In medicine, azithromycin is a "semi-synthetic macrolide antibiotic structurally related to erythromycin. It has been used in the treatment of Mycobacterium avium intracellular infections, toxoplasmosis, and cryptosporidiosis."
Azithromycin was patented in 1982. Zithromax was approved by the Food and Drug Administration for Pfizer in 1991. Non-authorized generic drugs manufactured by Teva, Sandoz, and Abraxis were approved in the United States starting in 2005.