Determination of sitafloxacin in human plasma by liquid chromatography-tandem mass spectrometry method: Application to a pharmacokinetic study

A high-performance liquid chromatographic-tandem mass spectrometric (HPLC-MS/MS) method was developed and validated to determine sitafloxacin in human plasma with dextrorphan as internal standard. Chromatographic separation was performed on a ZORBAX SB-C18 column (3.5 mu m, 2.1 mm x 100 mm) with the mobile phase of methanol/water (containing 0.1% formic acid) (46:54, v/v) at a flow rate of 0.2 mL/min. Quantification was performed using multiple-reaction monitoring of the transitions at m/z 410.2 ->. 392.2 for sitafloxacin and m/z 258.1 -> 157.1 for dextrorphan, respectively. The calibration curve was linear over the range of 5-2500 ng/mL with the lower limit of quantification of 5 ng/mL for sitafloxacin. The intra- and inter-day precisions were less than 8.3% and the deviations of assay accuracies were within +/- 4.1%. Sitafloxacin was sufficiently stable under all relevant analytical conditions. This method was successfully applied to the pharmacokinetic study of sitafloxacin in healthy Chinese volunteers. (C) 2014 Elsevier B.V. All rights reserved.