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Drug interactions with azithromycin and the macrolides: an overview
1Colleges of Pharmacy and Medicine, Ohio State University, Columbus 43210, USA.
Abstract:
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.
Insights
Azithromycin exhibits fewer drug interactions compared to other macrolides, particularly with theophylline and cytochrome P450 IIIA substrates. This macrolide antibiotic offers a safer co-administration profile for patients with bacterial infections.
Area of Science:
- Pharmacology
- Microbiology
- Drug Interactions
Background:
- Macrolide antibiotics are commonly prescribed for bacterial infections.
- Co-administration with other drugs can lead to significant drug interactions.
- Understanding these interactions is crucial for patient safety.
Purpose of the Study:
- To review evidence on drug interactions between macrolides and frequently co-administered pharmacologically active compounds.
- To compare the interaction profiles of different macrolides, focusing on azithromycin.
- To elucidate the mechanism behind azithromycin's reduced interaction potential.
Main Methods:
- Literature review of published evidence on macrolide-drug interactions.
- Analysis of pharmacokinetic and pharmacodynamic data.
- Focus on interactions with theophylline, cyclosporin, antiepileptics, terfenadine, warfarin, oral contraceptives, gastritis agents, and zidovudine.
- Investigation of the role of cytochrome P450 IIIA enzyme system.
Main Results:
- Erythromycin and clarithromycin show significant interactions with theophylline.
- Azithromycin, spiramycin, and rokitamycin do not significantly affect theophylline pharmacokinetics.
- Azithromycin demonstrates minimal clinically significant adverse effects with most other reviewed agents, unlike other macrolides.
- Azithromycin's reduced interaction profile is attributed to its inability to induce or bind to the cytochrome P450 IIIA enzyme system.
Conclusions:
- Azithromycin exhibits a more favorable drug interaction profile compared to other macrolides.
- The lack of interaction with the cytochrome P450 IIIA system explains azithromycin's safety.
- Azithromycin offers a safer therapeutic option when co-administration with other medications is necessary.