Benzodiazepines are often used with other drugs like opioids, potentially leading to severe intoxications. Bretazenil, an imidazo-tetrahydropyrrolo-1,4-benzodiazepine, developed in the 1980s but never marketed as a medicine, has recently appeared on the illicit drug market. Given its high potency, short elimination half-life, and potential for rapid metabolism, it is essential to identify markers for bretazenil consumption for...