Liquid chromatography-tandem mass spectrometric assay for the mutated BRAF inhibitor dabrafenib in mouse plasma

A quantitative bioanalytical liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay for the mutated BRAF inhibitor dabrafenib was developed and validated. Plasma samples were pre-treated using protein precipitation with acetonitrile containing PLX4720 as internal standard. The extract was directly injected into the reversed-phase chromatographic system after dilution with water. The eluate was transferred into the electrospray interface with positive ionization and the analyte was detected in the selected reaction monitoring mode of a triple quadrupole mass spectrometer. The assay was validated in a 2-2000 ng/ml calibration range with r(2) = 0.993 +/- 0.002 for linear regression with quadratic weighting (n = 5). Within day precisions (n = 6) were 3.3-5.2%, between day (3 days; n = 18) precisions 4.7-8.2%. Accuracies were between 95-104% for the whole calibration range. The drug was sufficiently stable under all relevant analytical conditions. Finally, the assay was successfully used to determine drug pharmacokinetics in mice. (C) 2013 Elsevier B.V. All rights reserved.