Development and validation of a sensitive LC-MS/MS method for determination of gefitinib and its major metabolites in human plasma and its application in non-small cell lung cancer patients

Gefitinib, the first approved oral epidermal growth factor receptor (EGFR) inhibitor, has been demonstrated effective in cancers with EGFR active mutations. In this study, we established and validated a method for determining gefitinib and its main metabolites, M605211, M387783, M537194 and M523595 in patients with non-small cell lung cancer (NSCLC) by liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The mobile phase was water: acetonitrile (35:65, v/v) with 0.1% formic acid at a flow-rate of 0.35 mL/min, within a 3 min run time. Gefitinib and its main metabolites were separated on a X-Terra RP18 column (50 x 2.1 mm, 3.5 mu m) at 40 degrees and subjected to mass analysis using positive electro-spray ionization (ESI). The calibration ranges of gefitinib and M523595 were 0.5-1000 ng/mL, and other compounds were 0.05-100 ng/mL with the correlation coefficients (r(2)) >= 0.99. Accuracies ranged from 92.60%-107.58 and the inter- and intra-assay precision were less than 15% for all analytes in quality control samples. There was no significant matrix effect. The ranges of extraction recoveries were 86-105% for all analytes and IS. Thirty plasmas were obtained from Sun Yat-sen university cancer center. The mean plasma concentration of (+/- SD) of gefitinib M537194, M523595, M387783 and M605211 were 247.18 (+/- 140.39) ng/mL, 7.78 (+/- 6.74) ng/mL, 101.09 (+/- 93.44) ng/mL, 1.6 (+/- 0.9) ng/mL and 11.63 (+/- 4.98) ng/mL, respectively. The validated LC/MS/MS method was effectively used in the determination of gefitinib and its four metabolites in NSCLC patients. (C) 2019 Elsevier B.V. All rights reserved.