BENZODIAZEPINES: A SATURATED MARKET? Are the latest additions any better than those already available?

The benzodiazepine market appears to be saturated with many 'me-too' and 'me-again' products which tend to confuse prescribers and may harm patients. One of the latest benzodiazepine preparations is prazepam which clinical trials have shown to be as active as diazepam. This is not surprising as they are both metabolised to the same active metabolite, desmethyldiazepam (although the manufacturer calls it desalkylprazepam), as are clorazepate, ketazolam, chlordiazepoxide and medazepam. Another new product is a slow-release diazepam which is marketed with the claim that 'this could well mean fewer side effects.' No supporting evidence is given, however. The lOmg diazepam capsule can be given once daily, but since the half-life of diazepam is 30-80 hours (and that of desmethyldiazepam is 40-200 hours) the pharmacokinetic 'superiority' of this new slow-release product is of no advantage to those patients who take the standard tablet once daily at night. Furthermore, the cost of this formulation exceeds that of standard tablets. Drugs and Therapeutics Bulletin 20: I 7 (20 Aug 1982)

4

!NPHARMA 18 Sep 1982

0156-2703/82/0918-0004/0$01.00/0 '') ADIS Press