Development and validation of a liquid chromatography-tandem mass spectrometry method to determine ulifloxacin, the active metabolite of prulifloxacin in rat and rabbit plasma: application to toxicokinetic study.

A simple, high-throughput and specific high-performance liquid chromatography-tandem mass spectrometry method has been developed and validated according to the FDA guidelines for quantification of ulifloxacin in rat and rabbit plasma. The analyte was separated on a Peerless basic C(18) column (33 × 4.6 mm, 3 µm) with an isocratic mobile phase of methanol-water containing formic acid (0.5%, v/v; 9:1, v/v) at a flow rate of 0.5 mL/min. The MS/MS detection was carried out by monitoring the fragmentation of m/z 350.500 → 248.500 for ulifloxacin and m/z 332.400 → 231.400 for ciprofloxacin (internal standard; IS) on a triple quadrupole mass spectrometer. The response to ulifloxacin was linear over the range 0.010-2.500 µg/mL in both plasma. The limit of detection and lower limit of quantification of ulifloxacin were determined in both species to be 0.0025 and 0.010 µg/mL, respectively. The method was successfully applied to quantitatively assess the toxicokinetics of ulifloxacin in rat and rabbit following a single 400 mg/kg (in rat) and 200 mg/kg (in rabbit) oral dose of the prulifloxacin.