Merck, P4932-5MU, Polymyxin B sulfate salt

General description
Polymyxin B is a member of the polymyxin group of antibiotics, obtained from different strains of Bacillus polymyxa and related species. It contains a cyclic heptapeptide unit and a tripeptide side chain, which is N-acylated by a fatty acyl residue. Polymyxin B sulfate salt is generally used for the treatment of Gram-negative bacterial infections.
Chemical structure: peptide
Application
Polymyxin B sulfate salt has been used:
for the treatment of BAC-1.2F5 murine macrophages as an LPS (lipopolysaccharide) inhibitor
as positive and negative control during microbicidal concentration (MCC) assay

Biochem/physiol Actions
Mode of Action: Polymyxin B Sulfate binds to the lipid A portion of bacterial lipopolysaccharides†, disrupting the cytoplasmic membrane by inducing pores large enough to permit nucleotide leakage in bacterial walls. This disrupts the permeability of the cytoplasmic membrane.

Antimicrobial spectrum: Has bactericidal action on most gram-negative bacilli††, including E. Coli and on most fungi and gram-positive bacteria.
Polymyxin B sulfate has been used clinically to treat infections of the urinary tract, meninges and blood stream caused by susceptible strains of Pseudomonas aeruginosa. It also has been used in studying multidrug-resistant pathogens, as an immobilized agent for removal of endotoxins, and to induce pore formation in the membranes of cortex cells from excised sorghum roots.
Preparation Note
Polymyxin B sulfate is soluble in water at 50 mg/mL, producing a very slightly hazy, colorless to yellow solution. It has only minimal solubility in any organic solvent. For example, it has a solubility of 0.115 mg/mL in ethanol.
Other Notes
1mu,5mu
Keep container tightly closed in a dry and well-ventilated place.Keep in a dry place.
Disclaimer
As supplied, the product should be stored at 2-8°C in the dark. No change was observed in retained samples after three years′ of storage in these conditions. Stock solutions should be sterile filtered and stored at 2-8°C. They are stable at 37°C for 5 days.