Polymyxin B Dosing Guidelines

Introduction to Polymyxin B Dosing

The unit conversion for polymyxin B is: 1 mg = 10,000 units, which differs significantly from colistin, where 1 million IU = approximately 80 mg of colistimethate sodium (CMS) = 33 mg colistin base activity 1, 2

For bloodstream infections and pneumonia, the Infectious Diseases Society of America recommends polymyxin B 2.5-3.0 mg/kg/day divided in 2 daily IV doses (equivalent to 25,000-30,000 units/kg/day) 1
Combination therapy is strongly preferred over monotherapy for carbapenem-resistant infections, as suggested by the Journal of Microbiology, Immunology and Infection 2

A loading dose of 2-2.5 mg/kg is recommended to rapidly achieve therapeutic levels, according to clinical practice guidelines 5
The American College of Clinical Pharmacy suggests that continuous renal replacement therapy (CRRT) does not require dose adjustment for polymyxin B 5, 3
The National Kidney Foundation recommends avoiding concurrent nephrotoxic agents, particularly the combination of NSAIDs, diuretics, and ACE inhibitors/ARBs, to minimize the risk of nephrotoxicity 5
The European Renal Association suggests considering therapeutic drug monitoring where available to optimize polymyxin B dosing 2