Determination of SK7324, a new class of hepatitis C virus inhibitor, in rat plasma by UPLC-MS/MS and its application to the pharmacokinetic study of SK7324.

In this study, a sensitive method for quantitation of the unique small-molecule inhibitor of hepatitis C virus SK7324 in rat plasma has been established using ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI/MS/MS). SK7324 and internal standard (tramadol) in plasma sample was extracted using acetonitrile. A centrifuged upper layer was then evaporated and reconstituted with the mobile phase of 0.5% formic acid-acetonitrile (35:65, v/v). The reconstituted samples were injected into a C reversed-phase column. Using MS/MS in the multiple reaction monitoring (MRM) mode, SK7324 and tramadol were detected without severe interference from rat plasma matrix. Detection of SK7324 in rat plasma by the UPLC-ESI/MS/MS method was accurate and precise with a quantitation limit of 1.0 ng/mL. The validation, reproducibility, stability, and recovery of the method were evaluated. The method has been successfully applied to pharmacokinetic studies of SK7324 in rat plasma. Pharmacokinetic parameters of SK7324 were evaluated after intravenous (i.v.; at doses of 5 mg/kg) and oral (p.o.; at doses of 10 mg/kg) administration of SK7324 in rats. After p.o. administration (10 mg/kg) of SK7324, (Fraction absorbed) value was approximately 87.1%.