Background: Azithromycin and clarithromycin are the newest approved macrolide antibiotics.
Objective: To review the pharmacology, microbiology, and clinical utility of these agents.
Summary: These agents have distinct advantages over erythromycin, including an improved pharmacokinetic profile, less toxicity, and a wider spectrum of activity. They are approved for the treatment of respiratory tract infections and uncomplicated skin and skin-structure infections associated with specific organisms. Azithromycin is also indicated for the treatment of nongonococcal urethritis. In addition, these agents may be useful in the treatment of toxoplasmosis, mycobacterial disease, Lyme disease, and legionellosis. Clarithromycin and azithromycin have lower rates of gastrointestinal side effects than erythromycin.
Conclusions: Although clarithromycin and azithromycin show promise in the treatment of some less common infections, they should be considered alternatives to conventional agents in the treatment of respiratory tract, skin, and skin-structure infections caused by the usual pathogens. The expense of these agents may be prohibitive for routine use.