polymyxin B

Polymyxin B is a basic polypeptide antibiotic derived from the bacterium Bacillus polymyxa. It is primarily used to treat serious infections caused by susceptible Gram-negative bacteria, including those of the urinary tract, meninges (meningitis), bloodstream (sepsis), pneumonia, and eye infections. Polymyxin B acts by binding to lipopolysaccharides (LPS) in the outer membrane of Gram-negative bacteria via electrostatic interactions with lipid A phosphate groups. This displaces stabilizing calcium and magnesium ions, destabilizes the membrane structure, increases permeability, causes leakage of cellular contents, and ultimately leads to bacterial cell death. Additionally, it can bind and neutralize endotoxins released during bacterial lysis and inhibit type II NADH-quinone oxidoreductases essential for bacterial respiration[1][5][8]. It is not effective against Gram-positive bacteria or certain Gram-negative cocci such as Neisseria species[2]. The drug is poorly absorbed orally; thus it is administered parenterally or topically.

Brand names

Poly-RxPolymyxin B for Injection

Other names

polymyxin b sulfatepolymyxins B1 and B2Bacillus polymyxa antibiotic