Determination of PF-04620110, a novel inhibitor of diacylglycerol acyltransferase-1, in rat plasma using liquid chromatography-tandem mass spectrometry and its application in pharmacokinetic studies

In this study, we developed a method for the determination of PF-04620110 (2-{(1r,4r)-4-[4-(4-amino-5-oxo-7,8-dihydropyrimido[5,4-f][1,4]oxazepin-6(5H)-yl)phenyl]cyclohexyl}acetic acid), a novel diacylglycerol acyltransferase 1 (DGAT-1) inhibitor, in rat plasma and validated it using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Rat plasma samples were processed following a protein precipitation method by using acetonitrile and were then injected into an LC-MS/MS system for quantification. PF-04620110 and imipramine (internal standard) were separated using a Hypersil Gold C₁₈ column, with a mixture of acetonitrile and 10mm ammonium formate (90:10, v/v) as the mobile phase. The ion transitions monitored in positive-ion mode [M+H]⁺ of multiple-reaction monitoring were m/z 397.0→260.2 for PF-04620110 and m/z 280.8→86.0 for imipramine. The detector response was specific and linear for PF-04620110 at concentrations within the range 0.05-50μg/mL and the signal-to-noise ratios for the samples were ≥10. The intra- and inter-day precision and accuracy of the method matched the acceptance criteria for assay validation. PF-04620110 was stable under various processing and/or handling conditions. PF-04620110 concentrations in the rat plasma samples could be measured up to 24h after intravenous or oral administration of PF-04620110, suggesting that the assay is useful for pharmacokinetic studies in rats.