Liquid chromatographic determination of the plasma concentrations of cefotaxime and desacetylcefotaxime in plasma of critically ill patients

A method for the simultaneous determination of cefotaxime (CTX) and desacetylcefotaxime (DES) in plasma was developed, using acetonitrile protein precipitation and high-performance liquid chromatography (HPLC) with UV-detection at 285 nm. Desacetylcefotaxime was also analysed after conversion in highly acidic medium to its lactone form (DES-lactone). The chromatographic separation was performed on a C18 Aqua column. The lower limit of quantitation was 1 mug/ml for CTX and 0.5 mug/ml for DES and DES-lactone, using 25 mul of plasma samples. The linearity of the calibration curves was satisfactory as indicated by correlation coefficients of greater than or equal to0.990. The within-day and between-day precisions were <12% (n = 18) for the two products and the accuracy was between 88 and 101%. The developed HPLC method was applied for CTX and DES determination in plasma samples of critically ill patients after continuous intravenous infusion of CTX. (C) 2004 Elsevier B.V. All rights reserved.