Polymyxin B is a polymyxin antibiotic used to treat a wide variety of infections in the body. Polymyxin B was discovered in the 1940s.
- Mechanism
- Curator reviewed · 5 references
The alpha and gamma diaminobutyric acid of a positively charged polymyxin B forms an electrostatic interaction with the phosphate groups of a negatively charged lipid A on the outer membrane of a Gram negative bacterium. Calcium and Magnesium ions are displaced from phosphates of the membrane lipids, destabalising the lipopolysaccharide (LPS), increasing membrane permeability, causing cytoplasmic leaking, and killing the cell.
Polymyxin B can also bind and neutralize LPS released during bacterial lysis, preventing reactions to endotoxin.
A third activity of polymyxin B is the inhibition of type II NADH-quinone oxidoreductases in the bacterial inner membrane, which are essential for respiration.
Polymyxin is active against common Gram negative bacteria but not Gram negative cocci, Gram positive bacteria, or anaerobic bacteria.
- Primary indication
- Polymyxin B is indicated for the treatment of infections of the urinary tract, meninges, and blood stream, caused by susceptible strains of Pseudomonas aeruginosa.Curator reviewed · 20 structured indications
- First approval
- Canada, 1996 · United States, 1951
- Brand names
Resolves to
What you can answer from here — as of August 30, 2026
Which drugs share a target with Polymyxin B, and which of those have an active Phase 3 trial?
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