Polymixin B

From Cow
Polymixin B.jpg

Polymixin B is an antimicrobial drug effective against Gram-negative bacterial diseases.

In bovine medicine, it is a constituent of many proprietary drugs for conjunctivitis and otitis externa. It is also a drug used for prevention of sepsis.

Polymixin B is a cyclic cationic polypeptide antibiotic that binds to the lipid A subunit of endotoxin molecules with high affinity, preventing the interaction of endotoxin with humoral and cellular receptors and the resultant activation of inflammatory pathways[1]. This drug inhibits activation of nuclear factor kappa B (NK-kB) by neutralising LPS. Kappa B is one of the primary cytokine transcription regulators during Gram-negative sepsis[2].

Treatment with polymixin B in high-dose intravenous trials has shown its efficacy in reducing endotoxaemia and increasing survival rates in cattle[3].


  1. Shimokawa K et al (2012) Adsorption of various antimicrobial agents to endotoxin removal polymyxin-B immobilized fiber (Toraymyxin®). Colloids Surf B Biointerfaces 90:58-61
  2. Brown, MA & Jones, WK (2004) NF-kappa B action in sepsis: the innate immune system and the heart. Front Biosci 9:1201-1217
  3. Alemu S & Zewde BM (2012) Prevalence and antimicrobial resistance profiles of Salmonella enterica serovars isolated from slaughtered cattle in Bahir Dar, Ethiopia. Trop Anim Health Prod 44(3):595-600