Determination of A Novel Selective B-RafV600E Inhibitor (LXK4) in Dog Plasma by HPLC–MS/MS and its Application in a Pharmacokinetic Study

Abstract

A rapid and sensitive HPLC–MS/MS assay was established and validated to quantify LXK4, a novel potent B-RafV600E inhibitor in dog plasma. The samples prepared by liquid–liquid extraction using ethyl acetate were separated on a Phenomenex C8 column with mobile phase of water–methanol. LXK4 and IS were all detected by monitoring the precursor → product ion transition of m/z 413.4 → 345.4 and 401.3 → 333.3, respectively, using multiple reaction monitoring (MRM) scan mode with positive ionization mode. The liner calibration curves for LXK4 in dog plasma ranged from 0.5 to 1000 ng mL−1 with the lower limit of quantification of 0.5 ng mL−1. The intra- and inter-day precisions were lower than 12.0%, and the accuracy ranged from −4.6 to 9.5%. The validated assay was successfully used as a new approach to study the pharmacokinetics of LXK4 in beagle dogs and the oral bioavailability of LXK4 was determined to be 30.5%.