Are there any ways around the exposure-limiting nephrotoxicity of the polymyxins?

- Risk factors for nephrotoxicity include nephrotoxins, dose and serum concentration.
- Both polymyxins are nephrotoxic; polymyxin B may be less nephrotoxic than colistin.
- Ascorbic acid might help prevent polymyxin-induced nephrotoxicity.
- Nephrotoxicity is usually mild and reversible.
- Clinical efficacy and safety of polymyxin combination regimens should be evaluated.

The polymyxins (colistin and polymyxin B) have emerged over the past 20 years as essential antibacterial agents that often are the only remaining active class against troublesome multidrug-resistant Gram-negative bacilli such as carbapenem-resistant Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacteriaceae. The utility of this class is limited by its dose-dependent nephrotoxicity, which can occur in more than one-half of patients receiving therapy with either agent. Strategies are urgently needed to optimise the use of this class of agents to ensure optimal activity while minimising the treatment-limiting nephrotoxicity. This review will focus on risk factors for polymyxin-associated nephrotoxicity, potential strategies for limiting this exposure-dependent toxicity and, finally, unknowns and future research directions pertinent to this topic.