Identification and characterization of etomidate and metomidate metabolites in zebrafish, HLMs and S9 fraction by quadrupole-orbitrap LC-MS/MS for drug control.

Etomidate is a common non-barbiturate anesthetic with psychoactivity, and metomidate, a structural modifier of etomidate, also has the same psychoactive effect, and the abuse of both has gradually intensified. In this study, etomidate, metomidate and their metabolic profiles with 4 days postfertilization (4dpf) zebrafish, 4 months postfertilization (4mpf) zebrafish, human liver microsomes (HLMs) and human liver S9 fraction were investigated using Liquid chromatography with high resolution mass spectrometry (LC-HRMS) for the first time. 14 etomidate metabolites and 11 metomidate metabolites were found, and the related metabolic pathways included monohydroxylation, dihydroxylation, dehydrogenation, N-dealkylation, O-dealkylation, oxidation, N-glucuronidation, O-glucuronidation and combination. Etomidate acid (E6 and M6) was considered a common biomarker for monitoring the abuse of etomidate and its analogues. Two characteristic metabolites (E4 and M4) could be used as biomarkers to monitor etomidate or metomidate abuse, respectively. Dealkylation, hydroxylation and glucuronidation were the main metabolic pathways of etomidate and metomidate. The differences in metabolic profiles of the three metabolic models were also compared for the first time. The results of this study can provide important reference for the detection of target compounds against the abuse of etomidate and metomidate, and the metabolic analysis of similar substances.