Toxic by design? Formation of thermal degradants and cyanide from carboxamide-type synthetic cannabinoids CUMYL-PICA, 5F-CUMYL-PICA, AMB-FUBINACA, MDMB-FUBINACA, NNEI, and MN-18 during exposure to high temperatures

The impact of piperazine and antipsychotic co-exposures and CB1 blockade on the effects elicited by AMB-FUBINACA, a synthetic cannabinoid, in mice

BACKGROUND & PURPOSE

The constant emergence and broad toxicological effects of synthetic cannabinoids create a discernible public health threat. The synthetic cannabinoid AMB-FUBINACA (AMB-FUB) is a potent agonist at the CB1 receptor and has been associated with numerous fatalities. Synthetic cannabinoids are commonly abused alongside other drugs and medications, including a "party pill" drug, para-fluorophenylpiperazine (pFPP), and the antipsychotic risperidone. This research aimed to investigate the mechanisms underpinning AMB-FUB toxicity and the impact of clinically relevant co-exposures in vivo.

EXPERIMENTAL APPROACH

Male and female C57Bl/6 mice received a single dose of AMB-FUB (3 or 6 mg kg-1), pFPP (10 or 20 mg kg-1) or vehicle intraperitoneally. Mice were co-exposed to AMB-FUB (3 mg kg-1) and pFPP (10 mg kg-1) or risperidone (0.5 mg kg-1) to investigate these drug combinations. To study receptor-dependency and potential rescue of AMB-FUB toxicity, rimonabant (3 mg kg-1) was administered both pre- and post-AMB-FUB. Adverse effects caused by drug administration, including hypothermia and convulsions, were recorded.

KEY RESULTS

AMB-FUB induced CB1-dependent hypothermia and convulsions in mice. The combination of AMB-FUB and pFPP significantly potentiated hypothermia, as did risperidone pre-treatment. Interestingly, risperidone provided significant protection from AMB-FUB-induced convulsions in female mice. Pre- and post-treatment with rimonabant was able to significantly attenuate both hypothermia and convulsions in mice administered AMB-FUB.

CONCLUSION & IMPLICATIONS

Factors such as dose, CB1 signalling, and substance co-exposure significantly contribute to the toxicity of AMB-FUBINACA. Mechanistic understanding of synthetic cannabinoid toxicity and fatality can help inform overdose treatment strategies and identify vulnerable populations of synthetic cannabinoid users.

Investigating selectivity and bias for G protein subtypes and β-arrestins by synthetic cannabinoid receptor agonists at the cannabinoid CB1 receptor

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.

Evaluating signaling bias for synthetic cannabinoid receptor agonists at the cannabinoid CB2 receptor

The rapid structural evolution and emergence of novel synthetic cannabinoid receptor agonists (SCRAs) in the recreational market remains a key public health concern. Despite representing one of the largest classes of new psychoactive substances, pharmacological data on new SCRAs is limited, particularly at the cannabinoid CB2 receptor (CB2 ). Hence, the current study aimed to characterize the molecular pharmacology of a structurally diverse panel of SCRAs at CB2 , including 4-cyano MPP-BUT7AICA, 4F-MDMB-BUTINACA, AMB-FUBINACA, JWH-018, MDMB-4en-PINACA, and XLR-11. The activity of SCRAs was assessed in a battery of in vitro assays in CB2 -expressing HEK 293 cells: G protein activation (Gαi3 and GαoB ), phosphorylation of ERK1/2, and β-arrestin 1/2 translocation. The activity profiles of the ligands were further evaluated using the operational analysis to identify ligand bias. All SCRAs activated the CB2 signaling pathways in a concentration-dependent manner, although with varying potencies and efficacies. Despite the detection of numerous instances of statistically significant bias, compound activities generally appeared only subtly distinct in comparison with the reference ligand, CP55940. In contrast, the phytocannabinoid THC exhibited an activity profile distinct from the SCRAs; most notably in the translocation of β-arrestins. These findings demonstrate that CB2 is able to accommodate a structurally diverse array of SCRAs to generate canonical agonist activity. Further research is required to elucidate whether the activation of CB2 contributes to the toxicity of these compounds.

Indazole-derived synthetic cannabinoids: Absolute configuration determination and structure characterization by circular dichroism and DFT calculations

An increasing number of products containing synthetic cannabinoids pose a growing crisis to public health worldwide. Recently, a rising number of cases of serious adverse health effects, intoxications, and death cases associated with synthetic cannabinoids were reported. The current study represents the comprehensive structural analysis of three new synthetic cannabinoids (AB-, ADB- and AMB-FUBINACA) in solution investigated by electronic and vibrational circular dichroism together with the conventional methods of infrared and ultraviolet absorption spectroscopy, all supported by the density functional theory (DFT) calculations. The best level of theory to reproduce the experimental wavenumbers and wavelengths was found to be the B3PW91 method with a 6-311++G(d,p) basis set including the implicit solvent effect simulation. Very good agreement between the experimental and simulated spectra allowed us to determine the absolute configuration and a detailed interpretation of the IR absorption, VCD, ECD and UV spectra of AB-, ADB- and AMB-FUBINACA. In addition, the HOMO and LUMO electronic transitions were calculated.

The piperazine analogue para-fluorophenylpiperazine alters timing of the physiological effects of the synthetic cannabinoid receptor agonist AMB-FUBINACA, without changing its discriminative stimulus, signalling effects, or metabolism

AMB-FUBINACA is a synthetic cannabinoid receptor agonist (SCRA), which has been associated with substantial abuse and health harm since 2016 in many countries including New Zealand. A characteristic of AMB-FUBINACA use in New Zealand has included the observation that forensic samples (from autopsies) and drugs seized by police have often been found to contain para-fluorophenylpiperazine (pFPP), a relatively little-characterised piperazine analogue that has been suggested to act through 5HT1a serotonin receptors. In the current study, we aimed to characterise the interactions of these two agents in rat physiological endpoints using plethysmography and telemetry, and to examine whether pFPP altered the subjective effects of AMB-FUBINACA in mice trained to differentiate a cannabinoid (THC) from vehicle. Though pFPP did not alter the ability of AMB-FUBINACA to substitute for THC, it did appear to abate some of the physiological effects of AMB-FUBINACA in rats by delaying the onset of AMB-FUBINACA-mediated hypothermia and shortening duration of bradycardia. In HEK cells stably expressing the CB1 cannabinoid receptor, 5HT1a, or both CB1 and 5HT1a, cAMP signalling was recorded using a BRET biosensor (CAMYEL) to assess possible direct receptor interactions. Although low potency pFPP agonism at 5HT1a was confirmed, little evidence for signalling interactions was detected in these assays: additive or synergistic effects on potency or efficacy were not detected between pFPP and AMB-FUBINACA-mediated cAMP inhibition. Experiments utilising higher potency, classical 5HT1a ligands (agonist 8OH-DPAT and antagonist WAY100635) also failed to reveal evidence for mutual CB1/5HT1a interactions or cross-antagonism. Finally, the ability of pFPP to alter the metabolism of AMB-FUBINACA in rat and human liver microsomes into its primary carboxylic acid metabolite via carboxylesterase-1 was assessed by HPLC; no inhibition was detected. Overall, the effects we have observed do not suggest that increased harm/toxicity would result from the combination of pFPP and AMB-FUBINACA.

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.

Off-target pharmacological profiling of synthetic cannabinoid receptor agonists including AMB-FUBINACA, CUMYL-PINACA, PB-22, and XLR-11

INTRODUCTION

Synthetic cannabinoid receptor agonists (SCRAs) are a diverse class of new psychoactive substances that have been associated with multiple instances and types of toxicity. Some SCRAs appear to carry a greater toxicological burden than others, or compared to the prototypical cannabis-derived agonist Δ⁹-tetrahydrocannabinol (Δ⁹-THC), despite a common primary mechanism of action via cannabinoid 1 (CB1) receptors. "Off-target" (i.e., non-CB1 receptor) effects could underpin this differential toxicity, although there are limited data around the activity of SCRAs at such targets.

METHODS

A selection of 7 SCRAs (AMB-FUBINACA, XLR11, PB-22, AKB-48, AB-CHMINICA, CUMYL-PINACA, and 4F-MDMB-BUTINACA), representing several distinct chemotypes and toxicological profiles, underwent a 30 μM single-point screen against 241 G protein-coupled receptor (GPCR) targets in antagonist and agonist mode using a cellular β-arrestin recruitment assay. Strong screening "hits" at specific GPCRs were followed up in detail using concentration-response assays with AMB-FUBINACA, a SCRA with a particularly notable history of toxicological liability.

RESULTS

The single-point screen yielded few hits in agonist mode for any compound aside from CB1 and CB2 receptors, but many hits in antagonist mode, including a range of chemokine receptors, the oxytocin receptor, and histamine receptors. Concentration-response experiments showed that AMB-FUBINACA inhibited most off-targets only at the highest 30 μM concentration, with inhibition of only a small subset of targets, including H₁ histamine and α_2B adrenergic receptors, at lower concentrations (≥1 μM). AMB-FUBINACA also produced concentration-dependent CB1 receptor signaling disruption at concentrations higher than 1 μM, but did not produce overt cytotoxicity beyond CP55,940 or Δ⁹-THC in CB1 expressing cells.

DISCUSSION

These results suggest that while some "off-targets" could possibly contribute to the SCRA toxidrome, particularly at high concentrations, CB1-mediated cellular dysfunction provides support for hypotheses concerning on-target, rather than off-target, toxicity. Further investigation of non-GPCR off-targets is warranted.

The Spicy Story of Cannabimimetic Indoles

The Sterling Research Group identified pravadoline as an aminoalkylindole (AAI) non-steroidal anti-inflammatory pain reliever. As drug design progressed, the ability of AAI analogs to block prostaglandin synthesis diminished, and antinociceptive activity was found to result from action at the CB1 cannabinoid receptor, a G-protein-coupled receptor (GPCR) abundant in the brain. Several laboratories applied computational chemistry methods to ultimately conclude that AAI and cannabinoid ligands could overlap within a common binding pocket but that WIN55212-2 primarily utilized steric interactions via aromatic stacking, whereas cannabinoid ligands required some electrostatic interactions, particularly involving the CB1 helix-3 lysine. The Huffman laboratory identified strategies to establish CB2 receptor selectivity among cannabimimetic indoles to avoid their CB1-related adverse effects, thereby stimulating preclinical studies to explore their use as anti-hyperalgesic and anti-allodynic pharmacotherapies. Some AAI analogs activate novel GPCRs referred to as "Alkyl Indole" receptors, and some AAI analogs act at the colchicine-binding site on microtubules. The AAI compounds having the greatest potency to interact with the CB1 receptor have found their way into the market as "Spice" or "K2". The sale of these alleged "herbal products" evades FDA consumer protections for proper labeling and safety as a medicine, as well as DEA scheduling as compounds having no currently accepted medical use and a high potential for abuse. The distribution to the public of potent alkyl indole synthetic cannabimimetic chemicals without regard for consumer safety contrasts with the adherence to regulatory requirements for demonstration of safety that are routinely observed by ethical pharmaceutical companies that market medicines.

Quantification of Major Metabolites of AB-FUBINACA in Solid Tissues Obtained from an Abuser

AB-FUBINACA M3 was reported to be a major metabolite of the drug, but its in vivo concentration in authentic human solid tissues has not been quantified yet. Another metabolite AB-FUBINACA M4 did not receive much attention previously and also has not been quantified yet in any authentic human specimens. The aims of this study are to establish a sensitive method for quantification of M3 and M4 in solid tissues and to compare the metabolite profile of AB-FUBINACA in authentic human specimens in vivo with that produced by human hepatocytes in vitro. The quantification was performed by liquid chromatography (LC)-quadrupole-ion trap-tandem mass spectrometry (MS-MS), and the characterization by LC-quadrupole Orbitrap MS-MS The limits of quantification of M3 were 10 pg/mL and 60 pg/g, and those of M4 were 100 pg/mL and 600 pg/g in urine and tissues, respectively. In the present work, M3 and M4 were identified and quantified in human lung, liver and kidney obtained from a cadaver for the first time; the concentrations of M3 were 226, 255, 202 and 155 pg/mL or g, and those of M4 14,400, 768, 637 and 1,390 pg/mL or g in urine, lung, liver and kidney, respectively. The peak intensity profiles of seven metabolites in these specimens were compared with that produced by human hepatocytes; the top three metabolites in urine specimen were completely different from those of hepatocytes. M3 was reported as the predominant metabolite in several previous works and M4 was listed as a minor metabolite in only one work, but, in this work, M4 has been found to be the major metabolite in all of the authentic urine, lung, liver and kidney specimens. The M3 plus M4 metabolites in lung or kidney were found most recommendable to prove AB-FUBINACA consumption, when urine specimen is lacking.

Air monitoring for illegal drugs including new psychoactive substances: A review of trends, techniques and thermal degradation products

The detection of illicit psychotropic substances in both indoor and outdoor air is a challenging analytical discipline, and the data from such investigation may provide intelligence in a variety of fields. Applications of drug monitoring in air include providing data on national and international drug consumption trends, as monitored by organisations such as the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) and the United Nations Office on Drugs and Crime (UNODC). Air monitoring enables mapping of illicit drug manufacturing, dealing or consumption in cities and the identification of emergent compounds including the recent proliferation of new psychoactive substances (NPS). The rapid spread of NPS has changed the global drug market with greater diversity and dynamic spread of such compounds over several nations. This review provides an up to date analysis of key thematic areas within this analytical discipline. The process of how illicit psychotropic substances spread from emission sources to the atmosphere is considered alongside the sampling and analytical procedures involved. Applications of the technique applied globally are reviewed with studies ranging from the analysis of individual dwellings through to major international air-monitoring campaigns providing evidence on global drug trends. Finally, we consider thermal breakdown products of illicit psychotropic substances including NPS that are released upon heating, combustion or vaping and related potential for exposure to these compounds in the air.

Sex-dependent pharmacological profiles of the synthetic cannabinoid MMB-Fubinaca

Synthetic cannabinoids have emerged as novel psychoactive substances with damaging consequences for public health. They exhibit high affinity at the cannabinoid type-1 (CB₁ ) receptor and produce similar and often more potent effects as other CB₁ receptor agonists. However, we are still far from a complete pharmacological understanding of these compounds. In this study, by using behavioral, molecular, pharmacological, and electrophysiological approaches, we aimed at characterizing several in vitro and in vivo pharmacological effects of the synthetic cannabinoid MMB-Fubinaca (also known as AMB-Fubinaca or FUB-AMB), a particular synthetic cannabinoid. MMB-Fubinaca stimulates CB₁ receptor-mediated functional coupling to G-proteins in mouse and human brain preparations in a similar manner as the CB₁ receptor agonist WIN55,512-2 but with a much greater potency. Both drugs similarly activate the CB₁ receptor-dependent extracellular signal-regulated kinase (ERK) pathway. Notably, in vivo administration of MMB-Fubinaca in mice induced greater behavioral and electrophysiological effects in male than in female mice in a CB₁ receptor-dependent manner. Overall, these data provide a solid pharmacological profiling of the effects of MMB-Fubinaca and important information about the mechanisms of action underlying its harmful impact in humans. At the same time, they reinforce the significant sexual dimorphism of cannabinoid actions, which will have to be taken into account in future animal and clinical studies.

Overview of Synthetic Cannabinoids ADB-FUBINACA and AMB-FUBINACA: Clinical, Analytical, and Forensic Implications

ADB-FUBINACA and AMB-FUBINACA are two synthetic indazole-derived cannabinoid receptor agonists, up to 140- and 85-fold more potent, respectively, than trans-∆⁹-tetrahydrocannabinol (∆⁹-THC), the main psychoactive compound of cannabis. Synthesised in 2009 as a pharmaceutical drug candidate, the recreational use of ADB-FUBINACA was first reported in 2013 in Japan, with fatal cases being described in 2015. ADB-FUBINACA is one of the most apprehended and consumed synthetic cannabinoid (SC), following AMB-FUBINACA, which emerged in 2014 as a drug of abuse and has since been responsible for several intoxication and death outbreaks. Here, we critically review the physicochemical properties, detection methods, prevalence, biological effects, pharmacodynamics and pharmacokinetics of both drugs. When smoked, these SCs produce almost immediate effects (about 10 to 15 s after use) that last up to 60 min. They are rapidly and extensively metabolised, being the O-demethylated metabolite of AMB-FUBINACA, 2-(1-(4-fluorobenzyl)-1H-indazole-3-carboxamide)-3-methylbutanoic acid, the main excreted in urine, while for ADB-FUBINACA the main biomarkers are the hydroxdimethylpropyl ADB-FUBINACA, hydroxydehydrodimethylpropyl ADB-FUBINACA and hydroxylindazole ADB-FUBINACA. ADB-FUBINACA and AMB-FUBINACA display full agonism of the CB1 receptor, this being responsible for their cardiovascular and neurological effects (e.g., altered perception, agitation, anxiety, paranoia, hallucinations, loss of consciousness and memory, chest pain, hypertension, tachycardia, seizures). This review highlights the urgent requirement for additional studies on the toxicokinetic properties of AMB-FUBINACA and ADB-FUBINACA, as this is imperative to improve the methods for detecting and quantifying these drugs and to determine the best exposure markers in the various biological matrices. Furthermore, it stresses the need for clinicians and pathologists involved in the management of these intoxications to describe their findings in the scientific literature, thus assisting in the risk assessment and treatment of the harmful effects of these drugs in future medical and forensic investigations.

Metabolic profiling of synthetic cannabinoid 5F-ADB and identification of metabolites in authentic human blood samples via human liver microsome incubation and ultra-high-performance liquid chromatography/high-resolution mass spectrometry

RATIONALE

Indazole carboxamide synthetic cannabinoids, a prevalent class of recreational drugs, are a major clinical, forensic and public health challenge. One such compound, 5F-ADB, has been implicated in fatalities worldwide. Understanding its metabolism and distribution facilitates the development of laboratory assays to substantiate its consumption. Synthetic cannabinoid metabolites have been extensively studied in urine; studies identifying metabolites in blood are limited and no data on the metabolic stability (half-life, clearance and extraction ratio) of 5F-ADB have been published prior to this report.

METHODS

The in vitro metabolism of 5F-ADB was elucidated via incubation with human liver microsomes for 2 h at 37°C. Samples were collected at multiple time points to determine its metabolic stability. Upon identification of metabolites, authentic forensic human blood samples underwent liquid-liquid extraction and were screened for metabolites. Extracts were analyzed via ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/QTOFMS) operated in positive electrospray ionization mode.

RESULTS

Seven metabolites were identified including oxidative defluorination (M1); carboxypentyl (M2); monohydroxylation of the fluoropentyl chain (M3.1/M3.2) and indazole ring system (M4); ester hydrolysis (M5); and ester hydrolysis with oxidative defluorination (M6). The half-life (3.1 min), intrinsic clearance (256.2 mL min^-1  kg^-1 ), hepatic clearance (18.6 mL min^-1 kg^-1 ) and extraction ratio (0.93) were determined for the first time. In blood, M1 was present in each sample as the most abundant substance; two samples contained M5; one contained 5F-ADB, M1 and M5.

CONCLUSIONS

5F-ADB is rapidly metabolized in HLM. 5F-ADB, M1 and M5 are pharmacologically active at the cannabinoid receptors (CB₁ /CB₂ ) and M1 and M5 may contribute to a user's impairment profile. The results demonstrate that it is imperative that synthetic cannabinoid assays screen for pharmacologically active metabolites, especially for drugs with short half-lives. The authors propose that M1 and M5 are appropriate markers to include in laboratory blood tests screening for 5F-ADB.

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Designer drugs: a medicinal chemistry perspective (II)

During 2012-2018, the clandestine manufacture of new psychoactive substances (NPS) designed to circumvent substance control regulations increased exponentially worldwide, with concomitant increase in fatalities. This review focuses on three compound classes identified as synthetic opioids, synthetic amphetamines, and synthetic cannabinoids and highlights the medicinal chemistry precedents utilized by clandestine laboratories to develop new NPS with increased brain penetration, longer duration of action, and greater potency. Chemical approaches to illicit drug abuse treatment options, particularly for opioid use disorder, are also discussed.

Four cases of death involving the novel synthetic cannabinoid 5F-Cumyl-PEGACLONE

Purpose

Cumyl-PEGACLONE was the first synthetic cannabinoid (SC) with a γ-carbolinone core structure detected in forensic casework and, since then, it has dominated the German SC-market. Here the first four cases of death involving its fluorinated analog, 5F-Cumyl-PEGACLONE, a recently emerged γ-carbolinone derived SC, are reported.

Methods

Complete postmortem examinations were performed. Postmortem samples were screened by immunoassay, gas chromatography mass spectrometry (GC–MS) or liquid chromatography tandem mass spectrometry. For quantification of SCs, the standard addition method was employed. Herbal blends were analyzed by GC–MS. In each case of death, the Toxicological Significance Score (TSS) was assigned to the compound.

Results

5F-Cumyl-PEGACLONE was identified at concentrations ranging 0.09–0.45 ng/mL in postmortem femoral blood. In case 1, signs of hypothermia and kidney bleedings were noted. Despite a possible tolerance due to long term SC use, a TSS of 3 was assigned. In case 2, an acute heroin intoxication occurred and a contributory role (TSS = 1) of 5F-Cumyl-PEGACLONE was suggested. In case 3, a prisoner was found dead. GC–MS analysis of herbal blends, retrieved in his cell together with paraphernalia, confirmed the presence of 5F-Cumyl-PEGACLONE and a causative role was deemed probable (TSS = 2). In case 4, the aspiration of gastric content due to a SC-induced coma was observed (TSS = 3).

Conclusions

5F-Cumyl-PEGACLONE is an emerging and extremely potent SC which raises serious public health concerns. A comprehensive analysis of circumstantial, clinical, and postmortem findings, as well as an in-depth toxicological analysis is necessary for a valid interpretation and for the assessment of the toxicological significance.

The phenomenon of para-Fluorophenylpiperazine (pFPP) in combination with the synthetic cannabinoid AMB-FUBINACA in seized plant material in New Zealand

New psychoactive substances have emerged as a vast and diverse group of illicit drugs over the past decade, with synthetic cannabinoids comprising the largest of the categories. Commonly, a single synthetic cannabinoid is applied to plant material, creating a product that is designed to be smoked by the user. The clandestine preparation process can result in an unevenly distributed product, with varying concentration within and between plant materials. This investigation describes the novel co-detection of the synthetic cannabinoid AMB-FUBINACA, with the piperazine para-fluorophenylpiperazine (pFPP), in a number of plant material samples analysed in New Zealand in 2017. Of 157 samples of plant material containing AMB-FUBINACA, pFPP was detected in 55 of them. A range of pFPP concentrations was observed between the plant material samples, as well as intra-batch variation. The presence of both drugs may be designed to enhance, prolong or balance the psychoactive effects caused from smoking the plant material. However the intended purpose has not been verified. This is the first reported combination of a synthetic cannabinoid and a piperazine in plant material.

Enantiospecific Synthesis, Chiral Separation, and Biological Activity of Four Indazole-3-Carboxamide-Type Synthetic Cannabinoid Receptor Agonists and Their Detection in Seized Drug Samples

Synthetic cannabinoid receptor agonists (SCRAs) have been the largest group of illicit psychoactive substances reported to international monitoring and early warning systems for many years. Carboxamide-type SCRAs are amongst the most prevalent and potent. Enantiospecific synthesis and characterization of four indazole-3-carboxamides, AMB-FUBINACA, AB-FUBINACA, 5F-MDMB-PINACA (5F-ADB), and AB-CHMINACA is reported. The interactions of the compounds with CB1 and CB2 receptors were investigated using a G-protein coupled receptor (GPCR) activation assay based on functional complementation of a split NanoLuc luciferase and EC50 (a measure of potency) and Emax (a measure of efficacy) values determined. All compounds demonstrated higher potency at the CB2 receptor than at the CB1 receptor and (S)-enantiomers had an enhanced potency to both receptors over the (R)-enantiomers. The relative potency of the enantiomers to the CB2 receptor is affected by structural features. The difference was more pronounced for compounds with an amine moiety (AB-FUBINACA and AB-CHMINACA) than those with an ester moiety (AMB-FUBINACA and 5F-MDMB-PINACA). An HPLC method was developed to determine the prevalence of (R)-enantiomers in seized samples. Lux® Amylose-1 [Amylose tris(3,5-dimethylphenylcarbamate)] has the greatest selectivity for the SCRAs with a terminal methyl ester moiety and a Lux® i-Cellulose-5 column for SCRAs with a terminal amide moiety. Optimized isocratic separation methods yielded enantiomer resolution values (Rs) ≥ 1.99. Achiral GC-MS analysis of seized herbal materials (n = 16), found 5F-MDMB-PINACA (<1.0-91.5 mg/g herbal material) and AMB-FUBINACA (15.5-58.5 mg/g herbal material), respectively. EMB-FUBINACA, AMB-CHMICA, 5F-ADB-PINACA isomer 2, and ADB-CHMINACA were also tentatively identified. Analysis using chiral chromatography coupled to photodiode array and quadrupole time of flight mass spectrometry (chiral HPLC-PDA-QToF-MS/MS) confirmed that the (S)-enantiomer predominated in all samples (93.6-99.3% (S)-enantiomer). Small but significant differences in synthesis precursor enantiopurity may provide significant differences between synthesis batches or suppliers and warrants further study. A method to compare potency between samples containing different SCRAs at varying concentrations was developed and applied in this small preliminary study. A 10-fold difference in the "intrinsic" potency of samples in the study was noted. With the known heterogeneity of SCRA infused materials, the approach provides a simplified method for assessing and communicating the risk of their use.

Synthetic Cannabinoid Hydroxypentyl Metabolites Retain Efficacy at Human Cannabinoid Receptors

Synthetic cannabinoids (SCs) are novel psychoactive substances that are easily acquired, widely abused as a substitute for cannabis, and associated with cardiotoxicity and seizures. Although the structural bases of these compounds are scaffolds with known affinity and efficacy at the human cannabinoid type-1 receptor (hCB1), upon ingestion or inhalation they can be metabolized to multiple chemical entities of unknown pharmacological activity. A large proportion of these metabolites are hydroxylated on the pentyl chain, a key substituent that determines receptor affinity and selectivity. Thus, the pharmacology of SC metabolites may be an important component in understanding the in vivo effects of SCs. We examined nine SCs (AB-PINACA, 5F-AB-PINACA, ADB/MDMB-PINACA, 5F-ADB, 5F-CUMYL-PINACA, AMB-PINACA, 5F-AMB, APINACA, and 5F-APINACA) and their hydroxypentyl (either 4-OH or 5-OH) metabolites in [3H]CP55,940 receptor binding and the [35S]GTPγS functional assay to determine the extent to which these metabolites retain activity at cannabinoid receptors. All of the SCs tested exhibited high affinity (<10 nM) and efficacy for hCB1 and hCB2 The majority of the hydroxypentyl metabolites retained full efficacy at hCB1 and hCB2, albeit with reduced affinity and potency, and exhibited greater binding selectivity for hCB2 These data suggest that phase I metabolites may be contributing to the in vivo pharmacology and toxicology of abused SCs. Considering this and previous reports demonstrating that metabolites retain efficacy at the hCB1 receptor, the full pharmacokinetic profiles of the parent compounds and their metabolites need to be considered in terms of the pharmacological effects and time course associated with these drugs.