Identification of degradation products in flumazenil using LC-Q-TOF/MS and NMR: Degradation pathway elucidation

Flumazenil is an imidazobenzodiazepine derivative that antagonizes the actions of benzodiazepines. The degradation pathway elucidation plays an important role in the drug quality control. In this work, a reliable LC-Q-TOF/MS method was developed to separate and identify the degradation products of flumazenil generated in the stress testing conducted according to the ICH Q1A(R2) guideline. Fifteen degradation products were detected in total including three reported impurities and twelve unknown impurities. Based on the chromatographic and mass spectrometric data acquired, the structures of all the degradation products were identified. Besides, two major degradants were synthetized and further confirmed by NMR. The degradation pathways of flumazenil were elucidated, and the degradation characteristics of benzodiazepines were also discussed. The obtained results are of both great importance for the quality control of flumazenil and good reference for the degradation study of other benzodiazepines.