Determination of Coblopasvir in Mouse Plasma by Liquid Chromatography–Tandem Mass Spectrometry and Its Application to Pharmacokinetic Study

This study aims to develop and validate a highly sensitive and high-throughput liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of coblopasvir in mouse plasma and to apply it to a pharmacokinetic study. Plasma samples (10.0 μL) were deproteinized by protein precipitation using acetonitrile. Chromatographic separation is achieved on a Waters CORTECS C8 column with a total run time of 3.0 min. Mass spectrometric detection employed electrospray positive ionization (ESI+) and multiple reaction monitoring (MRM) modes, with quantitative ion transitions of m/z 783.5 → 609.2 (coblopasvir) and m/z 455.2 → 164.9 (internal standard verapamil). The method was fully validated according to the bioanalytical guidelines and subsequently applied to a pharmacokinetic study in ICR mice following oral administration of coblopasvir at a dose of 10 mg/kg. The method exhibited excellent linearity over the concentration range of 2.00-5000 ng/mL. Intraday and interday accuracy (relative error [RE]) ranges from -9.3% to 9.3%. This study presents the first dedicated LC-MS/MS method for the determination of coblopasvir, offering distinct advantages including an extremely low plasma volume requirement (10 μL), high throughput (3 min per sample), and operational simplicity. The validated method provides a reliable and efficient analytical tool for nonclinical and future clinical studies of coblopasvir.