New macrolide antibiotics: clarithromycin and azithromycin.

Clarithromycin and azithromycin are new semisynthetic macrolide antibiotics structurally related to erythromycin. They are well absorbed and widely distributed, with excellent cellular and tissue penetration. Both have a broader spectrum of activity and fewer gastrointestinal side effects than erythromycin. Currently, clarithromycin and azithromycin are approved by the U.S. Food and Drug Administration for respiratory tract infections and skin infections, but they may also have use in mycobacterial and Toxoplasma infections in patients with acquired immunodeficiency syndrome.