Designer benzodiazepines: Availability, motives, and fatalities. A systematic narrative review of human studies

Background: Studies on illegal drug use often include the use of regular benzodiazepines (BZDs), i.e., BZDs of pharmaceutical quality, obtained either via diversion or prescription. However, since two decades, designer benzodiazepines (DBZDs) are emerging on the illicit drug markets. DBZDs are generally illegally produced, short-acting, highly potent, cheap benzodiazepines that are easy available on street markets or the internet. In this systematic review we describe the availability, motives and fatalities related to DBZDs. Method: Systematic narrative review of 109 eligible studies, including 37 studies on availability, 29 studies on motives, and 56 studies on drug related deaths. Results: In many countries the prevalence of DBZDs on the illegal drug market is increasing. (D)BZDs are particularly popular among users of opioids, because they intensify and/or prolong the euphoric effect of opioids. In addition, patients on opioid agonist treatment (OAT) may use benzodiazepines to self-medicate withdrawal symptoms, anxiety and/or poor sleep quality. Although (D)BZDs are safe drugs when used alone, concurrent use of benzodiazepines and opioids is extremely dangerous, because it may lead to fatal overdoses, especially when illegally manufactured fentanyls (IMFs) are polluted with DBZDs. Discussion: In some countries, the concurrent use of (D)BZDs and opioids has resulted in many overdose deaths. Meanwhile, clinical guidelines recommend reluctance to prescribe benzodiazepines to people who use drugs, including those in OAT. However, such measures seem to facilitate the DBZD market as an unintended side-effect. Increasing OAT-availability with drug use counselling and monitoring together with take-home naloxone kits should, therefore, be considered.