Coliaxis 1 Million IU Injection COLIAXIS contains Colistimethate Sodium, a prodrug of colistin (polymyxin E), which is a cyclic polypeptide antibiotic. In vivo, colistimethate sodium hydrolyzes to active colistin. Colistin acts as a cationic detergent, binding electrostatically to lipopolysaccharides (LPS) and phospholipids in the outer membrane of Gram-negative bacteria. This disrupts cell membrane integrity, causing leakage of intracellular contents and rapid cell death. COLIAXIS is indicated for the treatment of severe, multi-drug resistant (MDR) Gram-negative bacterial infections—including those caused by Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae—for IV Use Only.