Azithromycin is a semisynthetic antibiotic, the first representative of a subclass of azalides, slightly different in structure from the classical macrolides.

Obtained by a modification of the 14-membered macrolides by including the nitrogen atom in the lactone ring between 9 and 10 carbon atoms.

Ring at the same time transformed into a 15-membered, though no longer a lactone. This structural change causes a significant increase in acid resistance of the drug - to 300-fold compared with erythromycin.
Infections of the upper respiratory tract and upper respiratory tract caused by susceptible pathogens: pharyngitis, tonsillitis, laryngitis, sinusitis, otitis media, scarlet fever, infections of lower respiratory tract: pneumonia (including atypical exacerbation of chronic) bronchitis, infections of skin and soft tissue: erysipelas, impetigo, secondarily infected dermatitis, urinary tract infections caused by Chlamidia trachomatis: gonorrheal urethritis and negonoreyny, cervicitis, Lyme disease (initial stage), peptic ulcer and 12 duodenal ulcer associated with Helicobacter pylori (in combination therapy) .