Development and Validation of an HPLC-MS/MS Method for Rapid Simultaneous Determination of Cefprozil Diastereomers in Human Plasma

Background. Both cis- and trans-cefprozil have antimicrobial activity, but their potencies are quite different. It is therefore necessary to develop a sensitive method to simultaneously determine both isomers for pharmacokinetic and bioequivalence studies. Methods. An LC-MS/MS method, using stable isotope-labeled cefprozil as the internal standard, was developed and validated. The analytes were extracted from plasma by protein precipitation and separated on a reverse-phase C-18 column using a gradient program consisting of 0.5% formic acid and acetonitrile within 4 min. The mass spectrometry acquisition was performed with multiple reaction monitoring in positive ion mode using the respective [M+H](+) ions, m/z 391.2 -> 114.0 for cefprozil and 395.0 -> 114.5 for cefprozil-D4. Results. The calibration curves were linear over the ranges of 0.025-15 mu g/mL for cis-cefprozil and 0.014-1.67 mu g/mL for trans-cefprozil. The accuracies for the cis- and trans isomers of cefprozil were 93.1% and 103.0%, respectively. The intra- and interassay precisions for the QC samples of the isomers were < 14.3%. The intra-and interassay precisions at the LLOQ were < 16.5%. Conclusions. The method was sensitive and reproducible and was applied in a pilot pharmacokinetic study of healthy volunteers.