Liquid chromatography-tandem mass spectrometric assay for the cyclin-dependent kinase inhibitor AT7519 in mouse plasma

A quantitative bioanalytical liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay for the cyclin-dependent kinase inhibitor AT7519 in mouse plasma was developed and validated. Plasma samples were pre-treated using protein precipitation with acetonitrile containing rucaparib as internal standard. After dilution with water, the extract was directly injected into the reversed-phase LC system. 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 5-10,000. ng/ml calibration range using double logarithmic calibration, 5. ng/ml was the lower limit of quantification. Within day precisions (n= 6) were 2.9-5.6%, between day (3 days; n= 18) precisions 3.2-7.2%. Accuracies were between 95.9 and 99.0% for the whole calibration range. The drug was stable under all relevant analytical conditions. Finally, the assay was successfully used to determine plasma pharmacokinetics after intraperitoneal administration of AT7519 in mice with neuroblastoma xenografts.