First case of drug-facilitated sexual assault involving metizolam.

Designer benzodiazepines (DBZD) have emerged on the illicit market over the past decade, raising growing toxicological and forensic concerns. Metizolam, a desmethyl analogue of etizolam, is one such compound with potent sedative and amnestic properties. To our knowledge, we report here the first documented case of drug-facilitated sexual assault (DFSA) involving metizolam. A 16-year-old female with no prior medical or substance use history was examined 21 h after awakening with amnesia and signs consistent with sexual assault. Toxicological analyses were performed using gas and liquid chromatography coupled with tandem mass spectrometry (GC-MS and LC-MS/MS). No psychotropic substances or alcohol were detected in blood. In hydrolysed urine, metizolam was identified at a concentration of 11 ng/mL, together with metoclopramide (0.2 ng/mL) and ethyl glucuronide (> 20 µg/mL), confirming recent alcohol consumption. GHB levels in blood and urine were within endogenous ranges. Metizolam was not detected in hair sampled simultaneously with blood and urine, supporting a single, recent intake around the time of the incident. The co-administration of alcohol and benzodiazepines can potentiate central nervous system depression and amnesia, increasing vulnerability to assault. This case illustrates the analytical challenges associated with detecting designer benzodiazepines in DFSA, due to their low concentrations, short half-lives, and frequent absence from routine screening panels. Advanced techniques such as LC-MS/MS or LC-HRMS are essential for their detection and identification. Continuous monitoring of emerging benzodiazepines and the publication of analytical case data are crucial to improving forensic awareness and the medico-legal management of victims.