Validated liquid chromatography with tandem mass spectrometry method for determination of paxalisib in mouse plasma: An application to pharmacokinetic study in mice.

A sensitive and rapid LC–MS/MS method has been developed and validated for the quantification of paxalisib in mouse plasma. A liquid–liquid extraction method was used for the extraction of paxalisib and filgotinib (internal standard, IS) from mouse plasma. A clean chromatographic separation of paxalisib and the IS was achieved on an Atlantis dC18 column using an isocratic mobile phase (10 mM ammonium formate and acetonitrile, 30:70%, v/v) delivered at a flow rate of 0.7 mL/min. The total run time was 2.5 min. Paxalisib and filgotinib were eluted at 1.21 and 0.94 min, respectively. The MS/MS transitions monitored were m/z 383.25 → 309.20 and 426.30 → 291.20 for paxalisib and filgotinib, respectively. Method validation was performed as per US Food and Drug Administration guidelines and the results met the acceptance criteria. The method was proved to be accurate and precise at a linearity range of 1.39–2287 ng/mL. The intra‐ and inter‐day precisions for paxalisib in mouse plasma were in the ranges 1.42–9.61 and 4.70–9.63%, respectively. Paxalisib was stable under a series of stability conditions. Post‐oral administration to mice, paxalisib maximum plasma concentrations were attained at 2.0 h. Paxalisib's half‐life ranged between 3.2 and 4.2 h. Paxalisib exhibited low clearance and moderate volume of distribution. Oral bioavailability was 71%. [ABSTRACT FROM AUTHOR]