Ethylbromazolam is a novel psychoactive substance (NPS) structurally similar to the known benzodiazepine Bromazolam. This ethyl analogue emerged on the illicit drug market in early 2025, with reports of detection in multiple countries throughout that year and more following in 2026. Much is known about Bromazolam in terms of its pharmacology and toxicology, however, there is limited availability of information around this new ethyl analogue. Ethylbromazolam has not been approved for medical use and its presence in counterfeit pharmaceuticals poses a health risk.

In this scientific poster, we report the study to identify probable phase I metabolites of the novel designer benzodiazepine Ethylbromazolam through incubation with human liver microsomes (HLMs) followed by liquid chromatography and high-resolution mass spectrometry analysis.

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To cite this poster: Layle, N., Bassman, J., Goodwin, S., et al. Understanding the Metabolism of Ethylbromazolam Using Human Liver Microsomes. Poster presented at: SOFT-TIAFT 2026 Joint Meeting; September 19 – 24, 2026; Chicago, IL.