Characterization and tentative identification of new flunitrazepam metabolites in authentic human urine specimens using liquid chromatography ‐Q Extractive‐HF Hybrid Quadrupole‐Orbitrap‐mass spectrometry (LC‐QE‐HF‐MS)

AbstractFlunitrazepam (FNZ) is a potent hypnotic, sedative and amnestic drug used to treat severe insomnia. In our recent study, flunitrazepam (FNZ) metabolic profiles were investigated carefully. Six authentic human urine samples were purified using solid phase extraction (SPE) without enzymatic hydrolysis and urine extracts were then analyzed by liquid chromatography ‐Q Extractive‐HF Hybrid Quadrupole‐Orbitrap‐mass spectrometry (LC‐QE‐HF‐MS), using the full scan positive ion mode and targeted MS/MS (ddms2) technique to make accurate mass measurements. There were 25 metabolites, including 13 phase I and 12 phase II metabolites, which were detected a nd tentatively identified by LC‐QE‐HF‐MS. In addition, 9 previously unreported phase II glucuronide conjugates and 4 phase I metabolites are reported here for the first time. Eight metabolic pathways, including N‐ and O‐reduction, N‐glucuronidation, O‐glucuronidation, mono‐ and di‐ hydroxylation, demethylation, acetylation and combinations, were implicated in this work, and 2‐O‐reduction together with dihydroxylation were two novel metabolic pathways for FNZ that were identified tentatively. Although 7‐amino FNZ is widely considered to be the primary metabolite, a previo usly unreported metabolites (M12) can also serve as potential biomarkers for FNZ misuse.

Source: Journal of Mass Spectrometry - June 23, 2019 Category: Chemistry Authors: Shiyang Qin, Guobin Xin, Yuanfeng Wang, Jing Qiao, Wenfang Zhang, Duoqi Xu, Zizhen Xu, Yongtao Liu, Ying Zhang, Jianghai Lu Tags: RESEARCH ARTICLE Source Type: research