Isolation and structural characterization of degradation products of afatinib dimaleate by LC-Q-TOF/MS/MS and NMR: cytotoxicity evaluation of afatinib and isolated degradation products.

Afatinib is an irreversible tyrosine kinase receptor inhibitor which was approved lately by USFDA for the treatment of metastatic non-small cell lung cancer (NSCLC). AFT was subjected to stress degradation studies under hydrolytic (acid, base and neutral), oxidative, thermal and photolytic conditions to investigate the inherent stability of the drug. The present study describes the simple and rapid HPLC method development for the selective separation of the AFT and its degradation products. The drug and degradation products were separated on Agilent Eclipse plus C18 (150 × 4.6 mm, 5 µ) column with ammonium acetate buffer (10 mM, pH 6.7) in gradient elution mode. The drug was found to be unstable in all the conditions studied. The developed chromatographic method was extended to tandem mass spectrometry (QTOF-MS) for the characterization of the degradation products. A total of 11 unknown degradation products were characterized using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS/MS). Two major degradation products (DP2 and DP3) were isolated using preparative HPLC and their structures were confirmed by conducting 1H and 13C NMR experiments. The isolated DPs were evaluated for their anticancer potential using non small cell lung cancer cell line A549. The IC50 values for AFT, DP2 and DP3 were found to be 15.02 ± 1.49, 25.00 ± 1.26 and 32.56 ± 0.11 respectively. The in silico toxicity studies were performed employing ProTox-II software for the assessment of toxicity potential of drug and its degradation products. Finally, the developed chromatographic method was validated as per the International Conference on Harmonization guideline Q2 (R1).