A Sensitive LC-MS/MS Method for the Determination of Afatinib in Human Plasma and Its Application to a Bioequivalence Study.

A high performance liquid chromatography-tandem mass spectrometry assay for the determination of afatinib (AFT) in human plasma was established. A simple sample preparation of protein precipitation was used and separation was achieved on a C18 column by the gradient mixture of mobile Phase A of water (containing 0.1% ammonia) and the mobile Phase B of acetonitrile and water (V:V = 95:5, containing 0.2% ammonia). The multiple reaction monitoring mode was used to monitor the precursor-to-production transitions of m/z 486.2 → m/z 371.4 for AFT and m/z 492.2 → m/z 371.3 for AFT-d6 (internal standard) at positive ionization mode. The calibration curve ranged from 0.100 to 25.0 ng·mL-1 and the correlation coefficient was greater than 0.99. The intra- and inter-batch precision was less than or equal to 10.0%. Accuracy determined at four concentrations was in the range of 92.3-103.3%. In summary, our method was sensitive, simple and reliable for the quantification of AFT and was successfully applied to a bioequivalence study.