First developed in the 1950s, benzodiazepines such as diazepam (Valium) and alprazolam (Xanax) are one of the most important groups of medicines that specifically produce sedation and sleep (Sternbach, 1978; EMCDDA, 2021b). They are the most widely prescribed group of medicines in the world, and are used to treat anxiety, insomnia, epilepsy and alcohol withdrawal. However, there is a high risk of abuse, and they can rapidly cause tolerance and dependence. This can lead to severe, and sometimes life-threatening, withdrawal symptoms. Because of this public health risk, there are often strict restrictions on prescribing them.

Given the high demand for commonly prescribed benzodiazepines, they are a major target for criminal groups that divert legitimate products from the market, sell unlicensed products or make fake versions of legitimate medicines. In the latter case, this includes using both controlled and new benzodiazepines and, potentially, other unrelated substances. Fake diazepam and alprazolam tablets are particularly common. Information about the market for new benzodiazepines in Europe, including supply chains, is limited. However, an important source of fake medicines containing these substances appears to be vendors on darknet markets and the surface web.

Many new benzodiazepines are potent substances (EMCDDA, 2021b; El Balkhi, 2020). The dose used in fake medicines can also be significantly higher than those used in legitimate licensed medicines. Increasingly, new benzodiazepines are involved in acute poisonings and deaths, particularly in parts of northern Europe (Essink et al., 2022; Kriikku et al., 2020; Rice et al., 2021), where many of the deaths linked to new benzodiazepines involve high-risk drug users who also use opioids and other central nervous system depressants (Kriikku et al., 2020; Rice et al., 2021; McAuley, 2022). Of note, the imposition of restrictions on prescribing benzodiazepine medicines over concerns of their abuse has been associated with an increase in the availability and use of new benzodiazepines in some places, including Scotland (the United Kingdom) and the United States (McAuley, 2022).

New benzodiazepines are also sold as substances in their own right for recreational use, to enhance or prolong the effects of other drugs (such as opioids), and to self-medicate (EMCDDA, 2021b). In a similar way to synthetic cannabinoids, new benzodiazepines infused into paper and clothing can be smuggled into prisons, and cases have been reported in the United Kingdom. This poses a high risk of overdose and, given the popularity of benzodiazepines in prisons in Europe, requires active surveillance (Daly, 2022; Ford et al., 2018).