erythromycin

DESCRIPTION Erythromycin Topical Solution USP, 2% contains erythromycin for topical dermatologic use.‍‍‍‍‍‍​​​‍​​​​​​ Erythromycin is a macrolide antibiotic produced from a strain of Saccaropolyspora erythraea (formerly Streptomyces erythreus ). It is a base and readily forms salts with acids. Chemically, erythromycin is: (3 R *,4 S *,5 S *,6 R *,7 R *,9 R *,11 R *,12 R *,13 S *,14 R *)-4-[(2,6-Dideoxy-3- C -methyl-3- 0 -methyl-α-L- ribo -hexopyranosyl)oxy]-14-ethyl-7,12,13-trihydroxy -3,5,7,9,11,13-hexamethyl-6-[[3,4,6-trideoxy-3-(dimethylamino)-ß-D- xylo -hexopyranosyl]oxy]oxacyclotetradecane-2,10-dione. It has the following structural formula: Molecular Formula: C 37 H 67 NO 13 Molecular Weight: 733.94 Erythromycin is a white or slightly yellow crystalline powder that is slightly soluble in water, freely soluble in alcohols, acetone, chloroform, acetonitrile, ethyl acetate, and moderately soluble in ether, ethylene dichloride and amyl acetate. Each mL of Erythromycin Topical Solution USP, 2% contains 20 mg of erythromycin base in a vehicle consisting of alcohol (66%), citric acid, and propylene glycol.