POSSIBLE INTERACTION OF ROXITHROMYCIN WITH WARFARIN - UPDATED REVIEW OF ADR REPORTS

Roxithromycin is an ether oxime derivative of erythromycin, but is rep orted to have a less inhibiting effect on the cytochrome P450 system t han the latter compound. Unlike erythromycin, it is considered to be d evoid of any clinically significant interactions with oral anticoagula nts. The Centre for Adverse Reactions Monitoring (CARM) of New Zealand and the Adverse Drug Reactions Advisory Committee (ADRAC) of Australi a are responsible for monitoring adverse reactions to drugs for their countries. They received 7 (CARM) and 9 (ADRAC) reports of possible in teractions of roxithromycin with warfarin during the period 1992-1995. Roxithromycin appears to have a potentiating effect on warfarin, alth ough considerably less so than erythromycin. This is likely to be part icularly clinically significant in patients receiving polypharmacy and in elderly or compromised patients.