Characteristics and time course of benzodiazepine-type new psychoactive substance detections in Australia: results from the Emerging Drugs Network of Australia - Victoria project 2020-2022

: The emergence of benzodiazepine-type new psychoactive substances (NPSs) are a growing international public health concern, with increasing detections in drug seizures and clinical and coronial casework. This study describes the patterns and nature of benzodiazepine-type NPS detections extracted from the Emerging Drugs Network of Australia – Victoria (EDNAV), to better characterise benzodiazepine-type NPS exposures within an Australian context. : EDNAV is a state-wide illicit drug toxicosurveillance project collecting data from patients presenting to an emergency department with illicit drug-related toxicity. Patient blood samples were screened for illicit, pharmaceutical and NPS utilising liquid chromatography-tandem mass spectrometry. Demographic, clinical, and analytical data was extracted from the centralised registry for cases with an analytical confirmation of a benzodiazepine-type NPS(s) between September 2020 – August 2022. : A benzodiazepine-type NPS was detected in 16.5% of the EDNAV cohort (n=183/1112). Benzodiazepine-type NPS positive patients were predominately male (69%, n=127), with a median age of 24 (range 16-68) years. Twelve different benzodiazepine-type NPSs were detected over the two-year period, most commonly clonazolam (n=82, 44.8%), etizolam (n=62, 33.9%), clobromazolam (n=43, 23.5%), flualprazolam (n=42, 23.0%), and phenazepam (n=31, 16.9%). Two or more benzodiazepine-type NPSs were detected in 47% of benzodiazepine-type NPS positive patients. No patient referenced the use of a benzodiazepine-type NPS by name or reported the possibility of heterogenous product content. : Non-prescription benzodiazepine-type NPS use may be an emerging concern in Australia, particularly amongst young males. The large variety of benzodiazepine-type NPS combinations suggest that consumers may not be aware of product heterogeneity upon purchase or use. Continued monitoring efforts are paramount to inform harm reduction opportunities.