In vitro characterization of new psychoactive substances at the μ-opioid, CB1, 5HT1A, and 5-HT2A receptors—On-target receptor potency and efficacy, and off-target effects
Forensic Science International October 23, 2020 Anna Åstrand, Davide Guerrieri, Svante Vikingsson et al. 21 citations
Sixty new psychoactive substances (NPS) and their metabolites, including opioids, cannabinoids, and serotonergic hallucinogens, were screened for their ability to activate μ-opioid, CB1, 5-HT1A, and 5-HT2A receptors. Most substances activated their intended target receptor. Among μ-opioid agonists, 2-fluorofentanyl (EC50 = 1.0 nM), carfentanil (EC50 = 2.7 nM), and acrylfentanyl (EC50 = 2.8 nM) were the most potent, with a >1500-fold potency range across compounds. Furanylfentanyl, 4-methoxybutyrylfentanyl, and valerylfentanyl acted as partial agonists. On the 5-HT2A receptor, bromo-dragonfly was the most potent (EC50 = 0.05 nM, 400 times more potent than LSD), followed by NBOMe compounds (EC50 0.11–1.3 nM). Off-target μ-opioid activation occurred for piperazines, phenethylamines, and tryptamines. The synthetic cannabinoid metabolite 3-carboxy indole PB-22 activated 5-HT2A. Bromo-dragonfly activated all four receptors. These findings highlight complex, often overlapping targets among NPS.