From the curb to the curve: population exposure to the synthetic cannabinoid receptor agonist MDMB-4en-PINACA in Mayotte

The impact of changes in UK classification of the synthetic cannabinoid receptor agonists in ‘Spice’

Introduction Cannabis is the most common recreational drug worldwide and synthetic cannabinoid receptor agonists are currently the largest group of new psychoactive substances. The aim of this study was to compare the clinical features and outcomes of lone acute cannabis toxicity with lone acute synthetic cannabinoid receptor agonist toxicity in a large series of presentations to European emergency departments between 2013-2020. Methods Self-reported drug exposure, clinical, and outcome data were extracted from the European Drug Emergencies Network Plus which is a surveillance network that records data on drug-related emergency department presentations to 36 centres in 24 European countries. Cannabis exposure was considered the control in all analyses. To compare the lone cannabis and lone synthetic cannabinoid receptor agonist groups, univariate analysis using chi squared testing was used for categorical variables and non-parametric Mann-Whitney U- testing for continuous variables. Statistical significance was defined as a P value of <0.05. Results Between 2013-2020 there were 54,314 drug related presentations of which 2,657 were lone cannabis exposures and 503 lone synthetic cannabinoid receptor agonist exposures. Synthetic cannabinoid receptor agonist presentations had statistically significantly higher rates of drowsiness, coma, agitation, seizures and bradycardia at the time of presentation. Cannabis presentations were significantly more likely to have palpitations, chest pain, hypertension, tachycardia, anxiety, vomiting and headache. Discussion Emergency department presentations involving lone synthetic cannabinoid receptor agonist exposures were more likely to have neuropsychiatric features and be admitted to a psychiatric ward, and lone cannabis exposures were more likely to have cardiovascular features. Previous studies have shown variability in the acute toxicity of synthetic cannabinoid receptor agonists compared with cannabis but there is little comparative data available on lone exposures. There is limited direct comparison in the current literature between lone synthetic cannabinoid receptor agonist and lone cannabis exposure, with only two previous poison centre series and two clinical series. Whilst this study is limited by self-report being used to identify the drug(s) involved in the presentations, previous studies have demonstrated that self-report is reliable in emergency department presentations with acute drug toxicity. Conclusion This study directly compares presentations with acute drug toxicity related to the lone use of cannabis or synthetic cannabinoid receptor agonists. It supports previous findings of increased neuropsychiatric toxicity from synthetic cannabinoid receptor agonists compared to cannabis and provides further data on cardiovascular toxicity in lone cannabis use.

Introduction: The emergence of novel psychoactive substances has changed the epidemiology of drugs used recreationally throughout Europe and have posed significant challenges for clinicians, researchers and regulators. Synthetic cannabinoid receptor agonists have made up a large proportion of these novel psychoactive substances. Developed for legitimate scientific research, synthetic cannabinoid receptor agonists are potent agonists at CB1 and CB2 receptors and there have been many case reports of severe or fatal toxicity following their recreational use. At least 180 analytically confirmed compounds belonging to this group of drugs have been reported in Europe as of January 2019. Synthetic cannabinoid receptor agonists have a complex molecular structure, consisting of four pharmacophore components termed the ‘core’, ‘tail’, ‘linker’ and ‘linked’ groups. This structural complexity offers multiple opportunities for chemical modification to evade drug control legislation based on chemical structure, and this explains the large numbers of individual products that have been detected.Objectives: To discuss the chemical structure of synthetic cannabinoid receptor agonists and to describe the different nomenclature used to identify individual compounds thereby increasing understanding of their chemical heterogenicity and the potential relevance of their molecular structure to the risk of toxicity.Methods: The European Database on New Drugs (EDND) and EMCDDA-Europol annual implementation reports (2010–2017) was searched for compounds with known agonist activity at CB1 and/or CB2 receptors. Information on the different names and chemical structures of each compound was extracted and analysed for patterns. PUBMED, Google Scholar and MEDLINE databases were searched, in addition to non-peer reviewed sources, for data on structure, structure-activity relationships and nomenclatures for each compound.Nomenclature of synthetic cannabinoid receptor agonists: The structural complexity of synthetic cannabinoid receptor agonists presents challenges for nomenclature. There are several nomenclature systems in use.Colloquial and clandestine names: Non-scientific names (e.g. AKB-48, 2NEI, XLR-11) have been used to refer to specific compounds and most have probably been invented by vendors, presumably for the purpose of successful marketing of recreational products, however such names do not convey useful information about structure.Systematic chemical names: Each compound has a systematic chemical name that describes its exact structure; however, it is complex, unwieldy, inaccessible to non-chemists and not suitable for routine communication or clinical use.Serial names: Represent iterative designations assigned to compounds produced as a series in a laboratory (e.g. ‘WIN-‘, ‘HU-‘, ‘CP-‘, ‘JWH-‘ and ‘AM-‘). This nomenclature does not provide structural information or reflect structural similarities between compounds.Systematic abbreviated names: Succinctly describe each compound utilising structural pharmacophores. The chemical motif in each pharmacophore group is assigned a unique code-letter and assembled into a name with the format of ‘Linked Group – TailCoreLinker’. Frequently encountered groups include indole and indazole cores, amino-acid-like like groups, most notably methyl-3,3-dimethylbutanoate (MDMB), methanone linker groups and pentyl, 5-fluoropentyl and 4-fluorobenzyl tails. There has been inconsistent usage of this nomenclature, likely due to a lack of consensus and identification of code-letters for several chemical motifs.Emerging compounds and practices: Tricyclic carbazole and γ-carbolinone core analogues have been identified and may represent the next significant structural analogues to emerge onto the recreational market. There is a need to establish basic pharmacological and toxicological data for these analogues.Conclusions: There is a need for international consensus on the nomenclature used to name synthetic cannabinoid receptor agonists to ensure precise and effective communication between professional groups in the clinic and for the purposes of research and regulation, especially with the emergence of analogues of existing compounds and novel structural motifs. A well-defined nomenclature system also supports quick and accurate communication of the structure-activity of these compounds, potentially highlighting compounds that carry a significant risk of toxicity.

Synthetic cannabinoid receptor agonists (SCRAs) are one of the fastest growing classes of recreational drugs. Despite their growth in use, their vast chemical diversity and rapidly changing landscape of structures make understanding their effects challenging. In particular, the side effects for SCRA use are extremely diverse, but notably include severe outcomes such as cardiac arrest. These side effects appear at odds with the main putative mode of action, as full agonists of cannabinoid receptors. We have hypothesized that SCRAs may act as MAO inhibitors, owing to their structural similarity to known monoamine oxidase inhibitors (MAOI's) as well as matching clinical outcomes (hypertensive crisis) of ‘monoaminergic toxicity’ for users of MAOIs and some SCRA use. We have studied the potential for SCRA‐mediated inhibition of MAO‐A and MAO‐B via a range of SCRAs used commonly in the UK, as well as structural analogues to prove the atomistic determinants of inhibition. By combining in silico and experimental kinetic studies we demonstrate that SCRAs are MAO‐A‐specific inhibitors and their affinity can vary significantly between SCRAs, most notably affected by the nature of the SCRA ‘head’ group. Our data allow us to posit a putative mechanism of inhibition. Crucially our data demonstrate that SCRA activity is not limited to just cannabinoid receptor agonism and that alternative interactions might account for some of the diversity of the observed side effects and that these effects can be SCRA‐specific.

Context: Synthetic cannabinoid receptor agonists are the largest group of new psychoactive substances reported in the last decade; in this study we investigated how commonly these drugs are found in patients presenting to the Emergency Department with acute recreational drug toxicity.Methods: We conducted an observational cohort study enrolling consecutive adult patients presenting to an Emergency Department (ED) in London (UK) January–July 2015 (6 months) with acute recreational drug toxicity. Residual serum obtained from a serum sample taken as part of routine clinical care was analyzed using high-resolution accurate mass-spectrometry with liquid-chromatography (HRAM-LCMSMS). Minimum clinical data were obtained from ED medical records.Results: 18 (10%) of the 179 patient samples were positive for synthetic cannabinoid receptor agonists. The most common was 5F AKB-48 (13 samples, concentration 50–7600 pg/ml), followed by 5F PB-22 (7, 30–400 pg/mL), MDMB-CHMICA (7, 80–8000 pg/mL), AB-CHMINACA (3, 50–1800 pg/mL), Cumyl 5F-PINACA (1, 800 pg/mL) and BB-22 (1, 60 pg/mL). Only 9/18 (50%) in whom synthetic cannabinoid receptor agonists were detected self-reported synthetic cannabinoid receptor agonist use. The most common clinical features were seizures and agitation, both recorded in four (22%) individuals. Fourteen patients (78%) were discharged from the ED, one of the four admitted to hospital was admitted to critical care.Conclusions: Synthetic cannabinoid receptor agonists were found in 10% of this cohort with acute recreational drug toxicity but self-reported in only half of these. This suggests that presentations to the ED with acute synthetic cannabinoid receptor agonist toxicity may be more common than reported.

Functional evaluation of metabolites of synthetic cannabinoid receptor agonists

Study on the mass fragmentation pathway of the synthetic cannabinoids JWH-018 and JWH-073

IntroductionDespite decreasing consumption by general populations, use of synthetic cannabinoid receptor agonists (SCRAs) persists in some marginalised groups, including those who use other substances. This article explores SCRA consumption in an Australian cannabis treatment sample, comparing those who report ever using SCRAs with those who have never used SCRAs.MethodsA questionnaire orally administered in person to a convenience sample of 154 cannabis treatment service clients from New South Wales, Australia (71% male, median age 35) collected information regarding cannabis and SCRA use including motivations, effects and health-related consequences of use, demographics, other substance use and overall health. Demographic profiles and between-group differences were explored. McNemar tests compared effects of SCRA and cannabis. Logistic regression analysis determined predictors of SCRA use.ResultsHalf (53%) reported lifetime SCRA use; 20% reported previous-month use. The SCRA + cannabis group displayed greater polysubstance use and psychological distress. Reduced dependence on cannabis but higher levels of other substance use may predict SCRA use. Although curiosity motivated initial SCRA consumption, perceived psychoactive strength drove continued use. SCRAs appear to induce more negative side-effects than cannabis. Of the SCRA + cannabis group, 27% sought medical assistance for SCRA use. Most (90%) preferred cannabis to SCRAs, citing superior safety, effects and consistency of cannabis.ConclusionsAmong clients seeking treatment for cannabis use, SCRA use was relatively common, although not a preferred substance. Hazardous substance use and poor mental health characterised SCRA consumers, highlighting the need for continued monitoring by researchers and treatment providers of SCRA consumption in populations who use substances.

Cannabimimetic effects of abused indazole-carboxamide synthetic cannabinoid receptor agonists AB-PINACA, 5F-AB-PINACA and 5F-ADB-PINACA in mice: Tolerance, dependence and withdrawal

Indole- and indazole-based synthetic cannabinoid receptor agonists (SCRAs), featuring valine or tert-leucine substituents, are commonly abused new psychoactive substances (NPS). A major metabolic pathway for these SCRAs is hydrolysis of the terminal amide or methylester functionalities. Although these hydrolysis products were already detected as main ingredients in some "legal highs," these metabolites are often poorly characterized. Here, we report a systematic investigation of the activity of 7 common hydrolysis metabolites of 15 SCRAs featuring scaffolds based on L-valine or L-tert-leucine in direct comparison to their parent compounds. An activity-based cannabinoid receptor 1 (CB1 ) bio-assay was used for activity profiling of SCRAs and their metabolites in a stable HEK293T cell system. The recruitment of β-arrestin2 to the activated CB1 (each fused to one part of a split Nanoluciferase) was provoked by adding the (putative) SCRAs. Luminescence of the functionally complemented luciferase was monitored by a 96-well plate-reader. The major hydrolysis metabolites of 5F-AB-PINACA, ADB-CHMICA, ADB-CHMINACA, ADB-FUBICA, and their methyl- and ethylester derivatives showed no detectable CB1 activation at concentrations up to 1μM. On the other hand, metabolites of 5F-ADB-PINACA, AB-CHMINACA, and ADB-FUBINACA did retain activity, although significantly reduced as compared to the parent compounds (EC50 values >100nM). Activity-based characterization of SCRAs and their metabolites at CB1 may not only allow a better insight into the complex interplay between SCRAs and their metabolites in intoxications, but may also allow application of the concept of "activity equivalents" present in biological fluids or, alternatively, in confiscated materials.

Chapter 13 - Synthetic Cannabinoid Receptor Agonists

Synthetic cannabinoid receptor agonists exacerbate fentanyl-elicited respiratory depression and confer resistance to naloxone rescue in mice.

Signalling profiles of a structurally diverse panel of synthetic cannabinoid receptor agonists

The cannabinoid CB1 receptor (CB1) is a G protein-coupled receptor (GPCR) with widespread expression in the central nervous system. This canonically G⍺i/o-coupled receptor mediates the effects of Δ9-tetrahydrocannabinol (THC) and synthetic cannabinoid receptor agonists (SCRAs). Recreational use of SCRAs is associated with serious adverse health effects, making pharmacological research into these compounds a priority. Several studies have hypothesised that signalling bias may explain the different toxicological profiles between SCRAs and THC. Previous studies have focused on bias between G protein activation measured by cyclic adenosine monophosphate (cAMP) inhibition and β-arrestin translocation. In contrast, the current study characterises bias between G⍺ subtypes of the G⍺i/o family and β-arrestins; this method facilitates a more accurate assessment of ligand bias by assessing signals that have not undergone major amplification. We have characterised G protein dissociation and translocation of β-arrestin 1 and 2 using real-time BRET reporters. The responses produced by each SCRA across the G protein subtypes tested were consistent with the responses produced by the reference ligand AMB-FUBINACA. Ligand bias was probed by applying the operational analysis to determine biases within the G⍺i/o family, and between G protein subtypes and β-arrestins. Overall, these results confirm SCRAs to be balanced, high-efficacy ligands compared to the low efficacy ligand THC, with only one SCRA, 4CN-MPP-BUT7IACA, demonstrating statistically significant bias in one pathway comparison (towards β-arrestin 1 when compared with G⍺oA/oB). This suggests that the adverse effects caused by SCRAs are due to high potency and efficacy at CB1, rather than biased agonism.

Synthetic cannabinoid receptor agonists (SCRAs) are distributed on the drug market to produce THC-like effects while evading routine drug testing and legislation. The cyclobutylmethyl (CBM) and norbornylmethyl (NBM) side chain specifically circumvented the German legislation and led to the emergence of exploratory SCRAs in 2019-2021. The NBM SCRAs were detected post-amendment of the new psychoactive substances act in 2020, which scheduled all CBM SCRAs. All six SCRAs are full agonists at the cannabinoid receptor 1 compared with Δ9 -tetrahydrocannabinol and CP-55,940. The CBM SCRAs showed binding affinities of Ki : 29.4-0.65 nm and potencies of EC50 : 483-40.1nm (CBMICA << CBMINACA < CBMeGaClone). The norbornyl derivatives exhibited high affinities (Ki : 1.87-0.25 nm), with indazole being the most affine. Functional activity data confirmed that the indazole derivative tends to be the most potent of all three NBM SCRAs (EC50 : 169-1.78 nm). The sterically demanding NBM side chain increased the affinity and activity of almost all core structures. Future studies should be conducted on similarly voluminous side chain moieties. The 'life cycle' of all SCRAs on the drug market was less than a year. Notably, Cumyl-CBMICA was the most prevalent while also having the weakest cannabimimetic properties. Quantification of Cumyl-CBMICA during peak consumption in late 2019 and early 2020 revealed an increase in the concentration on the herbal material, which, together with forum entries and blog posts, corroborates the low in vitro cannabimimetic properties. Seizure prevalence data indicate that almost all SCRAs continue to be identified in 2022, potentially due to remaining stocks.