Colistin Pharmacokinetics in Pediatrics

To the Editor—Mesini et al have recently published an article relying on colistin area under the time-concentration curve (AUC) in children, leading to dosing regimen recommendations [1]. Measured colistin concentrations are surprisingly high and uncontrolled degradation of the infused prodrug (colistin methanesulfonate [CMS]) may be suspected, but this is impossible to assess as CMS concentrations are not reported. Yet there is no doubt that AUC estimate based on 2 concentrations is inappropriate.