Impact of 'street' benzodiazepines on drug-related deaths in England, Wales and Northern Ireland.

INTRODUCTION: 'Street' benzodiazepines (BZD) are structurally and pharmacologically related to BZDs licensed for human use. In this study we investigated how street BZDs contribute to overall BZD use and death prevalences in England, Wales and Northern Ireland. METHODS: Data were analysed from deaths reported to the National Programme on Substance Use Mortality with post-mortem BZD detections (1999-2021), BZDs seized from music festivals (2017-2021) and drug samples with BZD detections submitted to Welsh Emerging Drugs and Identification of Novel Substances (WEDINOS) (2017-2021). RESULTS: About 14,837 deaths with BZD detections were identified, with polydrug use evident in 99.3% of cases (n = 14,733/14,837). Deaths following BZD use increased by over 200% from 2010 (n = 556) to 2020 (n = 1245). Most BZD detections were of those available via NHS prescription (96.2%), although in most cases (61.9%) the BZD-majority diazepam (77.3% of detections)-had been illicitly sourced. While street BZD deaths represented only 8.5% of overall BZD deaths, street BZD deaths increased by over 1200% between 2015 (n = 26) and 2020 (n = 326). There were increasing proportions of street BZD deaths in each geographical region but was more marked in Northern Ireland. The proportion of individual BZDs seized at music festivals and submitted to WEDINOS largely reflected that of individual BZDs detected in deaths. DISCUSSION AND CONCLUSIONS: While deaths following street BZD use are increasing, most BZDs detected in deaths were prescribable BZDs that were often illicitly sourced. The types of BZD detected in post-mortem samples, festival seizures and WEDINOS submissions has evolved over time to reflect changes in BZD prevalence on the illicit drug market.