Antibiotic which inhibits PKC via bacterial membrane binding mechanism. Effective against gram negative bacteria. Polymyxins bind to the cell membrane and alter its structure making it more permeable. The resulting water uptake leads to cell death. They are cationic, basic proteins that act like detergents (surfactants}. Side effects include neurotoxicity and acute renal tubular necrosis. it is commonly used in the topical first aid preparation Neosporin. Polymyxin B belongs to a family of polypeptides with attached fatty acid, acting as a cationic detergent at physiological pH, both hydrophilic and hydrophobic properties. Polymyxin B is bactericidal for gram-negative, and has little to no effect on gram-positive since cell wall is too thick to permit access to membrane
Polymyxin B alters cytoplasmic membrane permeability by binding to a negatively charged site in the lipopolysaccharide layer which has an electrostatic attraction for the positively charged amino groups in the cyclic peptide portion. The fatty acid portion dissolves in hydrophobic region of membrane and disrupts membrane integrity, resulting in leakage of cellular molecules and inhibition of cellular respiration. Polymyxin B binds and inactivates endotoxin.
Polymyxin B exhibits a relative absence of selective toxicity: nonspecific for cell membranes of any type, highly toxic. In addition to its antibiotic function, Polymyxin B has been used to clear endotoxin contamination in reagents.
Potency: (same/more than) 6500 Polymycin B units/mg
pH: 5.0-7.0
Working Concentration: 50mg/ml
Content of Phenylalanine:
9-12%
Conform to the USP30/EP5.0 specifications.
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