Nonmedical use of benzodiazepines and Z-drugs in the UK.

Aims: To estimate prevalence of last 12-month nonmedical use (NMU) of benzodiazepines and Z-drugs (the nonbenzodiazepine hypnotics zaleplon, zolpidem and zopiclone) in the UK.
Methods: Data were collected using the Non-Medical Use of Prescription Drugs survey with poststratification weighting applied to be representative of the UK population (≥16 years). Participants were questioned about whether they had nonmedically used benzodiazepines and/or Z-drugs in the last 12-months and from where they had obtained the drug (including via a prescription, or illicitly from a friend/family member, a dealer or via the internet). Additional questions were asked about last 12-month use of illicit drugs (cannabis, cocaine, 3,4-methylenedioxymethylamphetamine [MDMA], non-pharmaceutical amphetamine, crack cocaine and/or heroin).
Results: The study included 10 006 eligible participants representing approximately 52 927 000 UK adults. The estimated prevalence of past 12-month NMU of any benzodiazepine and/or Z-drug was 1.2% (95% confidence interval: 1.0-1.5) corresponding to approximately 635 000 adults; amongst this group only an estimated 4.6% (1.2-8.0) had NMU of both a benzodiazepine and a Z-drug. The highest prevalence of NMU for only Z-drugs was among those who had used heroin in the last 12-months (5.4%, 2.7-10.5), whilst the highest prevalence of NMU for only benzodiazepines was among those who had used illicit stimulants in the last 12-months: cocaine (5.9%, 3.8-8.9), amphetamine (5.6%, 3.1-10.0) and MDMA (5.2%, 3.1-8.8). The drug non-medically used was more commonly acquired without than with a prescription for both only benzodiazepines (70.2%, 59.4-81.1 compared to 51.3%, 41.5-64.6) and only Z-drugs (75.6%, 61.6-89.7 compared to 33.9%, 16.9-51.0).
Conclusion: There is little overlap between benzodiazepine and Z-drug NMU suggesting distinct nonmedical use of the drugs; future studies need to explore whether this relates to personal preference, drug availability or other factors. A significant proportion are acquiring these drugs for NMU without a prescription, so without guidance and monitoring from a medical practitioner. While the dangers of mixing benzodiazepines and heroin/other opioids are well documented, there is a paucity of data regarding concomitant NMU of benzodiazepines and stimulant drugs, or NMU of Z-drugs and opioids, and, given the prevalence of these combinations, this requires further investigation.
(© 2020 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)