"Synthetic cathinones are related to the parent compound cathinone (Figure 1), one of the psychoactive principals in khat (Catha edulis Forsk). Cathinone derivatives are the β-keto (βk) analogues of a corresponding phenethylamine. The group includes several substances that have been used as active pharmaceutical ingredients (API) of medicinal products, e.g. amfepramone (diethylpropion; Figure 2). Since the mid-2000s, unregulated ring-substituted cathinone derivatives have appeared in the European recreational drugs market.
"The reasons for the more pronounced psychoactive effects and severe and fatal poisoning seen with synthetic cannabinoids are not particularly well understood, but at least two factors are likely to be important: the high potency of the substances and the unintentionally high doses that users are exposed to.
"Synthetic cannabinoids, also known as synthetic cannabinoid receptor agonists, are a group of drugs that mimic the effects of a substance found in cannabis called tetrahydrocannabinol (THC). THC is responsible for many of the psychoactive effects of cannabis which give that feeling of being ‘stoned’ or ‘high’ (Gaoni and Mechoulam, 1964; Huestis et al., 2001; Pertwee, 2005a; Pertwee, 2014). These effects are caused by activating a receptor in the brain called the cannabinoid receptor type 1 (CB1 receptor) (Huestis et al., 2001; Pertwee, 2014).
"Since around 2008, there has been a dramatic growth in the NPS market as globalisation and new technologies, such as the internet, have allowed them to be produced, sold and supplied on an industrial scale. Between 2009 and 2018, 119 countries and territories reported the emergence of 892 different NPS to UNODC, through the UNODC Early Warning Advisory on NPS (UNODC, 2019b). In Europe, more than 730 NPS have appeared on the drug market since monitoring began in 1997, with around 90 % of these being detected between 2008 and 2018 (EMCDDA, 2019b).
"In the operating guidelines on the early warning system, EMCDDA [European Monitoring Centre on Drugs and Drug Addiction] made it explicit that 'the term ‘new’ did not refer to newly invented, but rather ‘newly misused’' substances as 'most of the drugs in question were first created many years ago.'20 In fact, investigations into the potential use of piperazines as anthelmintic have been reported in scientific literature since the early 1950s.21 Yet they only started to emerge as a health problem in several countries in the decade 2001-2010.
"The findings on drug use are based partly on positive findings from urine tests and partly on reported use during the last 30 days. The levels are overall quite similar to 2012. A proportion of 10 per cent reported having used an illegal morphine substance during the past month, 33 per cent cannabis, 16 per cent stimulants and as many as 42 per cent benzodiazepines. This figure includes both prescribed and non-prescribed benzodiazepines. Twenty-five per cent of all patients report having been prescribed the drug by a doctor. In other words, the others must have used illegal sources.