Study on the drug–drug interaction of antituberculosis drugs — PA-824 and moxifloxacin based on pharmacokinetics in rats by LC–MS/MS

Abstract

A simple, rapid, and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the simultaneous quantitation of PA-824 and moxifloxacin in rat plasma using carbamazepine as an internal standard (IS). The sample preparation involved a one-step protein precipitation method with methanol. The separation was performed on Inertsil® ODS3 C18 column (150 mm × 4.6 mm, 5 μm) and maintained at 30 °C. The mobile phase consisted of 0.1% formic acid in acetonitrile–water (90:10 v/v) with fast isocratic elution at a flow rate of 0.6 mL/min and a run time of 10 min. A mass spectrometer was run in the positive ion electrospray ionization (ESI) mode using multiple reaction monitoring (MRM) to monitor the mass transitions. The MRM transitions were chosen to be m/z 360.1 → m/z 175.0 for PA-824, m/z 402.0 → m/z 383.9 for moxifloxacin, and m/z 237.1 → m/z 194.0 for IS. The method was fully validated in terms of selectivity, linearity, accuracy, precision, matrix effect, recovery, and stability, respectively. The method was successfully applied to drug–drug interaction (DDI) study of PA-824 and moxifloxacin in rats. The results show that the main pharmacokinetic parameters of PA-824, namely, Tmax, t1/2, and AUC(0–t), increased more in the PA-824 and moxifloxacin group than in the PA-824 group. However, there were little changes in the main pharmacokinetic parameters of moxifloxacin from single and combined groups.