LC-MS/MS method assay for simultaneous determination of the pretomanid and pyrazinamide in rat plasma by LC-MS/MS: Assessment of pharmacokinetic drug-drug interaction study

In the present study, an LC-MS/MS method allowing to quantify pretomanid and pyrazinamide simultaneously in rat plasma was developed. Chromatographic separation was achieved on an Agilent Eclipse plus C18 column (100 mm × 2.1 mm, 3.5 μm; Agilent, USA) and maintained at 30 °C. Multiple reaction monitoring (MRM) using positive-ion ESI mode to monitor ion transitions of m/z 360.1 → m/z 175.1 for pretomanid, m/z 124.1 → m/z 81.0 for pyrazinamide, m/z 172.1 → m/z 128.1 for metronidazole (IS). The calibration curves showed good linear relationships over the concentration range of 50–7,500 ng mL⁻¹ for pretomanid and 500–75,000 ng mL⁻¹ for pyrazinamide. The precision and accuracy were below 15% and within ±15% of the nominal concentrations, respectively. The selectivity, recovery and matrix effect of this method were all within acceptable limits of bioanalytics. The method was applied to the analysis of plasma samples from pharmacokinetic studies in rats. The results show that the main pharmacokinetic parameters of pyrazinamide, namely, T max , t1/2, and AUC(0–t), decreased in the combined group than in the alone group.