Global emergence and γ-aminobutyric acid type A (GABAA) receptor activity of the new designer benzodiazepine ethylbromazolam
Caitlyn Norman, Dean Acreman, Meera Bissram, Blake Curtis, Sebastian Hamer, Folker Westphal, Michael Pütz, Cristiana Stefan, Sarah Delaney, Rick Lines, Malcolm D. Mcleod, Karen Mcdonald, Henrik Green
Archives of Toxicology May 20, 2026 DOI: 10.1007/s00204-026-04433-9 via OpenAlex
Summary
Ethylbromazolam, a new designer benzodiazepine, has emerged in Canada, the UK, Australia, and Germany, with increasing detections since November 2024 and a concurrent decrease in bromazolam detections, likely due to bromazolam's international control on December 3, 2024. Other designer benzodiazepines like desalkylgidazepam and clobromazolam have also increased. In vitro patch clamp assays show ethylbromazolam has similar activity at the GABA-A receptor as bromazolam, with EC50 values of 10.1 nM and 15.2 nM respectively, indicating comparable pharmacological activity and potential harm. Ongoing market monitoring is recommended.
Study at a glance
| Characteristics | Laboratory study with drug surveillance Peer reviewed |
|---|---|
| Keywords | Benzodiazepine Designer drug In vitro toxicology Medical prescription Pharmacology |
| Key finding | Ethylbromazolam has similar in vitro GABA-A receptor activity to bromazolam, with EC50 values of 10.1 nM and 15.2 nM respectively, and its emergence appears linked to bromazolam's international control. |
Abstract
Abstract Designer benzodiazepines (DBZDs) are a class of new psychoactive substances (NPS) designed as legal alternatives to prescription BZDs. Bromazolam has been the most prevalent DBZD detected on the recreational market around the world; however, a new DBZD, ethylbromazolam (8-bromo-1-ethyl-6-phenyl-4 H-[1,2,4]triazolo[4,3-a][1,4]benzodiazepine; also known as bromoethylazolam) has recently emerged. In this study, the emergence of ethylbromazolam in Canada, the UK, and Australia is reported based on analysis of samples from drug checking services and in Germany based on analysis of samples seized by customs and mail services. Since November 2024, ethylbromazolam has been increasingly detected with a concurrent decrease in bromazolam detections, suggesting that its emergence is likely in response to the international control of bromazolam on 3rd December 2024. Additionally, increased detections of other DBZDs, including desalkylgidazepam (bromonordiazepam) and clobromazolam (phenazolam) have been recently observed. The in vitro α 1 β 2 γ 2 GABA A receptor activity of ethylbromazolam was determined using an automated patch clamp assay. Ethylbromazolam was found to have similar in vitro GABA A receptor activity as bromazolam (EC 50 of 10.1 nM and 15.2 nM, respectively), indicating comparable pharmacological activity and potential for harm. The market should continue to be monitored closely as it continues to evolve in response to the control of bromazolam.