Identifying cytochrome P450s involved in oxidative metabolism of synthetic cannabinoid N-(adamantan-1-yl)-1-(5-fluoropentyl)-1H-indole-3-carboxamide (STS-135)

Identification of phase-I and phase-II metabolites and the metabolic pathway of the novel synthetic cannabinoid 5F-EDMB-PICA in vitro

5F-EDMB-PICA is a newly emerged synthetic cannabinoid which has been characterized in relevant literature in recent years. Although phase-I metabolites of 5F-EDMB-PICA have been partly reported, the phase-II metabolism of this synthetic cannabinoid has not been studied yet. In this study, we established a phase-I and phase-II metabolism model in vitro by using pooled human liver microsomes, NADPH regeneration system, and UGT incubation system, with 1 mg/ml 5F-EDMB-PICA added and incubated at 37 °C for 60 min. The metabolites were analyzed by Q Exactive™ Hybrid Quadrupole-Orbitrap™ Mass Spectrometer, via which we discovered and identified 14 phase-I metabolites and 4 phase-II metabolites of 5F-EDMB-PICA, involving pathways such as ester hydrolysis, dehydrogenation, hydrolytic defluorination, hydroxylation, dihydroxylation, glucuronidation, and combinations of the pathways mentioned above. We recommend considering the monohydroxylation metabolites (M9, M10) with higher content and intact ester and 5-fluoropentyl structures as potential biomarkers of 5F-EDMB-PICA.

Potential neonatal toxicity of new psychoactive substances

Cannabis, cocaine, 3,4-methylenedioxymethamphetamine, and lysergic acid diethylamide are psychoactive substances with a significant increase in consumption during the 21st century due to their popularity in medicinal and recreational use. New psychoactive substances (NPSs) mimic established psychoactive substances. NPSs are known as being natural and safe to consumers; however, they are neither natural nor safe, causing severe adverse reactions, including seizures, nephrotoxicity, and sometimes death. Synthetic cannabinoids, synthetic cathinones, phenethylamines, and piperazines are all examples of NPSs. As of January 2020, nearly 1000 NPSs have become documented. Due to their low cost, ease of availability, and difficulty of detection, misuse of NPSs has become a familiar and growing problem, especially in adolescents and young adults in the past decade. The use of NPSs is associated with higher risks of unplanned sexual intercourse and pregnancy. As many as 4 in 100 women seeking treatment for substance abuse are pregnant or nursing. Animal studies and human clinical case reports have shown that exposure to certain NPSs during lactation periods has toxic effects on neonates, increasing various risks, including brain damage. Nevertheless, neonatal toxicity effects of NPSs are usually unrecognized and overlooked by healthcare professionals. In this review article, we introduce and discuss the potential neonatal toxicity of NPSs, emphasizing synthetic cannabinoids. Utilizing the established prediction models, we identify synthetic cannabinoids and their highly accumulative metabolites in breast milk.

Characterisation of AMB-FUBINACA metabolism and CB1-mediated activity of its acid metabolite

PURPOSE

AMB-FUBINACA is a synthetic cannabinoid receptor agonist (SCRA) which is primarily metabolised by hepatic enzymes producing AMB-FUBINACA carboxylic acid. The metabolising enzymes associated with this biotransformation remain unknown. This study aimed to determine if AMB-FUBINACA metabolism could be reduced in the presence of carboxylesterase (CES) inhibitors and recreational drugs commonly consumed with it. The affinity and activity of the AMB-FUBINACA acid metabolite at the cannabinoid type-1 receptor (CB₁) was investigated to determine the activity of the metabolite.

METHODS

The effect of CES1 and CES2 inhibitors, and delta-9-tetrahydrocannabinol (Δ⁹-THC) on AMB-FUBINACA metabolism were determined using both human liver microsomes (HLM) and recombinant carboxylesterases. Radioligand binding and cAMP assays comparing AMB-FUBINACA and AMB-FUBINACA acid were carried out in HEK293 cells expressing human CB₁.

RESULTS

AMB-FUBINACA was rapidly metabolised by HLM in the presence and absence of NADPH. Additionally, CES1 and CES2 inhibitors both significantly reduced AMB-FUBINACA metabolism. Furthermore, digitonin (100 µM) significantly inhibited CES1-mediated metabolism of AMB-FUBINACA by ~ 56%, while the effects elicited by Δ⁹-THC were not statistically significant. AMB-FUBINACA acid produced only 26% radioligand displacement consistent with low affinity binding. In cAMP assays, the potency of AMB-FUBINACA was ~ 3000-fold greater at CB₁ as compared to the acid metabolite.

CONCLUSIONS

CES1A1 was identified as the main hepatic enzyme responsible for the metabolism of AMB-FUBINACA to its less potent carboxylic acid metabolite. This biotransformation was significantly inhibited by digitonin. Since other xenobiotics may also inhibit similar SCRA metabolic pathways, understanding these interactions may elucidate why some users experience high levels of harm following SCRA use.

Synthetic Cannabinoid-Related Deaths in England, 2012-2019

Aim: To identify drug-related death trends associated with synthetic cannabinoid receptor agonists (SCRAs) reported to the National Programme on Substance Abuse Deaths (NPSAD) from England. Design: Case reports from NPSAD (England) where a SCRA was detected in post-mortem tissue(s) and/or implicated in the death were extracted, analyzed, and compared against non-SCRA-related deaths that occurred over the same time period (2012-2019). Findings: One hundred sixty-five death SCRA-related reports were extracted, with 18 different SCRAs detected. Following the first death in 2012, a subsequent sharp increase in reporting is evident. Acute SCRA use was the underlying cause of death in the majority of cases (75.8%) with cardiorespiratory complications the most frequently cited underlying physiological cause (13.4%). SCRA users were predominantly found dead (68.6%), with a large proportion of those witnessed becoming unresponsive described as suddenly collapsing (81.6%). Psychoactive polydrug use was detected in 90.3% of cases, with alcohol the most commonly co-detected (50.3%), followed by opioids (42.2%), benzodiazepines/Z-drugs (32.1%), stimulants (32.1%, [28.5% cocaine]), and cannabis (24.8%). Compared to all non-SCRA-related NPSAD deaths occurring over the same time period, SCRA-related decedents were more predominantly male (90.3% vs. 72.0%; p<0.01), and lived in more deprived areas (p<0.01). While a comparatively significant proportion of decedents were homeless (19.4% vs. 4.1%), living in a hostel (13.3% vs. 2.3%) or in prison (4.9% vs. 0.2%) at time of death (all p<0.01), the greatest majority of SCRA-related decedents were living in private residential accommodations (57.6%). Conclusions: This is the largest dataset regarding SCRA-related mortalities reported to date. Reporting of SCRA-related deaths in England have increased considerably, with polydrug use a specific concern. Lack of effective deterrents to SCRA use under current UK legislation, compounded by limited knowledge regarding the physiological impacts of SCRA consumption and their interaction with other co-administered substances are contributory factors to the occurrence of SCRA-related mortalities in an increasingly deprived demographic.