Development and validation of an ultra-performance liquid chromatography-tandem mass spectrometry method for the determination of baloxavir in rat plasma and its application to pharmacokinetic studies

In this study, an ultra-performance liquid chromatography-tandem mass spectrometry method was established for the development and validation of baloxavir acid (BXA) concentrations and the active ingredients of the antiviral drug baloxavir marboxil (BXM). Further, the method was applied to study the pharmacokinetics of BXA. BXA was determined by the electrospray ionization multiple reaction monitoring positive ion mode, and the mass-to-charge ratios (m/z) of BXA and internal standard baloxavir-d4 were 484.2 -> 247.2 and 488.1 -> 247.2. An Oasis max online column (2.1 x 20 mm, 30 mu m) was used with 1% formic acid in water (A) and 2% formic acid in acetonitrile (B) as mobile phases at a flow rate of 0.5 mL center dot min(-1) for chromatographic separation. The linearity was good in the range of 3-200 ng center dot mL(-1) (r = 0.9994), with 3.00 ng center dot mL(-1) lower limit of quantification. The relative standard deviation of the inter-assay precision was less than or equal to 6.51%, and the accuracy was in the range of 91.28%-104.29%. This method is suitable for the determination of BXA and for performing pharmacokinetic studies in clinical research.

Automated summary

An ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the determination of baloxavir acid (BXA) and baloxavir marboxil (BXM) concentrations, as well as for studying the pharmacokinetics of BXA. The method showed good linearity and accuracy, with a lower limit of quantification of 3.00 ng/mL. This method is suitable for clinical research on BXA determination and pharmacokinetic studies.