Azithromycin is one of the world's best-selling antibiotics, used to treat or prevent certain bacterial infections: Acute bacterial exacerbations of chronic bronchitis in adults; acute bacterial sinusitis in adults; uncomplicated skin and skin structure infections in adults; urethritis and cervicitis in adults; genital ulcer disease in men; acute otitis media in pediatric patients; community-acquired pneumonia in adults and pediatric patients; pharyngitis/tonsillitis in adults and pediatric patients. Azithromycin should not be used in patients with pneumonia who are judged inappropriate for oral therapy because of moderate to severe illness or risk factors. A team of researchers at the Croatian pharmaceutical company Pliva, discovered azithromycin in 1980. It was patented in 1981. In 1986, Pliva and Pfizer signed a licensing agreement, which gave Pfizer exclusive rights for the sale of azithromycin in Western Europe and the United States. Pliva put its azithromycin on the market in Central and Eastern Europe under the brand name of Sumamed in 1988. Pfizer launched azithromycin under Pliva's license in other markets under the brand name Zithromax in 1991. Azithromycin is a semi-synthetic macrolide antibiotic of the azalide class. Like other macrolide antibiotics, azithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit of the bacterial 70S ribosome. Binding inhibits peptidyl transferase activity and interferes with amino acid translocation during the process of translation. Its effects may be bacteriostatic or bactericidal depending of the organism and the drug concentration. Its long half-life, which enables once daily dosing and shorter administration durations, is a property distinct from other macrolides.

N’-(desmethyl)azithromycin (CP-64434 hydrate) is the metabolite of azithromycin. Azithromycin is an effective therapeutic agent for oral treatment of sexually transmitted diseases, upper and lower respiratory tract infections, and skin and skin structure infections. 0.1 and 7.6% of azithromycin dose are excreted as N’-(desmethyl)azithromycin during a day in urine and feces, respectively. 2.9% of dose - biliary excretion.