Colistimethate Sodium

**Semantic type:** Pharmacologic Substance

**Definition:** The sodium salt of colistimethate, a broad-spectrum polymyxin antibiotic against most aerobic Gram-negative bacteria except Proteus bacteria. Colistimethate sodium contains the pentasodium salt of the penta(methanesulfonic acid) derivative of colistin A as the major component and a small proportion of the petasodium salt of the pentamethanesulfonate derivative of colistin B. Colistins are cyclic polypeptides produced from Bacillus colistinus or B. polymyxa and function as a surfactant which penetrates into and disrupts the bacterial cell membrane, thereby resulting in bactericidal effect.

**Synonyms:** - COLISTIMETHATE SODIUM - Colimyscine - Colistin Sodium Methanesulfonate - Coly-Mycin - Pentasodium Colistinmethanesulfonate - W-1929