Development and validation of an LC-MS/MS method for the determination of AZD7648 in rat plasma: Application to a pharmacokinetic study.

AZD7648 is a potent DNA-PK inhibitor that is being developed for the treatment of ovarian cancer. The study aimed to develop a simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to determine the concentration of AZD7648 in rat. AZD7648 was extracted from plasma by acetonitrile-mediated protein precipitation. The quantification was performed on a Thermo Vantage TSQ mass spectrometer with ibrutinib as an internal standard. A Waters Acquity UPLC BEH C column combined with 0.1% aqueous formic acid and acetonitrile was employed for chromatographic separation. The precursor-to-product ion transitions were m/z 421.2 > 337.2 and m/z 441.2 > 138.1 for AZD7648 and internal standard, respectively. This method was successfully validated according to the US Food and Drug Administration guidance. The calibration curve was linear over the concentration range of 0.5-1,000 ng/ml with correlation coefficient >0.999. The precision expressed as the coefficient of variation was <8.09%, while the accuracy expressed as relative error ranged from -10.00 to 9.08%. The mean recovery was >94.49%. AZD7648 was stable in rat plasma after storage under certain conditions. The validated method was demonstrated to be selective, sensitive and reliable, and has been successfully applied to the pharmacokinetic study of AZD7648 in rat plasma after oral and intravenous administration (1 mg/kg).