Colistin and polymyxin B: peas in a pod, or chalk and cheese?

Clin Infect Dis. 2014 Jul 1;59(1):88-94. doi: 10.1093/cid/ciu213. Epub 2014 Apr 3.


Colistin and polymyxin B have indistinguishable microbiological activity in vitro, but they differ in the form administered parenterally to patients. Polymyxin B is administered directly as the active antibiotic, whereas colistin is administered as the inactive prodrug, colistin methanesulfonate (CMS). CMS must be converted to colistin in vivo, but this occurs slowly and incompletely. Here we summarize the key differences between parenteral CMS/colistin and polymyxin B, and highlight the clinical implications. We put forth the view that overall polymyxin B has superior clinical pharmacological properties compared with CMS/colistin. We propose that in countries such as the United States where parenteral products of both colistin and polymyxin B are available, prospective studies should be conducted to formally examine their relative efficacy and safety in various types of infections and patients. In the meantime, where clinicians have access to both polymyxins, they should carefully consider the relative merits of each in a given circumstance.

Keywords: colistin; differing clinical pharmacological behaviors; polymyxin B; therapeutic implications.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Administration, Intravenous
  • Anti-Bacterial Agents / adverse effects
  • Anti-Bacterial Agents / pharmacokinetics*
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use*
  • Bacterial Infections / drug therapy
  • Clinical Trials as Topic
  • Colistin / adverse effects
  • Colistin / pharmacokinetics*
  • Colistin / pharmacology
  • Colistin / therapeutic use*
  • Humans
  • Polymyxin B / adverse effects
  • Polymyxin B / pharmacokinetics*
  • Polymyxin B / pharmacology
  • Polymyxin B / therapeutic use*


  • Anti-Bacterial Agents
  • Polymyxin B
  • Colistin