Azithromycin is a semi-synthetic, ring-expanded erythromycin produced by a Beckmann rearrangement of erythromycin oxime and reduction to the imine ether, followed by reductive methylation. Azithromycin was the first of the azalides and was designed to improve the stability and biological half-life of erythromycin A, as well as improve activity against Gram negative bacteria. Since its discovery in 1980 by Djokic and co-workers, azithromycin has enjoyed considerable therapeutic success.