Colistin sulfate, EP (syn: polymyxin E) is a cationic, cyclic polypeptide antibiotic belonging to the polymyxin family. It is a natural product discovered in 1949 that is nonribosomally synthesized by Bacillus polymyxa subspecies colistinus Koyama. Colistin is mixture of Colistin A, B, and C. Colistin targets the bacterial cell membrane, leading to reduced permeability and cell death, and is effective against Gram-negative bacteria. Colistin sulfate, EP is soluble in water (50 mg/ml).
Colistin sulfate, EP, conforms to European Pharmacopoeia specifications.