Development and validation of a UPLC-MS/MS method for determination of motesanib in plasma: Application to metabolic stability and pharmacokinetic studies in rats.

Motesanib is a potent angiokinase inhibitor, has shown potential therapeutic effects against various cancers. An accurate, reproducible, rapid, specific, sensitive, and valid ultraperformance liquid chromatography-tandem mass spectrometry method was established to quantify motesanib in rat plasma. Motesanib and linifanib (used as an internal standard; IS) were extracted from plasma by liquid-liquid extraction using tert-butyl methyl ether as extracting agent. Chromatographic separation was performed on Acquity™ UPLC BEH™ C column (100 mm × 2.1 mm i.d., 1.7 μm; Waters Corp., USA) using a mobile phase comprising of 0.1% formic acid acetonitrile: ammonium acetate (90:10 v/v) eluted at a flow rate of 0.25 mL/min. The electrospray ionization in the positive-mode was used for sample ionization. In the multiple reaction monitoring mode, motesanib and the IS were quantified using precursor-to-product ion transitions of m/z 374.03 → 212.02 and m/z 376.05 → 251.05, respectively. The ranges of the calibration curves were 5.0-1000.0 ng/mL with coefficient of determination of ≥0.998. The method was validated by following recently implemented USFDA guideline for bioanalytical method validation. The lower limit of quantification was 5.0 ng/mL, whereas the intra-day and inter-day accuracies of quality controls (QCs) samples were ranged between 88.91% to 95.65% and 90.20% to 102.17%, respectively. In addition, the linearity, recovery, precision, and stability parameters were found to be within the acceptable range. The method was applied successfully to in vitro microsomal metabolic stability and preliminary oral pharmacokinetic studies in rats. The applied UPLC/MS/MS method was found to be adequately sensitive and therefore suitable for application in routine motesanib pharmacokinetic studies.