Azithromycin

11 DESCRIPTION Azithromycin tablets USP contain the active ingredient azithromycin, a macrolide antibacterial drug, for oral administration.‍​‍‍‍​‍‍‍‍‍‍‍‍​‍ Azithromycin has the chemical name (2R,3S,4R,5R,8R,10R,11R,12S,13S,14R)-13-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-2-ethyl-3,4,10-trihydroxy-3,5,6,8,10,12,14-heptamethyl-11-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]-1-oxa-6-azacyclopentadecan-15-one. Azithromycin is derived from erythromycin; however, it differs chemically from erythromycin in that a methyl-substituted nitrogen atom is incorporated into the lactone ring. Its molecular formula is C 38 H 72 N 2 O 12 , and its molecular weight is 749.00. Azithromycin has the following structural formula: Azithromycin, as the dihydrate, is a white or almost white powder with a molecular formula of C 38 H 72 N 2 O 12• 2H 2 O and a molecular weight of 785.0. Azithromycin is supplied as tablets containing azithromycin dihydrate USP equivalent to either 250 mg or 500 mg azithromycin and the following inactive ingredients: croscarmellose sodium, dibasic calcium phosphate anhydrous, hypromellose, lactose monohydrate, pregelatinized starch (maize), magnesium stearate, sodium lauryl sulfate, titanium dioxide and triacetin. Chemical Structure