SENSITIVE AND RAPID ESTIMATION OF LAPATINIB, AN ANTICANCER DRUG IN SPIKED HUMAN PLASMA BY LC-MS/MS Original Article

Objective: The work presents a sensitive, selective and rapid determination of lapatinib, a potent anticancer drug in human plasma by liquid chromatography-tandem mass spectrometry. Methods: Liquid-liquid extraction of lapatinib and lapatinib-d4, added as an internal standard (IS) was carried out from 100 µl plasma sample. Chromatographic analysis was performed on ACE C18 (100 mm × 4.6 mm, 5 µm) column using 10 mmol ammonium formate buffer (pH 3.5) and acetonitrile (10:90, v/v) as the mobile phase. The precursor ion → product ion transitions for lapatinib (m/z 581.1 → 365.2) and IS (m/z 585.1 → 365.0) were monitored on a triple quadrupole mass spectrometer in the positive electrospray ionization mode. The method was validated in accordance with the US FDA guidelines. Results: A linear concentration range was established from 2.50-2500 ng/ml for lapatinib. The intra-batch and inter-batch precision were ≤ 4.81 %. The recovery of lapatinib and IS from plasma samples ranged from 88.7 to 95.8 % and 85.9 to 96.5 % respectively. The accuracy and precision (% CV) for the stability of lapatinib under different storage conditions showed a variation from 95.2 to 102.2 % and 1.19 to 4.35 % respectively at low and high QC levels. Under optimized chromatographic conditions, the retention time for lapatinib was 1.406 min with a total run time of 2.5 min for each sample. Conclusion: The validation results demonstrate that the method is simple, accurate, precise and reproducible. The developed method can be readily used for pharmacokinetics/bioequivalence studies in patients as well as healthy subjects.