RIFAMPICIN INDUCES THE METABOLISM OF DIGOXIN? First r~port of an interaction in a dial.ysis.patient Although an interaction between rifampicin (rifampin) and digitoxin has been reported previously, nothing has been mentioned of a similar reaction between rifampicin and d!goxin. A 36-year-old woman on long term dialysis received O.125mg of IV digoxin at the end of each dialysis period for congestive heart failure. She achieved therapeutic serum digoxin levels and good clinical response. Howeyer, she developed a reactivation of.Ltl old pulmonary tuberculous lesion and was started on rifampicin, 450mg daily, plus isoniazid, I OO~200mg daily. One week later, her heart failure symptoms worsened and her serum digoxin levels were subtherapeutic. Despite ari increase ofIV digoxin doses to O.5mg serum digoxin levels remained subtherapeutic.Ethambutol (1 OOOmg on dialysis days) was substituted for rifampicin and serum digoxin levels rose within 48 hours to the therapeutic range. Rifampicin may induce the metabolism of digoxin during concomitant administration. Novi, C. etal.: Journal of the American Medical Abociation 244: 2521 (5 Dec 1980)

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INPHARMA 10Jan 1981

0156-2703/81/0110-0006 $00.50/0

@ADIS Press