The polymyxin class of antibiotics includes polymyxin B and polymyxin E (colistin), the latter of which is administered clinically as colistin methane sulfate intravenously. Although an older class of antibiotics, their use has been revitalized by the multi-drug and panresistant strains of P. aeruginosa, A. baumannii, and carbapenemresistant Enterobacteriaceae that has arisen over the last decade. Notably, these agents were shelved in the early 1970ââ¬â¢s because of high rates of nephrotoxicity and neurotoxicity relative to other available antibiotic agents. Their pharmacokinetic/pharmacodynamic properties have only recently begun to be elucidated, and antimicrobial effect is correlated with fAUC/MIC exposures. To date, these experiments have largely been undertaken in vitro or in animal infection models. As previously mentioned, 1-log reductions in colony forming unit require fAUC/MIC ratios of approximately 12.2 to 22.8 in both thigh- and lung-infection murine models. Unfortunately, the protein binding of colistin in humans, particularly critically ill patients, has not been established; therefore, for dosing strategies, a total AUC/MIC ratio of approximately 60 has been used to target drug concentrations
Last date updated on July, 2025