Development of a validated bioanalytical method for the simultaneous estimation of ornidazole and miconazole in rat plasma by LC-MS/MS and its application to a pharmacokinetic study

A highly sensitive, accurate, and robust LC-MS/MS method was developed and validated for the simultaneous determination of ornidazole (ODZ) and miconazole (MCZ) in rat plasma using metronidazole (MTR) as an internal standard (IS). The analyte and IS were extracted from plasma by precipitating protein with acetonitrile and were chromatographed. The mobile phase was acetonitrile and 0.1% formic acid (75:25 v/v). The total run time was 3 min, and the injection volume was 5.0 mu L. Multiple reaction monitoring (MRM) mode was used, in which the transitions of m/z 417.10 -> m/z 160.90 for MCZ, m/z 220.10 -> m/z 127.90 for ODZ, and m/z 172.10 -> m/z 128.1 for IS were monitored. The linearity range of MCZ was 0.15 - 250.0 ng/mL and 3.0-250.0 ng/mL for ODZ. The lower limits of quantification (LLOQ) were found to be 0.05 ng/mL for MCZ and 1.0 ng/mL for ODZ in rat plasma. Recoveries of MCZ ranged between 75.33% - 94.25% and ODZ ranged between 75.33% - 95.54%. The quality control sample accuracy and precision (intra-day and inter-day) were -1.25% to 1.68% and 3.01% to 6.44% for MCZ and -1.31% to 1.88% and 3.34% to 6.98% for ODZ, respectively. The analytes and IS were stable during all sample storage and analysis procedures. Graphical Abstract