"The trend towards higher potency is likely most indicative of what to expect from future illicit substance market developments. According to Canadian drug seizure statistics heroin is no longer among the top ten recovered illegal substances [32, 40]. Fentanyl is currently the most-seized opioid but likely in the process of being replaced with even more potent synthetic opioids [10, 11]. This trend is exemplified by the fact that carfentanil is now being found more frequently than heroin during drug seizures [40]. Fentanyl’s evolutions to the drug of choice demonstrates how the market supply itself can define and change drug use patterns [10]. Although there is currently no clear indication of individuals specifically seeking and prioritising nitazenes or fentanyl-analogues over fentanyl, these substances have the potential of becoming the drug of choice in the near future. The transition to ultra-potent synthetic opioids could resemble the one that happened 5 years ago with fentanyl. That is, individuals who use opioids will be gradually exposed to these drugs, as the fentanyl sold will be cut, knowingly or unknowingly to the individuals using it [11, 45]. The exposure to these substances will likely lead to increased tolerance, and fentanyl alone may no longer provide the sought after physical and psychological effect it once did. This allows agents that are initially perceived to be contaminants to become to the drug of choice. Notably, a shift towards less potent and less dangerous substances has to date not been observed either in opioid markets or in other substance classes, making this development seem unidirectional and irreversible."


Meyer M, Westenberg JN, Jang KL, et al. Shifting drug markets in North America - a global crisis in the making?. Int J Ment Health Syst. 2023;17(1):36. Published 2023 Oct 25. doi:10.1186/s13033-023-00601-x