Simultaneous determination of ledipasvir, sofosbuvir and its metabolite in rat plasma by UPLC–MS/MS and its application to a pharmacokinetic study

• A method was validated to assay ledipasvir, sofosbuvir and its metabolite in plasma.
• The plasma sample was prepared by a protein precipitation.
• The method could also be used for clinical pharmacokinetic study.

ABSTRACTIn this work, a rapid and sensitive ultra performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) method for the determination of ledipasvir, sofosbuvir and its metabolite GS-331007 in rat plasma was developed. The analytes and the internal standard (diazepam) were separated on an Acquity UPLC BEH C18 chromatography column (2.1 mm × 50 mm, 1.7 μm) using gradient elution with a mobile phase of acetonitrile and 0.1% formic acid in water at a flow rate of 0.4 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode to monitor the precursor-to-product ion transitions of m/z 889.8 → 130.1 for ledipasvir, m/z 530.3 → 243.1 for sofosbuvir, m/z 261.5 → 113.1 for GS-331007 and m/z 285.2 → 193.1 for diazepam (IS) using a positive electrospray ionization interface. The method was validated over a concentration range of 2–500 ng/mL for ledipasvir, 10-2000 ng/mL for sofosbuvir and 10-2000 ng/mL for GS-331007. Total time for each chromatography was 3.0 min. The intra- and inter-day precision and accuracy of the quality control samples at low, medium, and high concentration levels exhibited relative standard deviations (RSD) < 10.2% and the accuracy values ranged from −9.8% to 11.2%. The method was successfully applied to a pharmacokinetic study of ledipasvir, sofosbuvir and GS-331007 in rats.