 %D/CBW in contrast to Cp negative Patients with <0.044 %D/CBW (p<0.00001). The sensitivity of the IsC0z urea breath test was 98%, specificity 93%. Mcmitoring of CBS monotherapy revealed a fall of %D/CBW of approx. 60~ within day 1-3 with no further reduction. Ccabinati~ of CBS pies amc0~cillin further reduced %D/CBW to values obtained in Cp negative subjects within day 16-19. Conclusion: The optimised *3C-urea breath test using the 30 ,tine ~ a t i o n rate is not only highly sensitive, specific, and less expensive than endoscopy, but also noninvesive. It appears to be ideally suited as endpoint in therapeutic trials. Preliminary results show an immediate therapeutic efficiency of CBS and a oonversion to Op negative values after combination with amoxycillin. Dept. of Clinical Pharmacology, Genrg-August-University, Robert-KochStr. 40, D3400 Goettingen, FRG.

AUTOMATED QUANTITATION OF PSORIATIC LESIONS THROUGH TRUE COLOR IMAGE PROCESSING M. Herbin, A. Venot, L. Dubertret, J.Y. Devaux, G. Strauch, and G. Feutren During clinical trials the severity of psoriatic lesions is usually quantified by the PASI score (Psoriasis Area and Severity Index). This score takes into account the erythema, scaling and infiltration severity and the surface of the lesion. These parameters are subjectively evaluated by Dermatologists using rough grading scales. We proved that the PASI coefficient of variation could be greater than 50~ so that we attempted to develop an automated score (AS) which is presented and evaluated in this work. During the clinical trial of ciclosporin in severe psoriatic forms 128 color digitized images (ROB system) were acquired from patient color slides taken in standardized conditions. These images were registered using an automated procedure based on a complex registration model (translation, rotation, magnification, and linear transformation of pixel values). An automated segmentation was carried out on each image in order to separate the healthy skin from the erythema and sealing regions. 52 image couples were first selected for building a new score based on erythema (redness quantitated from ROB pixel values), sealing (whiteness derived from saturation evaluation) and lesion surface. This score was validated using a second independent sample of 48 "image couples. AS and PASI respectively agreed in 7 1 % and 65 of cases with expert advices given in simple terms of improvement and aggravation.

OP 01.04

OP 02.01

PHARMACODYNAMIC EFFECT OF SHORT-ACTING NITROGLYCERIN: NON-INVASIVE EVALUATION BY A NEW SELF-MONITORING DEVICE

ANTIPYRINE AND INDOCYANINGREENCLEARANCE IN PATIENTS BEFORE AND AFTER LIVER RESECTION H. Heidemann, K. Hoffmann, R. Engemann* I . Medizinische und C h i r u r g . * - K l i n i k , C h r i s t i a n - A l b r e c h t s U n i v e r s i t ~ t K i e l , FRG

E. A. Sotaniemi and J. T. Lahtela Oral nitroglycerin (N) has been used as anti-anginal agent for more than 100 years. The onset of action of N is rapid (1-2 min) and dependent on the absorption of the parent drug into the circulation. The anti-anginal potency of N compounds varies greatly and correlates poorly with the drug/metabolite plasma concentrations

(CPT 42: 273-277, 1987). There are methodological difficulties to measure th e response t o N t a b l e t s due to rapid onset o f a c t i o n . We evaluated the problem by measuring n o n - i n v a s i v e l y the pharmacodynamic e f f e c t o f two N t a b l e t s ( N i t r o R~ Orion, Finland and Nitromax R, Dumex, Danmark) by using a new self-monitoring~ computeruized device (Sport Tester PE 3000, Polar Electro, Kempele, Finland). Heart rate after sublinqual placebo~ Nitro and Nitromax was recorded in 10 healthy subjects and 10 patients with ischemie heart disease. The onset of action began after I min and reached its maximum within 3 min (volunteers) and 3.5 min (patients). Maximal increase was higher after Nitromax than Nitro. Subjects on betablockers has a smaller increase in heart rate than other patients or volunteers. In both groups placebo had no significant effect on heart rate. In vitro disintergartion time was more rapid with Nitromax (<14.1+2.2 s) as compared to Nitro (79.1+26.7 s, p < 0.002). The hardness of the tablets was equal. The onset and potency of action of N compounds seems to be related to the dissolving properties of the tablets. The microcomputer technology offers a reliable and non-invasive method to record

d i f f e r e n c e s between the onset o f a c t i o n o f s h o r t - a c t i n g N compounds. C l i n i c a l Research Unit. Department o f I n t e r n a l Medicine, U n i v e r s i t y o f Oulu and Deaconess H o s p i t a l , SF-90220 Oulu Finland

These results lead us to propose image processing as a new tool which permits to derive objective quantitative parameters during clinical trials in dermatology. IRT-ECLIMED, H6pital Cochin, 27 rue Fg St Jacques, 75674 PARIS Cedex 14, Inserm U312, Cr@teil and Laboratoires Sandoz, FRANCE.

Expanded lobectomies of the l i v e r are possible in cases of malignant tumors or s o l i t a r y metastases. I t was the purpose of t h i s study t o i n v e s t i g a t e regeneration phenomena of the l i v e r before and up to 6 month a f t e r the surgical i n t e r v e n t i o n . We measured the a n t i p y r i n e clearance (AP) as a parameter o f the cytochrom P450 system and the indocyaningreen clearance (ICG) as a parameter o f an a c t i v e b i l i a r y t r a n s p o r t system. A t o t a l of 9 p a t i e n t s (6 females, 3 males; median age 58 years) was studied. AP was measured by HPLC, ICG by photometer.

Anti pyri ne Cl(ml/min) Before After: 1 week 4 weeks 12 weeks 24 weeks

t I/2(h)

Indocyaningreen VD(1) Cl(ml/min) tl/2[min)

VD(I)

55.1-+24.8 10.3+- 4.3

41+-10 561+162

3.9+_I.2

3.1+-0.7

27.2t-I0.6" 26.~II.5 30.~13.2 29.~I0.6

4~ 3~ 3~ 3~

3.1+1.5 5.~I.9 3.5+--0.6 2.~0.6

2.4+_0.9 2.6+_0.6 3.0+I .6 2.0-+0.6

19.4+ 7.5 19.3-+13.3 14.7+-4.0 15.~ 4.1

8 488+-204 6 9519~187 8 462+ 81 6 458~_130

Conclusion: The a n t i p y r i n e clearance however not the indocyaningreen clearance is a useful parameter to judge l i v e r f u n c t i o n a f t e r surgical r e s e c t i o n . Regeneration phenomena do not take place over time. A dose reduction seems necessary f o r drugs t h a t are metabolized by the cytochrom P450 system of the l i v e r .

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OP 02.02

OP 02.04

EFFECT OF C Y S T A T H I O N I N E , A PHYSIOLOGICAL PRODRUG OF CYSTEINE, ON A C E T A M I N O P H E N INDUCED LIVER INJURY. T. Itoh, Y. Kitamura and Y. Kamisaki Department of Clinical Pharmacology, Tottori University School of Medicine, Yonago 683, Japan The h e p a t o p r o t e c t i v e e f f e c t of c y s t a t h i o n i n e as a physiological precursor of c y s t e i n e was examined in rodents. Liver injury was induced by the intraperitoneal (i.p.) injection of acetaminophen (5.0 mmol/kg). The mortality rates, serum alanine and aspartate aminotransferase activities and the histological analysis of the livers, which were obtained from alive mice, were adopted as markers of liver damages. Two administrations of cystathionine (5.0 mmol/kg, i.p.), one at 20 min before and one after the injection of acetaminophen, completely protected the liver against the acetaminophen-induced injury. Cystathionine prevented the acetaminophen-induced liver injury, restoring the glutathione level in the liver. Co-administration of taurine (5.0 mmol/kg) increased the hepatoprotective activities of cystathionine even at lower doses of cystathionine (0.18 and 0.55 mmol/kg). Propargylglycine, an inhibitor of cystathionase, abolished the hepatoprotective effects of cystathionine, although it could not interrupt the effect of cysteine. When cystathionine with or without taurine was administered i.p, into rats, the elimination kinetics of cystathionine from rat serum showed good fit to a one compartment model. Subsequent to the decrease of serum cystathionine, the concentration of c y s t e i n e was i n c r e a s e d , Coadministration of taurine did not change the half-life of cystathionine, but significantly increased the half-life of cysteine. This effect of taurine was also observed when cysteine was administered i.p. into rats. In conclusion, cystathionine had a hepatoprotective e f f e c t against acetaminophen-induced liver injury as a physiological prodrug of cysteine, and taurine potentiated the hepatoprotective effect of cystathionine,

GAGTROPROTECTIVE EFFECTS OF MILK PHOSPHOLIPID$, TOTAL L I PIDS AND BUTTER SERUM ON ETHANOL-INDUCED ULCER IN THE RAT A. P a r v i a i n e n , S. Salminen, D. Homer, H. Vapaatalo, Department o f Biomedical Sciences, U n i v e r s i t y o f Tampere, 83520 Tampere, V a l i o F i n n i s h C o - o p e r a t i v e D a i r i e ~ Assoc i a t i o n R. & D. Centre, 00180 H e l s i n k i , F i n l a n d .

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AIRINIST~TION QF ~ C ACID (ImCA) IN PAT]~RTS ~ BILTARY ~ (PBC) D(ES ~ ~ ~AIDCEJhtL%R F[RCTI(N E. Lotterer z , A. Stiehl2 , U. Foelsch 3 and J. Bircher I High ooncebtration.s of endogenous bile acids (HA) within hepatocytes in experimental cholestasis may disturb cellular function and thereby be toxic. In such situations administration of UDCA was found to be protective to hepatocytes (Kitani et el, Life Sci 30, 515, 1982). Consequently, euric/ment of the BA pool with UDCA may be therapeutically useful in PBC (Poupen et al., Lancet i, 834, 1987). In this disease, however, the consegnences of treatment With UDCA for hepatocyte function are as yet insufficiently known. Methods: Nine patients With PBC were treated with UDCA 15 mg/kg/day. Diagnoses were based on typical elinical and laboratory findings and on compatible histology. The gnlactose elimination capacity (GEC; Tygstrup, Scand J Clin Lab Invest 18, 118, 1966) and the aminopyrine breath test (ABT; Miotti, Digestion 39, 241, 1988) were applied as measures of the metabolic capacity of hepatocytes before and after 6 months of UDCA. Total bile acids were determined enzymatically, and individual bile acids by GLC. Results: Pruritus improved in all affected patients and no adverse drug reactions were recorded. Alkaline phes-phatase fell from 458 + SD: 157 to 260 + 100 U/1, r-glutamyl transferase from 223 • 173 to 77 • 74 U/I andG~T from 39-+ 17 to 24 • ii U/I (all p < 0.01). The GEC (4.7 + 1.4 versus 4.6 + 1.7 mg/min/kg, n.s.) and the ABT (0.60 + 0.33 versus 0.65 • 0.34 %, n.s.) remained unchanged after the 6 month period. Depending on the stage of the disease total plasma BA cononntration~s increased significantly, whereas endogenous BA (= total minus UDCA) were decreased in stages I -III and unchanged in stage IV. Coaclusions: The results confirm beneficial effects of UDCA on pruritus and biochemical abnormalities, whereas cellular function as expressed by GEC and ABT regained unchanged. The decrease of endogenous BA may be therapeutically useful, whereas increases in total BA-concentration in stage IV suggests caution as it may potentially be deleteri(xts. Divisions of Clinical Pharmacology I , and Gastroenterology and ~docrinology a , University of Gonttingen, Robert-Koch-Str. 40, D-3400 Goettingen and Division of Gastroenterology 2 , University of Heidelberg, Bergheimer Str. 58, D-6900 Heidelberg

SIMULTANEOUSBUFFERANDACIDCAPACITYDETERMINATIONSIN GASTRICJUICEWITH NILEPROST, A CYTOPROTECTIVEPROSTAGLANDIH Fuhrmei~ter. A. and Seifert. W. Up to now, plausible physiological medels for the concept of "cytoprotection" in pharmacology and pathophysiologyof the gastrointestinal tract have not been available. One concept of protecting the gastric mucosa is the increased buffer capacity (BC) of the surface epithelium. The current clinico-pharmacological methods are usually limited to confirming parameters classified by acidity or by buffer. This is why a method for the simultaneousdetermination of gastric acid and gastric buffer secretion has been developed. Under the exclusion of CO 2, the spontaneously outflowing gastric fluid was automaticallyset to pB 11 with HaOB.The influence of alkaline saliva was minimized by contieous aspiration. The subsequent extragastral backtitration with 1/10 n NCl leads to a titration curve with two turning points representing the equivalence points of the buffer components. The buffer concentration is found with the following fomula:

G a s t r i c u l c e r induced by a b s o l u t e ethanol was used t o examine the a b i l i t y o f m i l k p h o s p h o l i p i d s , b u t t e r serum and b u t t e r serum l i p i d s t o prevent u l c e r f o r m a t i o n . T h e i r o r a l doses ranged from 10 t o 4400 ~g P/kg c a l c u l a t e d as i n o r g a n i c phophorus. PGE2 (10-100 ~g/kg) and c i m e t i d i n e (50 mg/kg) were used as r e f e r e n c e compounds and 0.9% NaCl served as c o n t r o l . F o r t y - f i v e min a f t e r the a d m i n i s t r a t i o n o f the p r e p a r a t i ~ ons or the drugs the r a t s were given a b s o l u t e ethanol and were k i l l e d 60 min a f t e r t h a t . The stomachs were removed and the i n j u r i e s were analysed using a computerized p l a n i m e t r i c system c a l c u l a t i n g the r a t i o s between the l e s i o n areas and t o t a l stomach a r e a . The p h o s p h o l i p i d s and t o t a l l i p i d s in doses o f 1600 pg P/kg and 4400 ~g P/kg and PGE2 in a dose o f 100 ~g/kg were c l e a r l y g a s t r o p r o t e c t i v e a g a i n s t e t h a n o l - i n d u c e d u l c e r (p
BC[mmol] =

(mlHCl2,~q~i,al:-rnlHCll,F~a~~176 mIs.apl,

The validation of the methodwith weighed quantities of NaHC03between0.I and 1.0 mml showed a coefficient of correlation of 0.99 (p:
COR~I~kTION BICARBONATE ~COV]~RY

12

o,.,

11. 1.0, 9 , 8 , ,7 . ,6 , ,6 , 4 . ,6 , 2 1 ) } [

t/

......

~1.4 l.a

~ .... I

If,

1

O.91 0.8

I I

'

I

.S 0.7

b u l f e r capacity: 1~ 20.49 mraoL/l 2:18.08 mmoUI m~oVI

= 0.6

0.5 0.4

9

~o.a ~0.2 B 0,1

I

O.2

0,4

0.6

O.e

1

1.2

1.4

1.6

I I

HCl n/lO (m])

introduced Bic~bonBte (retool)

Fla. 1 , Correlation between introduced Fla. 2. Titration curve of 1 ml of HCOU-and recovered buffer capacity; aIEalizedgastric juice by UCI n/1D conn=67. taining variable amountsof buffer. Dep. Humanpharmekologie I, Schering AG, MiUlerstr. 171, D-IO00Berlin 65

A 41

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INFLUENCE OF A NEW PGE2-DERIVATIVEON THE PEPTONEAND FOOD-STIMULATEDGASTRINSECRETIONOF THE

DIFFERENTIAL SENSITIVITY OF P450dbI SUBSTRATES TO INHIBITION BY Q U I N I D I N E IN MAN. J. Turgeon. C. Funck-Brentano, H. Pavlou, R.L. Woosley and D.M. Roden. Encainide (E) is O-dealkylated to O-desmethyl encainide (ODE) which is further metabolized to 3-methoxy O-desmethyl encainide (MODE). Both these steps cosegregate with the geneticallydetermined polymorphic metabolism of debrisoquine. Since quinidine (Q) has been shown to be a potent and selective inhibitor of cytochrome P450dbl, the isozyme responsible for this polymorphism, we have evaluated the pharmacokinetic consequences of combining E+Q. Seven extensive metabolizers (EMs) and 4 poor metabolizers (PMs) received E (60mg orally + 4.5mg 14C-E i.v. simultaneously) alone and again during low dose Q (50mg q6h x 2d) in random order. Q did not alter E disposition in PMs. In EMs, Q significantly (p<0.05) decreased E systemic clearance from 935+541 (+SD) ml/min to 190• ml/min, a value not significantly different of that in PMs (126• ml/min). However, the partial metabolic clearance to ODE+MODE (635+489 ml/min) was decreased >10-fold (48• ml/min; p<0.05) by Q in EMs but was still ~10 times higher than that in PMs (6.4• ml/min; p<0.05). Low doses of Q (60mg q8h x 4d) were also administered to 3 EMs receiving chronic E therapy (50-75 mg/d). During E+Q in these patients, the areas under the plasma concentration-time curves for E and ODE were increased ~10- and ~2-fold respectively. As in the single dose study, no MODE was detectable in plasma. These data indicate that the O-dealkylation of E was partially inhibited by low dose Q while the metabolism of ODE to MODE was virtually completely inhibited. These results suggest differential sensitivity of P4500b1 substrates to inhibition by quinidine. The clinical consequences of this interaction requires further evaluation in patients. Departments of Medicine and Pharmacology, Vanderbilt University, Nashville, TN; and Department of Pharmacology, Georgetown University, Washington, DC, USA.

STOMACH

M. Mshler. W. Seifert and A. Fuhrmeister E2-type prostaglandinsinfluence gastric hormonesand acid secretion. The secretory stimulationby a protein meal is largely due to the antral gastrin release. NOCLOPROST ( N C L ) - a new PGE2-derivative - was investigatedin three studies for ant• effectsand espeeiallywith regard to a possibleinhibition of the stimulated gastrin release. 1st study: NCL as clathrate lyopkilisate was administeredto 80 healthymale volunteers in ascendingdose stages (n=4) in a dose range from 0.1lagto 500 ~g intragastral. Gastrin was stimulated after i h by peptone (200 ml of a 20% peptone solution) and after a further 3 h by a standard meal and determined for 9 h withgastrin-RIA.Results: NCL inhibits the peptone-stimulatedgastrin secretion already from 10 lag,but not the gastrin secretion after a standard meal. 2nd study: 6 voluteersreceived 250 lag NCL and 250 lag NCL clathrate solution. Gastrinwas stimulated as in stndy1 and determined at hourly intervals. In addition, the pH-valueswere measuredby intragastral glasselectrode. Results: the release of gastrin was reduced by NCL by max. 70%; the intragastral acid concentrationfell by 90% in comparisonto the pretreatment value. The two galenical formswere equivalent. 3rd study: 24 volunteersin 4 groups (n =6) received 50pgor 250 ~tgor 200 lag MISOPROSTOL 3 x dally for a period of 14 days. Gastrin was determined on 3 days (day 0, 5,12) in the 22-h profile.The intragastral pH-valueswere measuredat the same time. Results:The effect of NCL consistsprincipallyin the inhibitionof the peptone-stimuiatedgastrin release (4 h p. appl.). The effect is already clearly apparent after 50lagNCL and cannot be increased much further by raisingthe dosage.In contrast, after misoprostol,there is a sfightrise in the gastrinrelease. NCL reduced the number of pH-value < 2.5 measuredin the 12h period after peptone. A similar pH-reduction occurred under MISOPROSTOL. Conclusions:The ant• effect of NOCLOPROST is predominantly based on an inhibitionof the peptone-stimulatedgastrinrelease and on the acid secretion dependent on it, this already occurringat a dose of lqag/man. There is but tittle influenceon the release of gastrin throughthe regular ingestion of food. NOCLOPROSTthereforeprovidesrefiable protectionfrom inadequate acid stimulus. HumanpharmakologleI, ScheringAG, Miillerstr. 171, D-1000Berlin 65

OP 03.01 PRENYLAMINE ENANTIOMERCONCENTRATIONSAFTER SINGLE AND MULTIPLE DOSAGEIN MAN H. Spahn, Y. Gietl, H. Knauf(1) and E. Mutschler The two enantiomers of prenylamine (PA), a c h i r a l WHO-class V calcium antagonist, are known to have d i f f e r e n t pharmacological e f f e c t s with S-(+)-PA being a p o s i t i v e i n o t r o p i c and R-(-)-PA a negative i n o t r o p i c agent. Using reversed-phase HPLC (ODS, methanol/disodiumhydrogen phosphate s o l u t i o n ) a f t e r formation of the d i a s t e reomeric d e r i v a t i v e s with S-(+)-naphthylethyl isocyahate as c h i r a l d e r i v a t i z i n g agent, the pharmacokinetics of S- and R-PA was studied in eight healthy volunteers. They received a single 200 mg p.o. dose of racemic drug on day I, I00 mg b . i . d , f o r 9 days and another 200 mg dose on day I I . D i s t i n c t differences were found between the enantiomers. Plasma h a l f - l i v e s of S-PA were generally higher than those of R-PA. Average maximum plasma concentrations as well as AUC values of the R-enantiomer exceeded those of the S-form 5 times [Cmax(day I ) , 9.2 + 4.2 f o r S-PA and 50.7 + 20.6 ng/ml f o r R-P~; AUC(day- l ) , 164 + 71 f o r S-PA and 701 + 225 ng ml- h f o r R-PAl. UnboUnd f r a c t i o n s in plasma~as determined by u l t r a c e n t r i f u g a t i o n , were higher f o r S-PA. Only traces o f unchanged PA were excreted i n t o urine: 0.012 % S-PA and 0.014 % R-PA a f t e r a single 200 mg p.o. dose. The average renal clearance was 3 times higher f o r S- (4.0 + 5.2 ml/min a f t e r single dose) than f o r R-PA (1.3 + 1.4 ml/min). Upon acid-hydrolysis of urine samples -more S-prenylamine was formed, i n d i c a t i n g a s t e r e o s e l e c t i v e conjugation. Pharmakologisches I n s t i t u t f u r Naturwissenschaftler, Johann Wolfgang Goethe-Universit~t, Theodor-Stern-Kai 7, Geb. 75 A, D-600O Frankfurt/M. 70 and (1) St.-Bernward-Krankenhaus, TreibestraBe 9, D-3200 Hildesheim, F.R.G.

OP 03.03 STEREOSELECTIVE STUDIES ON P-450 HUMAN-2 (MEPHENYTOIN HYDROXYLASE) EXPRESSED IN YEAST CELLS A N D H U M A N LIVER. R. Kato, T. Yasumori and Y. Yamazoe Previously we have purified P-450 human-2 (mephenytoin hydroxylase) from human liver, isolated a cDNA clone and determined the cDNA sequence (J. Biochem., 102, 1075-1082, 1987). Moreover, we have demonstrated the expression of P-450 human-2 in yeast cells using a galactose-inducible expression system (Mol. Pharmacol., in press). The expressed P-450 human-2 in yeast cells showed high affinity for benzo(a)pyrene hydroxylation and S-mephenytoin 4-hydroxylation as that purified from human liver and showed 56K band by immunoblot analysis on SDS-PAGE. Both activities are strongly blocked by anti-P-450 human-2 IgG. The content of immunochemically determined P-450 human-2 content in human livers was correlated with the activity of Smephenytoin 4-hydroxylase, but not with S-mephenytoin N-demethylase. According to R/S ratio in mephenytoin 4hydroxylase in 19 human liver samples, the number of extensive metabolizer was 14 and poo r metabolizer was 5. The R/S ratio of the liver sample, from which P450 human-2 was isolated, was 0.193 (extensive metabolizer) and that of the expressed P-450 human-2 in yeast cells was about 0.2. These results indicates that P-450 human-2 is constitutively expressed as a major cytochrome P-450 for S-mephenytoin 4-hydroxylase and the P-450 expressed in yeast cells is real P-450 human-2 which is isolated from the extensive metabolizer. Department of Pharmacology, School of Medicine Keio University, Shinjuku, Shinanomachi 35 Tokyo, 160 Japan

A 42

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DOES RESTRICTION OF CAFFEINE INTAKE AFFECT MIXED FUNCTION OXIDASE ACTIVITY AND CAFFEINE METABOLISM M. Levy~ Y. Caraco and E. Z y l b e r - K a t z C a f f e i n e e l i m i n a t i o n k i n e t i c s were s t u d i e d in 11 h e a l t h y s u b j e c t s b e f o r e and f o l l o w i n g a r e s t r i c t i o n o f c a f f e i n e c o n t a i n i n g p r o d u c t s f o r a mean p e r i o d o f 25 d a y s . In 7 s u b j e c t s d e c r e a s e d c a f f e i n e m e t a b o l i s m was n o t e d . Alt o g e t h e r t h e mean d e c r e a s e o f t h e e l i m i n a t i o n c o n s t a n t ( k e l ) was 17% (0.0243) (p = 0 . 0 5 ) . This c h a n g e was more pronounced i n s u b j e c t s who i n i t i a l l y exhibited rapid caffeine clearance. At t h e same t i m e no c o n s i s t e n t e f f e c t could be o b s e r v e d on t h e h e p a t i c mined f u n c t i o n o x i d a s e (MFO) system activity as reflected by the 6~)-hydroxycortisol/17 hydroxycorticosteroid ratio or gamma-GTP blood levels. Ten of the subjects reported a decreased caffeine consumption following the restriction period. There was no concordance between ~ kel and the change in 6 (O)-OHF/17OHCS ratio or the change in habitual caffeine consumption. The individual variation in the effects of caffeine on the MFO and possibly on other target organs awaits further elucidation. Clinical Pharmacology Unit, Department of Medicine A Hadassah University Hospital, Jerusalem 91-120 Israel

PATHWAY-SELECTIVE SEX DIFFERENCES IN THE METABOLIC CLEARANCE OF PROPRANOLOL IN MAN. T. Walle, T.D. Cowart, U.K. Walle and E.C. Conradi. In a retrospective population study (Clin. Pharmacol. Ther. 38:509-518, 1985) i t was suggested that the clearance of propranolol was higher in men than in women, an observation that was novel for B-blocking drugs. In the present prospective study we examined this question in more d e t a i l , determining the clearance of propranolol through each of i t s three primary metabolic pathways in 9 young women and 15 age-matched men. No participants in the study were smokers or taking other drugs. Their diets were identical and the study was performed in a c l i n i c a l research f a c i l i ty. The propranolol doses consisted of a single 80 mg oral dose given simultaneously with a 0.I mg/kg i . v . dose of hexadeuterium-labeled drug. Plasma concentrations of the two propranolol forms were determined by GC/MS and the urinary excretion of metabolites by HPLC and GC/MS. The oral clearance of propranolol was s i g n i f i c a n t l y higher (67%, p
OP 03.05

OP 04.01

PHENPRoCOUMONKINETICS AND OXIDATIVE LIVER METABOLISM WITH AND WITHOUT PROBENECID A. Bammel, H. Mbnig, K.H.Zurborn, E.E.Ohnhaus, W. Kirch In a previous study i t could be demonstrated that the elimination of phenprocoumon (PPC) is accelerated by simultaneous administration of probenecid. The present study was therefore carried out in order to determine whether the observed shortening of elimination h a l f - l i f e might be due to an induction of the microsomal drug-metabol i z i n g enzyme system and/or to a diminished enterohepatic c i r c u l a t i o n of phenprocoumon. Probenecid-induced changes in the pharmacokinetics of phenprocoumon f o l lowing a single oral or intravenous dose (0.22 mg/kg b.w.) were investigated in 14 healthy volunteers. The urinary elimination of phenprocoumon and i t s glucuronide was reduced by more than 70 % (p<0.05). In contrast, the terminal h a l f - l i f e decreased by about 35 % (p<0.05). Peak concentrations after oral and intravenous administration were not diminished after coadministration of probenecid. As there were no s t a t i s t i c a l l y s i g n i f i c a n t differences between oral and intravenous administration, an impaired absorption and subsequently diminished enterohepatic c i r c u l a t i o n of PPC could be excluded. On the other hand after 7 days of probenecid-therapy there were s i g n i f i c a n t increases in antipyrine clearance of about 30 % (p<0.05) and in urinary excretion of 6Bhydroxycortisol by about 40 % (p
MODEL-INDEPENDENT KINETIC PARAMETERSOF METHYLPREDNISOLONE IN CHILDREN RECEIVING HIGH DOSE PULSE THERAPY S.Ito , H.Yoshioka ~ T.Oka and Y.Kusunoki The short-term parenteral use of methylprednisolone (MP) in high doses (MP pulse therapy) has been recommended for a v a r i e t y of diseases in children. However, associated l i v e r dysfunction and/or hypoalbuminemia may a l t e r the disposition of MP, and necessitate dose adjustment. In the present study, we chracterized kinetics of MP at high doses in children with either nephrotic syndrome (group A,n=6) or various non-renal diseases,which may p o t e n t i a l l y involve l i v e r (group B,n=9). The average values of model-independent parameters were s i m i l a r in the two groups(Table). Three patients exhibited apparent nonl i n e a r kinetics:one in the group A, two in the group B. The two patients had abnormal l i v e r function test values. These children showed two to three times greater dosenormalized AUCs than those with linear kinetics. Our results suggest that hypoalbuminemia per se does not a l t e r MP disposition at high-doses, and that more attention should be given to elucidate non-linear kinetics in terms of therapeutic and untoward effects of MP pulse therapy especially in children with diseases involving liver.

I. Medizinische K l i n i k , Christian-Albrechts-Universit~t, SchittenhelmstraBe 12, 2300 Kiel I, FRG

Table. Patients' data and model-independent parameters Group N Age (yr) A 6 9.3• B 9 8.4•

Weight (kg) 3113• 26.8•

Dose (mg/kg) 26.3• 26.2•

Albumin,serum (g/dl) 2.8• 3.5•

C1 Cl-u MRT Vdss AUC/Dose (llkg/h) (ml/kg/h) (hr) (I/kg) (kg.h/l) A 0.63• 37.1• 3.4• 2.0• 2.06• B 0.44• 27.4• 3.0• 1.3• 2.61• Mean• clearance;MRT,mean residence time; Vdss,velume of d i s t r i b u t i o n at steady state Department of Pediatrics, Asahikawa Medical College, Nishikagura 4-5-3-11, Asahikawa 078, JAPAN

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PHARMACOKINETICS OF CYCLOSPORIN IN VERY YOUNG CHILDREN STUDIED IN PREPARATION FOR RENAL TRANSPLANTATION. K.Hoppu, O.Koskimies, C.Holmberg and E.L.Hirvisalo.

PHARM~COKINETICS OF VIGABATRIN (GVG) IN CHILDREN WITH MEASUREMENT OF R(-) AND S(+) ENRNTIOMERS. G. OLIVE (I), E. REY (i), G. PONS (i), M.O.RICHI%RD (i), F.VAUZELLE (i), O.DULAC (2), P.d'RTHIS (i). (1)Dept.Clin.Pharmacol. (2)Neuropediatrie-Hop.St Vincent de Paul-Paris-France. G V G a specific irreversible inhibitor of GABA transaminase,is a new antlepileptic drug (phase III clinical study). Two groups of 6 epileptic children (I:lmonth-2y.o.;II:2-15y.o.) with u n c o n t r o l l e d seizures received a single 50 mg/kg oral dose. Blood samples (500ul) were collected at 0.5,1,2,3,6,9,12 and 24h after administration. The enantiomers R(-) and S(+) were determined by GC-MS. Cmax(mg/l) Cl(i/h/kg) Vd(i/kg) tl/2(h) I II I II I II I II R(-) 20.6 34.7 0.498 0.355 2.01 2.77 2.87 5.69 SD 5.7 12.1 0.110 0.083 0.68 1.19 1.03 2.86 S(+) 13.8 19.4 0.591 0.446 4.63 3.48 5.65 5.47 SD 4.5 6.9 0.165 0.103 1.12 1.23 1.52 1.93 Significant differences were observed b e t w e e n enantlomers on Cmax (S(+)R(-); p<0.01) in both groups and on tl/2 (S(+)>R(-); p<0.01) and Vd (S(+)>R(-); p<0.001) in group I. The R(-) tl/2 was linearly correlated to age (r=0.82; p<0.01). Significant differences were observed between groups : R(-) %1/2 was shorter and apparent plasma clearance larger in group I than in group II. The absence of significant difference in the GVG kinetic parameters between the two groups for the b i o l o g i c a l l y active enantiomer S(+) implies a similar dose regimen recommendation in 1 month to 15y.o.children.

Rapid elimination of cyclosporin has been previously described in children following renal transplantation, but the age groups studied have not been adequately defined. We studied 7 children (mean age: 2.07yrs; range 1.592.53) with congenital nephrosis of the Finnish type before renal transplantation to determine the appropriate individual dose. Cyclosporin (Sandimmun ~) was given as a single oral dose (10mg/kg) or as a 4-hour iv infusion (3mg/kg). Cyclosporin concentration was determined from whole blood samples taken at 0,1,2,3,4,6,9,12,16 and 24 h after the oral dose and before, in the middle of (2 h) and at the end of the iv infusion (4 h) and 0.5,1,2,3,6,9,12,16 and 24 h after it. Cyclosporin was determined with both specific and non-specific monoclonal radioimmunoassay ('Sandimmun Kit'). After the iv infusion the mean terminal tl~2 for cyclosporin was 5.1 h (range 2.8-8.8), CLo 11.6 ml/min/kg (7.1-23.5) and V 2.3 L/kg (1.3-4.6). The peak cyclosporin concentration after oral administration was attained in 1.9 h (1.03-2.03) and the mean absorption time was 3.6 h (0.8-11.6). The mean bioavailability was only 18% (range 5-33%), in two patients it was <10%. The mean ratio of non-specific to specific cyclosporin AUC was 1.4 (1.11.6) after iv and 2.1 (1.7-3.1) after oral dose (p<0.03). Fast elimination and poor bioavailability lead to high dose requirements in children of this age group. Extreme combination of both exist and cannot be predicted without pharmacokinetic studies. To attain a pre-dose blood cyclosporin level of 200-300 l.tg/L at steadystate we recommend an iv cyclosporin dose of 5 mg/kg/day; and an oral dose of 25 mg/kg/day. Due to the fast elimination rate, the daily dose should best be divided in 3 doses, A conversion of the iv dose should be made by a multiplication factor of 5. Children's Hospital, University of Helsinki, 00290 Helsinki, Finland.

OP 04.03

OP 04.05

D O S E - R E S P O N S E STUDY OF METOCLOPRRMIDE (M) IN GRSTROESOPHRGAL REFLUX (GER) IN INFANCY. G.PONS(1),J.F.DUHRMEL(2),M.GUILLOT(3),J.B.GOUYON(

RANDOMIZED, CROSS OVER COMPARISON OF IRON EXCRETION BETWEEN DESFERROXAMINE (DFO) AND THE NEW ORAL CHELATOR 1, 2 DIMETHYL-3-HYDROXYPYRID-4ONE (L1). Gideon Koren. Nancv F. Olivieri. Melvin H. Freedman. Patrick St. Louis, Richard Panicucei, Robert A. McClellan& DFO is currently the gold standard iron chelator in children with transfusional iron overload. However, the drug is neurotoxic, causing permanent hearing and visual loss in many children. Moreover, it is a very expensive drug and a nightly subcutaneous infusion costs $12,000 per patient annually. As important, toward their adolescence, children with thalassemia become noncompliant with the cumbersome and painful DFO schedule. We compared routine DFO therapy to a low dose of the new oral chelator 1, 2 dimethyl-3-hydroxypyrid-4-one (L1) synthesized in Toronto. Six thalassemics (age range 10-29) who were either neurotoxic or noncompliant with routine DFO served as their own control for the comparison. They were randomized to receive first DFO (50 mg/kg/day x 8 h for 3 days) or L1 (50 mg/kg q 8h for 3 days), one month apart at similar hemoglobin levels. Over the 3 day study and one day washout, urinary iron excretion was 98+67 mg (x~+SD) with DFO and 56-+20 mg with L1. Iron excretion was superior with L1 in 1 patient, was comparable with L1 and DFO in 2 patients, and was superior with DFO in 3 patients. In these latter patients, higher doses of L1 will be tested before instituting chronic therapy with the drug. In an additional 2 patients, iron excretion with L1 exceeded that with DFO historical control by 37% and 130%. The new oral chelator was comparable to DFO in urine excretion if Ca ++, Mg ++, Po4 -3 and Cu ++. None of the children experienced adverse effects attributed to Lt; one patient had nausea and Vomiting with both modalities. The cost of LI production was 1% that of DFO. We conclude that iron excretion with the new oral chelator L1 is comparable to DFO. Longitudinal studies are in progress to assess optimal dose and long term efficacy and safety of the drug. Division of Clinical Pharmacology, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada, M5G 1X8

4),Ph.d'ATHIS(4),M.O.RICHRRD(1),E.REY(1),C.MORAN( I),D.BOUGLE(2),E.BELLISSANT(1),Ph.EMENT(5) J.BADOUAL(1) and G.OLIVE(1). Twenty four 1 to 18 month old infants referred to 4 centers for suspected GER, whose esophagal pH was recorded over a 6-hour period following a standard formula meal at 9 to I0 a.m. (H0-day i) and fulfilling the criteria of more than 5% of time esophagal pH was <4 (HI to H6), entered double-blind p l a c e b o - c o n t r o l l e d dose-response trial of (M). 24h later the procedure was repeated after a single oral dose of (M) or placebo solution (day 2). Patients were randomly assigned to receive either placebo or 0.1,0.2,0,4 mg/kg (M), 30 min before the formula meal (n=6/group). (M) plasma concentration was m e a s u r e d lh after dosing (C lh). On day i, the time of esophagal pH<4, and 5 other parameters were not significantly different in the treatment groups. On day 2, time pH<4 (m(SD)) decreases from 33(13) to 30(33), 39(27) to 36(47), 42(15) to 18(13) and 48(25) to 31(46) min in placebo, 0.i, 0.2, 0.4mg/kg (M) groups respectively. Possibly due to the large interindlvidual variability, no significant differences in parameters were observed between the different groups, but there is a tendency for most of them to be improved in 0.2 mg/kg (M) group. None of the parameters correlates with either (M) doses or the C lb. No side effects were reported. A similar study should be performed after repeated dosing regimen. (1)Dpt Pharmacol Clln,Hop St Vincent de Paul, 74Av.Denfert Rochereau Paris 14-F. (2)CHRU Caen, (3)CHG Lisleux, (4)CHRU Dijon, (5)Lab. Delagrang e Paris - France.

A 44

OP 04.06

OP 05.02

METHIONYL GROWTH HORMONE PHARMACOKINETICS IN CHILDREN WITH IDIOPATHIC GROWTH HORMONE DEFICIENCY. G.L. Kearns, S.F. Kemp and J.P. Frindik Adult studies have reported mean elimination t89values of between 0.42 and 1.3 hr for [125I] human growth hormone (GH) and endogenous GH, respectively. Although methionyl growth hormone (hGH) has been used since 1985, little is known about its pharmacokinetics (PK) in children. We determined PK parameters for hGH in 12 children (I female; 12.4• yr; 31.2• kg; 135.8• cm) after a single SUBQ injection (Pre), and after 4 weeks (Post) of therapy. All had idiopathic GH deficiency documented by plasma GH < i0 ng/ml following standard provocative tests. Subjects received 0.3 mg/kg/week of hGH; 6 received this dose divided 3 times weekly and 6 with the dose divided into daily injections. Repeated blood samples (n=14) were obtained after dosing and hGH was quantitated by im~nunoradiometric assay. Plasma concentration vs. time data were curve fit using a WLS algorithm which enabled calculation of the following parameters: ......................................................... Tmax (hr) Cmax(ng/ml) CL(L/hr/kg) VDss(L/kg) Pre 4.5• 33.3• 0.27• 1.4• Post 3.4• 35.5• 0.46• 1.8• ......................................................... The mean apparent absorption and elimination t89for hGH was 2.0 and 4.9 hr, and 1.5 and 4.2 hr for the Pre and Post evaluations, respectively. The PK parameters were not significantly different between Pre and Post evaluations, or between patients receiving hGH daiIy or 3 times per week. A linear correlation (r=0.93; p<0.001) between hGH dose and AUC supported dose-independent kinetics. The elimination t89for hGH in our subjects was much greater than previously reported and in part, may be due to prolonged absorption of hGH following SUBQ dosing. Variations in dosing and/or multiple dosing do not appear to alter the PK of hGH in children. Divisions of Pediatric Clinical Pharmacology and Endocrinology, Arkansas Children's Hospital, Little Rock, AR 72202, USA

P R O S P E C T I V E S T U D Y OF H O S P I T A L I Z E D P A T I E N T S P R E S E N T I N G A L I V E R D I S E A S E : C O M P A R I S O N OF B I O L O G I C A L P A T T E R N S , E V O L U T I O N A N D D R U G USE A C C O R D I N G TO THE DISEASE E T I O L O G Y

J.C. PERE, G. SALAME, B. BEGAUD. F. HARAMBURU Between 1988 February 15 and October 31,340 inpatients from 12 departments of medicine presented a non-lithiasic non-tumoral hepatitis. 316 answered a questionary about personal habits (alcohol, tobacco, nu~ements) and drug consumption. This study describes the symptomatological and evolutive patterns of the different etiologies, and evaluates the influence of drug use on diagnosis and prognosis. Each patient used an average of 5,7 different drugs, the number of which varied with patients habits (alcohol, tobacco), with age and medical antecedents and with the final diagnosis. Non-narcotic analgesics and non-steroidal anti-inflammatory drugs, anxiolytics, antibiotics and multivitamins are the most used classes of drugs. AVERAGENUMBER OF DRUGS USED ACCORDINGTO AGE AND ETIOLOGY

ALCOHOLICHEPATITIS CIRRHOSIS UNDETERMINED DRUGINDUCED CHRONICHEPATITIS VIRAL HEPATITIS CARDIACLIVER GENERAL DISEASE

< 35 years

35 - 50

50 - 65

> 65

aU

2,6 6,5 6,1 6,8 7,3 4,5

2,6 3,9 4,7 t5,7 5 7

3 4,2 5,6 8,3 7 5 7 6

6 6,2 7,9 11,1 5,5 6,5 9 7,3

2,75 * 4,77 6,6 10,44" 6,36 5,53 8,38 7,1

-

8,5

5

ALL 5,2 4,4 5,1 7,8 CENTRE DE PHARMACOVIGILANCE DE BORDEAUX HOPITAL PELLEGRIN - ZONE NORD Bat 1 A 33076 BORDEAUX-CEDEX FRANCE

5,71

OP 05.01

OP 05.03

DRUG RELATED HOSPITALIZATIONS IN A MEDICAL WARD. A HIGH-INTENSITY STUDY. J. Hallas~ B. Harvald, L.F. Gram, E. Gs K. Bresen and T. Haghfelt Three-hundred and t h i r t y t h r e e consecutive p a t i e n t s in a general medical ward were evaluated in a h i g h - i n t e n s i t y m o n i t o r i n g o f drug events as cause o f h o s p i t a l i z a t i o n s . Considering the d e f i n i t e and probable drug events, we found 10.8~ (95~ confidence l i m i t s : 7.7-14.6 %) o f a l l admissions to be drug r e l a t e d h o s p i t a l i z a t i o n s (DRN). Of these, 8.1~ were adverse drug r e a c t i o n s and 2.7~ were t h e r a p e u t i c f a i l u r e s due to too low e f f e c t i v e dose. We found 2.4~ o f the admissions to be caused by e r r o r s in p r e s c r i p t i o n and a f u r t h e r 3.9~ that could probably have been avoided by an a p p r o p r i a t e e f f o r t from the h e a l t h s e r v i c e . The p a t i e n t s admitted because o f a drug event took s i g n i f i c a n t l y more drugs than o t h e r s , also when drug non-users were excluded. Other, non-significant c h a r a c t e r i s t i c s o f drug r e l a t e d h o s p i t a l i z a t i o n are o l d e r age, female sex, s h o r t e r d u r a t i o n of sSay and drug therapy e s t a b l i s h e d by h o s p i t a l d o c t o r . However, the distribution o f the a v o i d a b l e drug events compared to that o f the doctors r e s p o n s i b l e f o r the drug treatment point to the primary s e c t o r as the a p p r o p r i a t e t a r 9 e t f o r an i n t e r v e n t i o n . Judged by the sources of the i n f o r m a t i o n that ted to the suspicion o f a drug event and what was necessary f o r o full evaluation, a good estimate o f a DRH-rate should m i n i m a l l y be based on 1) an a c t i v e data c o l l e c t i o n by a qualified h e a l t h s e r v i c e worker, 2) r o u t i n e correspondence w i t h the p a t i e n t ' s GP in cases o f a DRH. This study was part o f a l a r g e program aiming at 2000 admissions covering the whole f i e l d of i n t e r n a l medicine. Department o f C l i n i c a l Pharmacology, Odense U n i v e r s i t y , J.B. Winslews Vej 19, DK-5000 Odense C.

INCREASED D I G O X I N T O X I C I T Y IN P A T I E N T S R E C E I V I N G A M I O D A R O N E (A), VERAPAMIL (V) OR QUINIDINE (Q). A.Mordel, M.Modan and H.Halkin Digoxin toxicity, identif~ by predetermined c l i n i c a l a n d / o r E C G c r i t e r i a in 21/141 consecutive i n p a t i e n t s , m e a n age (! SD) 7 2 . 2 • receiv i n g d i g o x i n , b y a n o b s e r v e r b l i n d e d as to c o n c u r r e n t m e d i c a t i o n s , was c o n f i r m e d b y r e s o l u t i o n of signs and s y m p t o m s a f t e r d i g o x i n was discontin u e d in 16/141 (11.3%). R a t e s of t o x i c i t y were 11/40 (27.5%) in p a t i e n t s o n c o n c u r r e n t A, V or Q, v e r s u s 5/101 (4.9%) in t h o s e n o t o n the a n t i arrhythmics (p<0.001). The two g r o u p s w e r e s i m i lar w i t h r e s p e c t to age, sex, BSA, creatinine clearance (49.0 • versus 45.0!23.0 ml/min) p l a s m a N a a n d K, u n d e r l y i n g c a r d i a c c o n d i t i o n a n d d a i l y d o s e of d i g o x i n ( 0 . 1 9 9 1 0 . 0 6 5 vs. 0 . 2 1 7 !0.116 mg respectively). H o w e v e r in the AVQ group s e r u m d i g o x i n was 37.7% h i g h e r (1.46!0.86 vs. 1 . 0 6 + 0 . 8 0 ng/ml, p<0/01) while estimated fractional digoxin plasma clearance was 43.5% lower (71.1+56.2 versus 102.1!89.5 ml/min respectively, p2.0 n g / m l the r a t e s w e r e s i m i l a r (7/11 a n d 4/8 r e s p e c t i v e l y ) . W e c o n c lude that k i n e t i c i n t e r a c t i o n s of d i g o x i n w i t h A, V or Q, s i g n i f i c a n t l y e l e v a t e s e r u m d i g o x i n l e v e l a n d the o v e r a l l r a t e of d i g i t a l i s t o x i c i t y in the elderly. A, V o r Q m a y a l s o e n h a n c e the r i s k o f digitalis t o x i c i t y at s u p p o s e d l y n o n t o x i c serum d i g o x i n levels. Department of Medicine, Clinical Pharmacology U n i t a n d B i o m e t r y Unit, S h e b a M e d i c a l Center, Tel A v i v U n i v e r s i t y S c h o o l of M e d i c i n e , Tel H a s h o m e r 52621, Israel.

A 45

OP 05.04

OP 05.06

DO P R E S Y N A P T I C A L P H A - 2 A G O N I S T S H A V E S L I G H T E R CNS S I D E E F F E C T S T H A N P O S T S Y N A P T I C A G O N I S T S ? A COMPARISON OF MOXONIDINE AND CLONIDINE B. D i e t r i c h a n d W.M. H e r r m a n n

S A F E T Y P R O F I L E OF ANTIRHEUMATICS IN L O N G T E R M A D M I N I S T R A T I O N (SPALA): FIRST YEAR EXPERIENCE OF AN INTENSIVE MONITORING S Y S T E M F O R N S A I D S M. K u r o w s k i *

T h e use of a l p h a - 2 a g o n i s t s such as c l o n i d i n e in the t r e a t m e n t of h y p e r t e n s i o n is o f t e n i m p a i r e d by a d v e r s e e f f e c t s as s e d a t i o n a n d d r y mouth. Moxonidine is a new substance that, unlike clonidine, stimulates mainly presynaptic alpha-2 receptors. C l o n i d i n e ' s s e d a t i v e e f f e c t is ass u m e d t o be c o u p l e d to the p o s t s y n a p t i c a l p h a - 2 r e c e p t o r s . T h e q u e s t i o n w h e t h e r m o x o n i d i n e induces slighter sedation than clonidine was e x a m i n e d in a c o n t r o l l e d d o u b l e - b l i n d r a n d o m i z e d study performed in a t h r e e f o l d c r o s s o v e r design. S u b j e c t s w e r e 24 h e a l t h y n o r m o t e n s i v e m e n a g e d 3 0 - 4 9 years. T h e y w e r e g i v e n a s i n g l e dose of e i t h e r 0.3 m g m o x o n i d i n e , 0.3 m g c l o n i d i n e , or p l a c e b o . The d r u g ' s p o t e n t i a l s e d a t i v e e f f e c t w a s t e s t e d o n t w o levels: f u n c t i o n a l n e u r o p h y s i o l o g i c a l level w i t h the p h a r m a e o - E E G and p s y chological performance l e v e l w i t h the 3 0 - m i n P a u l i test. A s p e c t s o f w e l l - b e i n g and m o o d w e r e a l s o e x a m i n e d w i t h the E W L - E A a d j e c t i v e c h e c k list; subjects were questioned about adverse events. M e a s u r e m e n t s w e r e at 120 a n d 270 m i n p.a. B o t h a c t i v e s u b s t a n c e s s h o w e d a s e d a t i v e e f f e c t in the p h a r m a c o - E E G , but this was s t r o n g er u n d e r c l o n i d i n e . The two s u b s t a n c e s d i f f e r e d m a r k e d l y in the P a u i i test. P e r f o r m a n c e u n d e r c l o n i d i n e w a s m u c h l o w e r in the f i r s t 15 m i n compared with moxonidine. Along with other v a r i a b l e s a n a l y z e d on a d e s c r i p t i v e level, t h e s e results suggest t h a t m o x o n i d i n e has s l i g h t e r c e n t r a l n e r v o u s s i d e e f f e c t s than c l o n i d i n e .

As of April, 1988 for a p e r l o d of 2 y e a r s an expected total number of 30,000 - 40,000 inhospital and a m b u l a t o r y p a t i e n t s are m o n i t o r e d for a d v e r s e e v e n t s in 16 a m b u l a t o r y c a r e u n i t s and h o s p i t a l s for r h e u m a t i c ~ i s e a s e s in W e s t G e r m a n y (9), A u s t r l a (4) and S w i t z e r l a n d (3). For every patient, who receives an NSAID, anamnestic data including concurrent diseases and concomitant medication are recorded by physicians and nurses employed e x c l u s i v e l y for this task. The qualitative and quantitative distribus of a d v e r s e e v e n t s w i l l be a n a l y s e d and p r e s e n t e d for e v e r y NSAID and monitoring center by demographic data, indication and d u r a t i o n of t r e a t m e n t . ~,,~ January ~ ~=~ ~, ~ patients were r e g i s t e r e d ( a p p r o x i m a t e l y 70 % i n - h o s p i t a l and 30 % o u t - h o s p i t a l patients). Diagnoses pertained predominantly inflammtory diseases and degenerative rheumatic diseases (ratio 2:1). Among prescribed drugs various p r e p a r a t i o n s of diclofenac prevailed (42 %), followed by indcmetacin, acemetacin, ibuprofen, plroxlcam, ketoprofen, tenoxicam and naproxen. Event p r o f i l e s of the f i r s t y e a r w i l l be summarized and d i s c u s s e d for t h e s e drugs. * r e p o r t e d on b e h a l f of the S P A L A g r o u p I n s t i t u t f~r P h a r m a K o l o g i e , U n v e r s i t i t E r l a n g e n U n i v e r s i t ~ t s s t r a s s e 22, D-8520 Erlangen, FRG*

A F B K l i n i s c h e P h a r m a k o l o g i e G m b H Berlin, K u r f ~ r s t e n d a m m 217, i000 B e r l i n 15, FRG

OP 05.05

OP 06.01

IS THE BENZODIAZEPINE (BZD)-GABAA-RECEPTOR COMPLEX INVOLVED IN CNS-EFFECTS OF GYRASE INHIBITORS? E. Unseld, G. Ziegler, A. Gemeinhardt, U. JanSen and U. Klotz

V I T A M I N A (Retinol) ZIMBABWE

In about 1 to 2 % of patients adverse effects to the CNS such as headache, insomnia, psychotic reactions or convulsions have been reported with fluoroquinolones. It has been suggested that CNS excitation might be due to displacement of GABA from its central binding sites. We therefore tested the effects of ciprofloxacin (Cip), norfloxacin (Nor) and ofloxacin (Off) on the binding of flunitrazepam (3H-FNZ) to receptor membranes from rat brain. In a clinical study the action of Off on the EEG was investigated in 12 healthy volunteers. In this randomized, double-blind, cross-over study 400 mg of Ofl or placebo was infused for 0.5 h; 10 min later an intravenous dose of midazolem (0.075 mg/kg), the specific BZDantagonist flumazeniI (0.01 mg/kg) or placebo was added to evaluate whether or not the Off-Induced EEG changes (monitored for 3 h) could be modified by agents acting directly at the BZDGABAA-receptor complex.

During the acute life saving phase of treatment for protein energy malnutrition (PEM) vitamin A is administered. Some people reco~end that in areas of the world where PEM and vitamin A deficiencies abound retinol in oil should be administered to children every 3 to 6 months, depending on the age. It also is recommended that vitamin E should be administered since it apparently increases the efficacy of vitamin A and also protects against vitamin A toxicity by increasing storage in the liver. Marasmus and kwashiokor, severe forms of PEM, are quite common in zimbabwe and are one of the major causes of morbidity and mortality. Plasma analysis study carried out at two referral hospitals in Zimbabwe showed that 42% of malnourished children had vitamin A deficiency. The study revealed that a multi-vitamin syrup containing 2000 IU vitamin A was given routinely. A retrospective study at the hospitals of i00 cases of malnourished children showed that i00,000 IU vitamin A had been prescribed for only 8 of the children. The study brought out several issues that need to be addressed before periodic administration of retinol is recommended in Zimbabwe. These include the routine administration of sub-optimal doses of vitamin A, apparent lack of appreciation of vitamin A deficiency and exclusion of vitamin E from the essential drugs list. Vitamin A as a capsule containing 50,000 IU is on the essential drug list for zimbabwe.

In the absence (presence) of GABA (300 uM) all three gyrase inhibitors impaired BZD binding in a concentration-dependent manner; the corresponding IC 50-values were for Cip 717 (1450) uM, Nor 840 (1248) uM and Off 921 (1043) uM. In addition, 3Hflumazenil showed a maximal 32 % reduction of 14C-Ofl binding in concentrations lower than 20 uM, but could not further decrease binding at higher concentrations. The observed changes in the pharmeco-EEG indicated that Ofl had some CNS stimulating effects (e.g. decrease in slow frequencies, increase of 8-activity) which were slightly augmented by flumazenil. Coadministration of midazolam shifted the Off-induced EEG changes towards the typical BZD-like pattern. In conclusion, from our pharmacodynamic interaction study it appears likely that the CNS effects of fluoroquinolones are mediated by an involvement of the BZDGABAA-receptor complex. Supported by the Robert Bosch Foundation, Stuttgart. Dr. Margarete Fischer-Bosch-lnstitut ftlr Klinische Pharmakologie, Auerbachstr. 112, D-7000 Stuttgart 50 / FRG.

Chikuni

USE AND M A L N U T R I T I O N

IN

O, N y a z e m a N and S u l e m a n M I.

Department of Clinical Pharmacology, P O Box A178, Avondale, Harare, Zimbabwe.

A 46

OP 06.02

OP 06.04

ACE ACTIVITY IN EXPERIMENTAL SCHISTOSOMIASIS UNDER THE INFLUENCE OF PRAZIQUANTEL &/OR CAPTOPRIL:

PLASMODIUM F A L C I P A R U M : OF I S O L A T E S FROM A L I G A R H

M.T. Khayyal, S. Saleh, A.A. Metwally*, & M.R. Mahmoud*

Malaria due to Plasmodium falciparum represents a major health problem in India. This study was aimed to identify and isolate drug resistant strains of Plasmodium falciparum in and around Aligarh region of India. The drugs -used for sensitivity study were chloroquine and mondest hy lamodiaquine (MADQ) . Drug coated polystrene plates provided as a gift by Dr. Le Bras, Institut De Medicine et D' Epidemiologie Africaines et Tropicales were used in the test. Forty eight isolates of P. falciparum obtained from cases of malaria in Aligarh were tested. The semi-micro test technique of Le Bras & Deloron (Am. J. Trop. Med. Hyg., 32(3), 447, 1983) was applied. Chloroquine was used in the range of 25 nM/litre to 1600 nM/litre and M A D Q in the range of 10 nM/litre to 400 nM/litre Out of the for ty-eight isolates, five were found to be resistant to chloroquine but all were sensitive

H.M.Khan,

S. Botros*

Murine schistosomiasis is usually associated with hepatic granulomatous lesions together with high serum and granuloma ACE activity. Praziquantel (PRZ) which is known to reduce granuloma size was studied to show whether this effect is related to changes in ACE activity. Furthermore, csptopril was studied to show whether by inhibiting ACE activity, the drug could also affect granuloma size. PRZ, Captopril, and their combination led to significant reduction in liver granuloma size, and in ACE activity in serum and liver granuloma. However, in normal mice, captopril w a s shown to increase rather than decrease serum ACE. The decrease in ACE activity by PRZ was correlated with its curative effect in infected mice. However, in exp~rimental!y induced pulmonary granu!omata, the drug reduced granuloma size without affecting ACE activity of either serum or granuloma. It may be concluded that reduction in ACE activity may be beneficial as far as diminution of granuloma size is concerned, and irreSpective of whether there is an active infection or not. Captopril may thus be safely used in bilharziel infections without the risk of adversely affecting the granulomatous lesions.

to

H.Kumar,

DRUG SENSITIVITY REGION OE I N D I A .

A.A.Mahdi

and

S.

IN-VITRO

Ahmad

MADQ.

Department of Microbiology, J . N. Medical College, Aligarh Muslim University, A l i g a r h - 202 002. I n d i a .

Pharmacology Depts, Faculty of Pharmacy, Cairo University and *Theodor-Bilharz Inst., Embaba, Cairo

OP 06.05

OP 06.03 M.H~, M.I~i. FD/~IIR, H. I ~ , D.W.G.h~

S d ~ i s i,~ ~

H.M. ALI, T.ELST~IG,

in.t~c~ ~ .

is a ~j~r h~_~ ~ m~..z~, ~

~=~..~

~ 7 ~ .

cide) ~hich ~as ~ to be as effecti~ a m creeper t h ~ Biltrici~. we h ~ ~ c m t ~ d th~ ~ c ~

Bil1~i~

~

hi~-~r blood le~_Is at all t ~

with a larg~ ~

the differer~es %~re not .s~' t ~

w~

wi~ ~

.~s

(0-24 ho~rs)

- the curv~ (l~_I;)~

cide ~ , cant. ~

diet ~

~to-

to Di%~o-. y signifi-

~idm-dblv high le~is c~.l~zz~s~s

on s/milar ~

nao

In a field ~ 433 and 455 h~t/Er~tswith S.m~scri i n f e L ~ m~J.~:l Bi3.~ &D i s t c ~ _ r ~ ' ~ l y in a ~ sty,. Cure rates at 6 ~ m ~ s ~ r e at 99.5~ fcr beth treatrmnts a ~ 89.3% and 96.9% at 6 r ~ for Biltricic]e art1 D i % T f r ~

~ y .

we o~nzJ~ that 6bee a d j u s t , e may be r~s~d if is qi~en with local Sud~3ese diet an~ to . . p ~ s w l m o~unrz ~ li~: disa~se. Biltric~ ard Dislzs ~ s:jqal ~

c

effects; but with Bilt~ci~. f o l l ~ ~ hhses bidder bloo~ le~_Is, .%~l]~r aeses with this ~ran3

~ay ~ ~e same effects. ~ of M~dicge ard l ~ u ~ v thi~ersity of leartn~ P.O. B ~ 102 and D ~ of Clinic~l ~ ~ ' , Be/fast, ~ Irelard.

STUDIES ON EFFICACY, TOLE~ABILITY, CARDIOVASCULAR SAFETY AND KINETICS OF FANSIMEF- DURING CHEMOPROPHYLAXIS V. Navaratnam~ FANSIMEF ~ is a triple co~nbination containing mefloquine, sulphadoxine and pyrimethamine which has been used for the treatment particularly of multi-resistant fa]ciparum malaria. T h e objective of the study was to assess the efficacy, tolerability and cardiovascular safety of two different doses of FANSIMEFr with placebo. Methods: The study was a prospective double b]ind randomised procedure comparing 3 groups of subjects. Six subjects were randomly selected from each group for electrocardiogram studies. The studies were carried out over a period of 20 weeks. Exercise stress was measured using a bicycle ergometer, Blood plasma levels were analysed using established gas chromatographic or HPLC procedures. Results: It was found that even at the lower dose FANSIM"EF@ was completely effective in suppressing malaria parasitaemia. In general, both doses were well tolerated, however there was a five-fold reduction in the incidence of adverse drug reactions at the lower dose level in comparison to the high dose reqimen. No significant ECG changes, at rest and durin~ exercise were observed after administration of FANSIMEF at both low and high doses with the exception of one case, at the high dose, which showed transient bradycardia. The pharmacokinetics of the combination was studied and the steady state for pyrimethamine was achieved after 10-12 weeks, sulphadoxine 18-20 weeks and mefloquine 18 weeks. Conclusion: The study showed that the low dose of FANSiMEF ~ was adequate in providing protection for healthy non/semi immune persons in malarial areas, better tolerated with minimal adverse reactions and with no cardiovascular consequences. Centre for Drug Research, Universiti Sains Malaysia, 11800 Minden, Penan9, Malaysia

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ASYMPTOMATIC MALARIA PARASIT#ENIA IN AN ENDEMIG AREA OF

EFFECTS OF SINGLE DOSES OF A L P R A Z O L A M (0.75 mg), DIAZEPAM (i0 mg), R I T A N S E R I N (i0 mg) and PLACEBO, ON PSYCHOMOTOR PERFORMANCE, MEMORY, SLEEP AND CONFLICT TESTS, IN HIGH AND LOW ANXIOUS HEALTHY VOLUNTEERS. P.DANJOU,D.WAROT,L.LACOMBLEZ,P.BOUHOURS,A.J. PUECH. A possible m e c h a n i s m of action of benzodiazepines (BZD) is a decreased activity of serotoninergic systems. New anxiolytics affecting specifically 5HT pathways have been developed. The effects of Alprazolam (A), Diazepam (D), Ritanserin (R) and Placebo (P) were assessed in 23 healthy volunteers screened on Cattell Anxiety Scale. In the High Anxiety level group (HA) Cattell score was 46.27!3.25 (n = !i), and in the Low Anxiety group (LA) this score was 13.50!1.67 (n = 12).Each subject was given the four treatments at a two week interval, in a doubler blind balanced latin square design.The tests used were Critical Flicker Fusion (CFF), Choice Reaction Time (CRT), Paired Words test (PW), Visual Memory test (VM), Stroop Stress test, Visual Analogue Scales (VAS) and Electrodermogram (EDG) and were performed before and 2h30 after dosing . The only anxietyrelated difference was a decreased C F F v a l u e before treatment in the HA group (- 1.4 Hz). Both BZD decreased CFF , A increased CRT , A and D decreased visual memory , A d e c r e a s e d short term memory score , and both BZD increased sedation on self-rating scales.Ritanserin d e c r e a s e d CFF but did not m o d i f y neither CRT nor m e m o r y tests, self-assessment was unnaffected. All active treatments h e l p e d subjects to fall asleep. While the sedative effect of benzodiazepines could be evidenced b o t h on objective and subjective variables, the only test s i g n i f i c a n t l y affected by ritanserin was the CFF. This result needs further confirmation and explanation. D@partement de Pharmacologie, Hopital de la Salpitri~re, 4 7 B d de l'H6pital 75651 PARIS Cedex 13.

NIGERIA:

EFFECT OF PERIODIC MASS TREATMENT

Funmilayo 0. A d A Y I &

L.A~.SALAKO

Ij279 pupils attending 2 primary schools in a semi-urban area in South Western Nigeria took part in a series of studies to determine the status of asymptomatic malaria

p a r a s i t e i n f e c t i o n among school age c h i l d r e n , Thick finger~-prick blood films were obtained from each

p u p i l , stained w i t h G~lemsa s t a i n and examined microscop i c a l l y for presence and density of malmz~ia parasites. In one group (n=226] screened quarterly for 12 months, a

seasonal v a r i a t i o n o f the crude m l a r i a p a r a s i t e r a t e was observed w i t h the lowest r a t e , ~/0, i n January and the h i g h e s t , ?4@/0, i n July, S i m i l a r l y , the q u a r t e r l y conversion r a t e was lowestg 24%1 bstwaen A p r i l and July, Only I~/0 had no parasitaemia w h i l e 0,~/@ harboursd the p a r a s i t e throughout the period o f study, In another group, higher p a r a s i t e r a t e was found ~mong p u p i l s aged 5-7 [n=216) and 8-9 (n=244] than among the ~Froup aged 10 years and above (n=185). More than ?e/~ of the cases had a parasite density of 8~O00/ul and below~ and this was independent of age. Children in a third study were subdivided into 2 groups. In one group of 128 pupils~ only these with malaria parasitaemia were given t h e r a p e u t i c dose of ohloroquine phosphate w while all the pupils in the second group (n=181) were treated. Full sensitivity to chloroquine was observed; and parasitaemia did not reappear until after 21 days fallowing drug a~inistration in both the treated and the untreated groups. This study shewed that (i] in ir~-vivo tests of antimalarial drugs in this endemic area, a~'~-d--~y-ytest would be able to exclude re-infection and (ii) when parasite density is below 5~OOO/ul in f e b r i l e c h i l d r e n , a search f o r an

a l t e r n a t i v e a e t i o l o g y i s very i m p o r t a n t , Department o f Pharmacology, Ogun S t a t e U n i v e r s i t y Teaching H o s p i t a l , P, MIB, 2001 ! Segemu, N i g e r i a ,

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EFFECTS OF SINGLE ORAL DOSES OF BROMAZEPAM, BUSPIRONE, AND CLOBAZAM ON PERFORMANCE TASKS AND MEMORY M. B0urin, J.L. Auget, M.C. Colombel and C. Laronsse The effects on memory and psychomotor Performance and the subjective effects of three anxiolytic drugs (bromazepam 3 mg, buspirone I0 mg and clobazam I0 mg p.o.) have been evaluated in a double blind placebo-controlled, cross over study in 20 healthy volunteers. At each session, measurements were made prior, + 2 H and + 6 H after drug administration. The psychometric tests used in this study were the images test, the digit/symbol substitution test (DSST), choice reaction time (CRT) and critical fusion frequency (CFF). Free recall after 30 secondes in the + 2 N session was altered for the three drugs compared with placebo (p < 0,01) but in the + 6 H session only bromazepam showed a significant difference (p <0,01). The number of symbols reproduced by subjects during DSST was significantly decreased by bromazepam and buspirone when compared with placebo (p < 0,01) wether clobazam did not showed any difference with placebo. Analysis of variance for the four treatments showed no difference between them either at recognition time or motor response in CRT. None of t h e anxiolytic drugs altered the performance of subjects during CFF (except bromazepam at + 6 H thus clobazam increased performances).

EFFECTS OF BUSPIRONE A~D DIAZEPAM ON EXOGENOUS, N~SOGENOUS AND ENDOGENOUS COMPONENTS OF CEREBRAL EVOKED POTENTIALS IN HUMANS. M.J. Barbanoj, M. Martfn, E. Gorina, J. Torrent, F. Jane.

Conclusion : Benzodiazepines studied and buspiroae disturbed acquision phenomena or restitution of memory. However only bromazepam and buspirone significantly modified performance during DSST and they disturbed the recognition and processing of sensory data.

Departement de Pharmacologie Ciinique C.H.U. 44035~NANTES CEDEX FRANCE

Benzodiazepines (Bzd), despite their effectiveness in the treatment of anxiety disorders, disrupt information processing at different levels. Buspirone (B) is a new anxiolytic compound pharmacologically unrelated to Bzd which seems to be devoid of an objective sedative pattern in its central effects. The aim of this study was to evaluate the activity of anxiolytic equipotent doses of B and diazepam (D) on exogenous, mesogenous and endogenous components of cerebral evoked potentials. After a habituation session, single oral doses of B (15 mg) and D (15 mg) were administered in a randomized, cross-over (washout period: one week), double-blind fashion under placebo-controlled conditions to 16 healthy subjects of both sexes. At O, 90 and 180 minutes, brain stem auditory (BSA), LED-flash long latency (LFL) and P300 auditory oddball -2:8- (F3) evoked potentials were registered in standard -stimulation, recording and quantificationconditions. Furthermore, subjective reports were assessed by means of Visual Analogue Mood Scales, P.O.M.S. and EES-cheek lists. D produced a latency increase of p e a k V on BSA, an amplitude increase of PI00-PI50 complex (occipital), an amplitude decrease and latency increase of P200 and N270 (central) on LFL, as well as an amplitude decrease and latency increase of P3, when compared to placebo (P) and B, the latter not being different from P. However, although subjective assessments after D showed the greatest decrease in "activity" and increase of both "sleepyness" and a number of side-effects, B could also be differentiated from placebo in these self-reports. These results provide further evidence that the mechanisms of action of B and Bzd ly on different neurobiological basis. Dep Farmacologia i Psiquiatria, UAB. Farmacol Clin, Hosp Sant Pau. Av. M Claret, 167. 0gO25-Barcelona. Spain.

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C O R R E L A T I O N OF T H E EFFECTS A N D CONCENTRATIONS OF D I A Z E P A M (DZ) M E A S U R E D CHEMICALLY A N D BY R A D I O R E C E P T O R ASSAY (RRA) M.J.Mattila, M.E.Mattila and E.-L. Hirvisalo Slowed saccadic eye movements after oral single doses of D Z correlate to its plasma peak concentrations (P. Bittencourt et al., Brit. J. din. Pharmac. 12, 523, 1981). W e have related plasma D Z levels to its effects on complex skilled performances and subjective visual analogue (VAS) ratings in a double-blind crossover study with 12 healthy subjects. Plasma D Z was assayed chemically (GLC, HPLC) and by radioreceptor assay (RRA) (K. Aranko et al., Eur. J. Clin. PharmacoL 28, 559, 1985) and D Z effects were measured at 1.5, 3, 4.5 and 6 h post intake of 15 mg D Z in capsule. Objective tests were digit symbol substitution (DSS), flicker fusion (CFF), Maddox wing (MW), tracking error severity (TES), and cumulative choice reaction time (RT). Drowsiness, clumsiness, passiveness