Drug interactions with azithromycin and the macrolides: an overview.

Evidence interactions between individual macrolides and a number of pharmacologically active compounds that are frequently co-administered to patients with bacterial infections is reviewed. Theophylline is strongly associated with erythromycin interaction; clarithromycin may also interact with this drug. Azithromycin, spiramycin and rokitamycin, however, do not appear to have any effect on theophylline pharmacokinetics. The other therapeutic agents considered are cyclosporin, the antiepileptics, carbamazepine and phenytoin, terfenadine, warfarin, oral contraceptives, agents used in the management of gastritis and peptic ulcer and zidovudine. With the exception of interaction with antacids, there is no evidence that azithromycin, unlike most other macrolides, interacts with any of these agents to produce clinically significant adverse effects. The explanation for this variation appears to be azithromycin's inability to induce and bind to the cytochrome P450 IIIA enzyme system.