A validated HPLC–MS/MS method for the quantification of supinoxin in rat plasma and its application to pharmacokinetic study

A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the quantification of an anticancer drug, supinoxin (RX-5902), in rat plasma. Following precipitation pretreatment using 0.1% formic acid in acetonitrile, separation was performed using a reverse phase liquid chromatography column packed with C18 (3.5 μm, 2.1 × 50 mm) along with a mobile phase of 0.1% formic acid in distilled water and 0.1% formic acid in acetonitrile at a flow rate of 0.3 mL min−1. Detection was achieved using MS/MS by multiple reaction monitoring via an electrospray ionization source at mass/charge transitions of m/z 442.30 → 223.30 for supinoxin and m/z 430.08 → 223.20 for the internal standard DGG-200064. This method demonstrated a linear standard curve (r = 0.9980) over a supinoxin concentration range of 0.0005–1 μg mL−1, as well as intra- and inter-assay precisions below 7.08% and 13.74%, respectively, and an accuracy of 1.15–4.50%. The matrix effect, recovery, and process efficiency were 93.63%, 99.70%, and 93.33%, respectively. Thus, a sensitive and reliable LC–MS/MS method was developed and validated for the quantification of supinoxin in rat plasma. This method was successfully applied to the evaluation of pharmacokinetic studies after single intravenous and oral administration of 1 mg kg−1 supinoxin in rats.