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Objective: The cannabinoid cannabidiol has established antiseizure effects in drug-resistant epilepsies such as Dravet syndrome and Lennox-Gastaut syndrome. Amorfrutin 2, honokiol, and magnolol are structurally similar to cannabinoids (cannabis-like drugs) but derive from non-cannabis plants. We aimed to study the antiseizure potential of these compounds in various mouse seizure models. In addition, we aimed to characterize their molecular pharmacology at cannabinoid CB 1 and CB 2 receptors and at T-type calcium channels, which are known targets of the cannabinoids., Methods: Brain and plasma pharmacokinetic profiles were determined. Antiseizure activity was assessed against hyperthermia-induced seizures in a Scn1a +/- mouse model of Dravet syndrome. We then elaborated on the most promising compounds in the maximal electroshock (MES) test in mice and the Gabrb3 +/D120N mouse model of Lennox-Gastaut syndrome. Fluorescence-based assays were used to examine modulatory activity at cannabinoid CB 1 and CB 2 receptors and T-type calcium channel subtypes Ca V 3.1, Ca V 3.2, and Ca V 3.3 overexpressed in mammalian cells. Automated patch-clamp electrophysiology was then used to confirm inhibitory activity on Ca V 3.1, Ca V 3.2, and Ca V 3.3 channels., Results: Magnolol and honokiol had high brain-to-plasma ratios (3.55 and 7.56, respectively), unlike amorfrutin 2 (0.06). Amorfrutin 2 and magnolol but not honokiol significantly increased the body temperature threshold at which Scn1a +/- mice had a generalized tonic-clonic seizure. Both amorfrutin 2 and magnolol significantly decreased the proportion of mice exhibiting hindlimb extension in the MES test. Furthermore, magnolol reduced the number and duration of atypical absence seizures in Gabrb3 +/D120N mice. The three compounds inhibited all T-type calcium channel subtypes but were without specific activity at cannabinoid receptors., Significance: We show for the first time that amorfrutin 2 and magnolol display novel antiseizure activity in mouse drug-resistant epilepsy models. Our results justify future drug discovery campaigns around these structural scaffolds that aim to develop novel antiseizure drugs for intractable epilepsies., (© 2024 International League Against Epilepsy.)

Synthetic cannabinoid receptor agonists (SCRAs) are a growing class of new psychoactive substances (NPS) commonly derived from an N -alkylated indole, indazole, or 7-azaindole scaffold. Diversification of this core (at the 3-position) with amide-linked pendant amino acid groups and modular N -alkylation (of the indole/indazole/7-azaindole core) ensures that novel SCRAs continue to enter the illicit drug market rapidly. In response to the large number of SCRAs that have been detected, pharmacological evaluation of this NPS class has become increasingly common. Adamantane-derived SCRAs have consistently appeared throughout the market since 2011, and as such, a systematic set of these derivatives was synthesized and pharmacologically evaluated. Deuterated and fluorinated adamantane derivatives were prepared to evaluate typical hydrogen bioisosteres, as well as evaluation of the newly detected AFUBIATA.

ADB-HEXINACA has been recently reported as a synthetic cannabinoid receptor agonist (SCRA), one of the largest classes of new psychoactive substances (NPSs). This compound marks the entry of the n -hexyl tail group into the SCRA landscape, which has continued in the market with recent, newly detected SCRAs. As such, a proactive characterization campaign was undertaken, including the synthesis, characterization, and pharmacological evaluation of ADB-HEXINACA and a library of 41 closely related analogues. Two in vitro functional assays were employed to assess activity at CB 1 and CB 2 cannabinoid receptors, measuring G βγ -coupled agonism through a fluorescence-based membrane potential assay (MPA) and β-arrestin 2 (βarr2) recruitment via a live cell-based nanoluciferase complementation reporter assay. ADB-HEXINACA was a potent and efficacious CB 1 agonist (CB 1 MPA pEC 50 = 7.87 ± 0.12 M; E max = 124 ± 5%; βarr2 pEC 50 = 8.27 ± 0.14 M; E max = 793 ± 42.5), as were most compounds assessed. Isolation of the heterocyclic core and alkyl tails allowed for the comprehensive characterization of structure-activity relationships in this compound class, which were rationalized in silico via induced fit docking experiments. Overall, most compounds assessed are possibly emerging NPSs.

Synthetic cannabinoid receptor agonists (SCRAs) comprise the second largest class of new psychoactive substances (NPS), and typically α-amino acid moieties are incorporated as part of their design. Limited investigation has been performed into elucidating structure-activity relationships around commonly used α-amino acid-derived head groups, mainly with valine and tert -leucine-derived compounds previously described. As such, proactive synthesis, characterisation and pharmacological evaluation were performed to explore structure-activity relationships of 15 α-amino acid derivatives, with both the natural isomers and their enantiomers at CB 1 and CB 2 investigated using a fluorescence-based membrane potential assay. This library was based around the detected SCRAs MPP-5F-PICA, MMB-5F-PICA, and MDMB-5F-PICA, with the latter showing significant receptor activation at CB 1 (pEC 50 = 8.34 ± 0.05 M; E max = 108 ± 3%) and CB 2 (pEC 50 = 8.13 ± 0.07 M; E max = 99 ± 2%). Most valine and leucine derivatives were potent and efficacious SCRAs, while smaller derivatives generally showed reduced activity at CB 1 and CB 2 , and larger derivatives also showed reduced activity. SAR trends observed were rationalised via in silico induced fit docking. Overall, while natural enantiomers showed equipotent or greater activity than the unnatural isomers in most cases, this was not universal. As such, a number of these compounds should be monitored as emerging NPS, and various substituents described herein., Competing Interests: There are no financial or other relations that could lead to a conflict of interest., (This journal is © The Royal Society of Chemistry.)

The cannabinoid CB 1 receptor (CB 1 ) 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 Δ 9 -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 CB 1 , rather than biased agonism., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

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 CB 2 receptor (CB 2 ). Hence, the current study aimed to characterize the molecular pharmacology of a structurally diverse panel of SCRAs at CB 2 , 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 CB 2 -expressing HEK 293 cells: G protein activation (Gα i3 and Gα oB ), 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 CB 2 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 CB 2 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 CB 2 contributes to the toxicity of these compounds., (© 2023 The Authors. Pharmacology Research & Perspectives published by British Pharmacological Society and American Society for Pharmacology and Experimental Therapeutics and John Wiley & Sons Ltd.)

Background: T-type Ca 2+ channels (Ca v 3) represent emerging therapeutic targets for a range of neurological disorders, including epilepsy and pain. To aid the development and optimisation of new therapeutics, there is a need to identify novel chemical entities which act at these ion channels. A number of synthetic cannabinoid receptor agonists (SCRAs) have been found to exhibit activity at T-type channels, suggesting that cannabinoids may provide convenient chemical scaffolds on which to design novel Ca v 3 inhibitors. However, activity at cannabinoid type 1 (CB 1 ) receptors can be problematic because of central and peripheral toxicities associated with potent SCRAs. The putative SCRA MEPIRAPIM and its analogues were recently identified as Ca v 3 inhibitors with only minimal activity at CB 1 receptors, opening the possibility that this scaffold may be exploited to develop novel, selective Ca v 3 inhibitors. Here we present the pharmacological characterisation of SB2193 and SB2193F, two novel Ca v 3 inhibitors derived from MEPIRAPIM. Methods: The potency of SB2193 and SB2193F was evaluated in vitro using a fluorometric Ca 2+ flux assay and confirmed using whole-cell patch-clamp electrophysiology. In silico docking to the cryo-EM structure of Ca v 3.1 was also performed to elucidate structural insights into T-type channel inhibition. Next, in vivo pharmacokinetic parameters in mouse brain and plasma were determined using liquid chromatography-mass spectroscopy. Finally, anticonvulsant activity was assayed in established genetic and electrically-induced rodent seizure models. Results: Both MEPIRAPIM derivatives produced potent inhibition of Ca v 3 channels and were brain penetrant, with SB2193 exhibiting a brain/plasma ratio of 2.7. SB2193 was further examined in mouse seizure models where it acutely protected against 6 Hz-induced seizures. However, SB2193 did not reduce spontaneous seizures in the Scn1a +/- mouse model of Dravet syndrome, nor absence seizures in the Genetic Absence Epilepsy Rat from Strasbourg (GAERS). Surprisingly, SB2193 appeared to increase the incidence and duration of spike-and-wave discharges in GAERS animals over a 4 h recording period. Conclusion: These results show that MEPIRAPIM analogues provide novel chemical scaffolds to advance Ca v 3 inhibitors against certain seizure types., Competing Interests: JA, RL, and IM have served as expert witnesses in various medicolegal cases involving cannabis and cannabinoids. JA, LA, and IM. hold patents on cannabinoid therapies (PCT/AU2018/05089 and PCT/AU2019/050554). JA has received consulting fees from Creo Inc. and Medicinal Cannabis Industry Australia (MCIA). RL acts as a consultant to Shackleford Pharma Inc. IM acts as a consultant to Kinoxis Therapeutics and has received honoraria from Janssen. He has also received consulting fees from MCIA. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Harman, Udoh, McElroy, Anderson, Kevin, Banister, Ametovski, Markham, Bladen, Doohan, Greba, Laprairie, Snutch, McGregor, Howland and Arnold.)

A purified preparation of cannabidiol (CBD), a cannabis constituent, has been approved for the treatment of intractable childhood epilepsies such as Dravet syndrome. Extensive pharmacological characterization of CBD shows activity at numerous molecular targets but its anticonvulsant mechanism(s) of action is yet to be delineated. Many suggest that the anticonvulsant action of CBD is the result of G protein-coupled receptor 55 (GPR55) inhibition. Here we assessed whether Gpr55 contributes to the strain-dependent seizure phenotypes of the Scn1a+/- mouse model of Dravet syndrome. The Scn1a+/- mice on a 129S6/SvEvTac (129) genetic background have no overt phenotype, while those on a [129 x C57BL/6J] F1 background exhibit a severe phenotype that includes hyperthermia-induced seizures, spontaneous seizures and reduced survival. We observed greater Gpr55 transcript expression in the cortex and hippocampus of mice on the seizure-susceptible F1 background compared to those on the seizure-resistant 129 genetic background, suggesting that Gpr55 might be a genetic modifier of Scn1a+/- mice. We examined the effect of heterozygous genetic deletion of Gpr55 and pharmacological inhibition of GPR55 on the seizure phenotypes of F1.Scn1a+/- mice. Heterozygous Gpr55 deletion and inhibition of GPR55 with CID2921524 did not affect the temperature threshold of a thermally-induced seizure in F1.Scn1a+/- mice. Neither was there an effect of heterozygous Gpr55 deletion observed on spontaneous seizure frequency or survival of F1.Scn1a+/- mice. Our results suggest that GPR55 antagonism may not be a suitable anticonvulsant target for Dravet syndrome drug development programs, although future research is needed to provide more definitive conclusions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. We confirm that this does not alter our adherence to all PLOS ONE policies on sharing data and materials., (Copyright: © 2023 Anderson et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Over 200 synthetic cannabinoid receptor agonists (SCRAs) have been identified as new psychoactive substances. Effective monitoring and characterization of SCRAs are hindered by the rapid pace of structural evolution. Ahead of possible appearance on the illicit drug market, new SCRAs were synthesized to complete a systematic library of cumyl-indole- ( e.g. , CUMYL-CPrMICA, CUMYL-CPMICA) and cumyl-indazole-carboxamides ( e.g. , CUMYL-CPrMINACA, CUMYL-CPMINACA), encompassing butyl, pentyl, cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl, and cyclohexylmethyl tails. Comprehensive pharmacological characterization was performed with three assay formats, monitoring the recruitment of either wild-type or C-terminally truncated (βarr2d366) β-arrestin2 to the activated cannabinoid 1 receptor (CB 1 ) or monitoring G βγ -mediated membrane hyperpolarization. Altered compound characterization was observed when comparing derived potency (EC 50 ) and efficacy ( E max ) values from both assays monitoring the same or a different signaling event, whereas ranges and ranking orders were similar. Structure-activity relationships (SAR) were assessed in threefold, resulting in the identification of the pendant tail as a critical pharmacophore, with the optimal chain length for CB 1 activation approximating an n- pentyl ( e.g. , cyclopentylmethyl or cyclohexylmethyl tail). The activity of the SCRAs encompassing cyclic tails decreased with decreasing number of carbons forming the cyclic moiety, with CUMYL-CPrMICA showing the least CB 1 activity in all assay formats. The SARs were rationalized via molecular docking, demonstrating the importance of the optimal steric contribution of the hydrophobic tail. While SAR conclusions remained largely unchanged, the differential compound characterization by both similar and different assay designs emphasizes the importance of detailing specific assay characteristics to allow adequate interpretation of potencies and efficacies.

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 (CB 1 ) was investigated to determine the activity of the metabolite., Methods: The effect of CES1 and CES2 inhibitors, and delta-9-tetrahydrocannabinol (Δ 9 -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 CB 1 ., 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 Δ 9 -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 CB 1 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., (© 2022. The Author(s).)

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 Δ 9 -tetrahydrocannabinol (Δ 9 -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 H 1 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 Δ 9 -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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Kevin, Cairns, Boyd, Arnold, Bowen, McGregor and Banister.)

Synthetic cannabinoid receptor agonists (SCRAs) continue to make up a significant portion new psychoactive substances (NPS) detected and seized worldwide. Due to their often potent activation of central cannabinoid receptors in vivo , use of SCRAs can result in severe intoxication, in addition to other adverse health effects. Recent detections of AB-4CN-BUTICA, MMB-4CN-BUTINACA, MDMB-4F-BUTICA and MDMB-4F-BUTINACA mark a continuation in the appearance of SCRAs bearing novel tail substituents. The proactive characterization campaign described here has facilitated the detection of several new SCRAs in toxicological case work. Here we detail the synthesis, characterization, and pharmacological evaluation of recently detected SCRAs, as well as a systematic library of 32 compounds bearing head, tail, and core group combinations likely to appear in future. In vitro radioligand binding assays revealed most compounds showed moderate to high affinity at both CB 1 (p K i = < 5 to 8.89 ± 0.09 M) and CB 2 (p K i = 5.49 ± 0.03 to 9.92 ± 0.09 M) receptors. In vitro functional evaluation using a fluorescence-based membrane potential assay showed that most compounds were sub-micromolar to sub-nanomolar agonists at CB 1 (pEC 50 = < 5 to 9.48 ± 0.14 M) and CB 2 (pEC 50 = 5.92 ± 0.16 to 8.64 ± 0.15 M) receptors. An in silico receptor-ligand docking approach was utilized to rationalize binding trends for CB 2 with respect to the tail substituent, and indicated that rigidity in this region (i.e., 4-cyanobutyl) was detrimental to affinity., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Sparkes, Boyd, Chen, Markham, Luo, Foyzun, Zaman, Fletcher, Ellison, McGregor, Santiago, Lai, Gerona, Connor, Hibbs, Cairns, Glass, Ametovski and Banister.)

Background: Purified cannabidiol (CBD), a non-psychoactive phytocannabinoid, has gained regulatory approval to treat intractable childhood epilepsies. Despite this, artisanal and commercial CBD-dominant hemp-based products continue to be used by epilepsy patients. Notably, the CBD doses used in these latter products are much lower than that found to be effective in reducing seizures in clinical trials with purified CBD. This might be because these CBD-dominant hemp products contain other bioactive compounds, including phytocannabinoids and terpenes, which may exert unique effects on epilepsy-relevant drug targets. Voltage-gated sodium (Na V ) channels are vital for initiation of neuronal action potential propagation and genetic mutations in these channels result in epilepsy phenotypes. Recent studies suggest that Na V channels are inhibited by purified CBD. However, the effect of cannabis-based products on the function of Na V channels is unknown., Methods: Using automated-planar patch-clamp technology, we profile a hemp-derived nutraceutical product (NP) against human Na V 1.1-Na V 1.8 expressed in mammalian cells to examine effects on the biophysical properties of channel conductance, steady-state fast inactivation and recovery from fast inactivation., Results: NP modifies peak current amplitude of the Na V 1.1-Na V 1.7 subtypes and has variable effects on the biophysical properties for all channel subtypes tested. NP potently inhibits Na V channels revealing half-maximal inhibitory concentration (IC 50 ) values of between 1.6 and 4.2 μg NP/mL. Purified CBD inhibits Na V 1.1, Na V 1.2, Na V 1.6 and Na V 1.7 to reveal IC 50 values in the micromolar range. The CBD content of the product equates to IC 50 values (93-245 nM), which are at least an order of magnitude lower than purified CBD. Unlike NP, hemp seed oil vehicle alone did not inhibit Na V channels, suggesting that the inhibitory effects of NP are independent of hemp seed oil., Conclusions: This CBD-dominant NP potently inhibits Na V channels. Future study of the individual elements of NP, including phytocannabinoids and terpenes, may reveal a potent individual component or that its components interact to modulate Na V channels., (© 2022. The Author(s).)

Cannabichromene (CBC) and cannabichromenic acid (CBCA) are cannabis constituents currently under evaluation for their therapeutic potential, but their pharmacological properties have not been thoroughly investigated. The most studied ATP-binding cassette (ABC) transporters, ABC subfamily G member 2 (ABCG2) and ABC subfamily B member 1 (ABCB1) limit absorption of substrate drugs in the gut and brain. Moreover, inhibitors of these proteins can lead to clinically significant drug-drug interactions (DDIs). The current study sought to examine whether CBC and CBCA affect ABCB1 and ABCG2 to advance their basic pharmacological characterisation. The plant cannabinoids CBC and CBCA were screened in vitro in a bidirectional transport assay to determine whether they were substrates and/or inhibitors of ABCB1 and ABCG2. Transwell assays with polarized epithelial Madin-Darby Canine Kidney II (MDCK) cells expressing ABCB1 or ABCG2 were used. Samples were measured using liquid chromatography tandem mass spectrometry (LC-MS/MS). CBCA was found to be an ABCB1 substrate, but not an ABCG2 substrate. CBC was not a substrate of either transporter. Neither CBCA nor CBC inhibited ABCB1 transport of prazosin or ABCG2 transport of digoxin. In silico molecular docking suggested CBCA binds ABCB1 in the access tunnel and the central binding pocket. CBC, an agent with anticonvulsant, anti-inflammatory and anti-depressant properties, is not a substrate or inhibitor of ABCB1 or ABCG2, which is favourable to its therapeutic development. CBCA is an ABCB1 substrate in vitro which might contribute to its poor absorption. These findings provide important basic pharmacological data to assist the therapeutic development of these cannabis constituents., (Copyright © 2022. Published by Elsevier B.V.)

Synthetic cannabinoid receptor agonists (SCRAs) are a large and growing class of new psychoactive substances (NPSs). Two recently identified compounds, MEPIRAPIM and 5F-BEPIRAPIM (NNL-2), have not been confirmed as agonists of either cannabinoid receptor subtype but share structural similarities with both SCRAs and a class of T-type calcium channel (Ca V 3) inhibitors under development as new treatments for epilepsy and pain. In this study, MEPIRAPIM and 5F-BEPIRAPIM and 10 systematic analogues were synthesized, analytically characterized, and pharmacologically evaluated using in vitro cannabinoid receptor and Ca V 3 assays. Several compounds showed micromolar affinities for CB 1 and/or CB 2 , with several functioning as low potency agonists of CB 1 and CB 2 in a membrane potential assay. 5F-BEPIRAPIM and four other derivatives were identified as potential Ca V 3 inhibitors through a functional calcium flux assay (>70% inhibition), which was further confirmed using whole-cell patch-clamp electrophysiology. Additionally, MEPIRAPIM and 5F-BEPIRAPIM were evaluated in vivo using a cannabimimetic mouse model. Despite detections of MEPIRAPIM and 5F-BEPIRAPIM in the NPS market, only the highest MEPIRAPIM dose (30 mg/kg) elicited a mild hypothermic response in mice, with no hypothermia observed for 5F-BEPIRAPIM, suggesting minimal central CB 1 receptor activity.

Synthetic cannabinoid receptor agonists (SCRAs) are a diverse class of new psychoactive substances (NPS). They commonly comprise N -alkylated indole, indazole, or 7-azaindole scaffolds with amide-linked pendant amino acid groups. To explore the contribution of the amino acid side chain to the cannabinoid pharmacology of SCRA NPS, a systematic library of side chain-modified SCRAs was prepared based on the recent detections of amino acid derivatives 17 (5F-AB-PINACA), 18 (5F-ADB-PINACA), 15 (PX-1), 19 (PX-2), and 20 (NNL-1). In vitro binding affinities and functional activities at cannabinoid type 1 and 2 receptors (CB 1 and CB 2 , respectively) were determined for all the library members using radioligand competition experiments and a fluorescence-based membrane potential assay. Binding affinities and functional activities varied widely across compounds ( K i = 0.32 to >10 000 nM, EC 50 = 0.24-1259 nM), with several clear structure-activity relationships (SARs) emerging. Affinity and potency at CB 1 changed as a function of the heterocyclic core (indazole > indole > 7-azaindole) and the pendant amino acid side chain ( tert -butyl > iso -propyl > iso -butyl > benzyl > ethyl > methyl > hydrogen). Ensemble docking at CB 1 revealed a clear steric basis for observed SAR trends. Interestingly, although 15 (PX-1) and 19 (PX-2) have been detected in recreational drug markets, they failed to induce centrally CB 1 -mediated effects (e.g., hypothermia) in mice using radiobiotelemetry. Together, these data provide insights regarding structural contributions to the cannabimimetic profiles of 17 (5F-AB-PINACA), 18 (5F-ADB-PINACA), 15 (PX-1), 19 (PX-2), 20 (NNL-1), and other SCRA NPS.

Objective: Cannabigerolic acid (CBGA), a precursor cannabinoid in Cannabis sativa, has recently been found to have anticonvulsant properties in the Scn1a +/- mouse model of Dravet syndrome. Poor brain penetration and chemical instability of CBGA limits its potential as an anticonvulsant therapy. Here, we examined whether CBGA methyl ester, a more stable analogue of CBGA, might have superior pharmacokinetic and anticonvulsant properties. In addition, we examined whether olivetolic acid, the biosynthetic precursor to CBGA with a truncated (des-geranyl) form, might possess minimum structural requirements for anticonvulsant activity. We also examined whether olivetolic acid and CBGA methyl ester retain activity at the epilepsy-relevant drug targets of CBGA: G-protein-coupled receptor 55 (GPR55) and T-type calcium channels., Methods: The brain and plasma pharmacokinetic profiles of CBGA methyl ester and olivetolic acid were examined following 10 mg/kg intraperitoneal (i.p.) administration in mice (n = 4). The anticonvulsant potential of each was examined in male and female Scn1a +/- mice (n = 17-19) against hyperthermia-induced seizures (10-100 mg/kg, i.p.). CBGA methyl ester and olivetolic acid were also screened in vitro against T-type calcium channels and GPR55 using intracellular calcium and ERK phosphorylation assays, respectively., Results: CBGA methyl ester exhibited relatively limited brain penetration (13%), although somewhat superior to that of 2% for CBGA. No anticonvulsant effects were observed against thermally induced seizures in Scn1a +/- mice. Olivetolic acid also showed poor brain penetration (1%) but had a modest anticonvulsant effect in Scn1a +/- mice increasing the thermally induced seizure temperature threshold by approximately 0.4°C at a dose of 100 mg/kg. Neither CBGA methyl ester nor olivetolic acid displayed pharmacological activity at GPR55 or T-type calcium channels., Conclusions: Olivetolic acid displayed modest anticonvulsant activity against hyperthermia-induced seizures in the Scn1a +/- mouse model of Dravet syndrome despite poor brain penetration. The effect was, however, comparable to the known anticonvulsant cannabinoid cannabidiol in this model. Future studies could explore the anticonvulsant mechanism(s) of action of olivetolic acid and examine whether its anticonvulsant effect extends to other seizure types., (© 2021. The Author(s).)

Synthetic cannabinoid receptor agonists (SCRAs) remain a prolific class of new psychoactive substances (NPS) and continue to expand rapidly. Despite the recent identification of hydroxybenzotriazole (HOBt) containing SCRAs in synthetic cannabis samples, there is currently no information regarding the pharmacological profile of these NPS with respect to human CB 1 and CB 2 receptors. In the current study, a series consisting of seven HOBt indole-, indazole-, and 7-azaindole-carboxylates bearing a range of N -alkyl substituents were synthesized and pharmacologically evaluated. Competitive binding assays at CB 1 and CB 2 demonstrated that all analogues except a 2-methyl-substituted derivative had low affinity for CB 1 ( K i = 3.80-43.7 μM) and CB 2 ( K i = 2.75-18.2 μM). A fluorometric functional assay revealed that 2-methylindole- and indole-derived HOBt carboxylates were potent and efficacious agonists of CB 1 (EC 50 = 12.0 and 63.7 nM; E max = 118 and 120%) and CB 2 (EC 50 = 10.9 and 321 nM; E max = 91 and 126%). All other analogues incorporating indazole and 7-azaindole cores and bearing a range of N1-substituents showed relatively low potency for CB 1 and CB 2 . Additionally, a reporter assay monitoring β-arrestin 2 (βarr2) recruitment to the receptor revealed that the 2-methylindole example was the most potent and efficacious at CB 1 (EC 50 = 131 nM; E max = 724%) and the most potent at CB 2 (EC 50 = 38.2 nM; E max = 51%). As with the membrane potential assay, the indazole and other indole HOBt carboxylates were considerably less potent at both receptors, and analogues comprising a 7-azaindole core showed little activity. Taken together, these data suggest that NNL-3 demonstrates little CB1 receptor activity and is unlikely to be psychoactive in humans. NNL-3 is likely an unintended SCRA manufacturing byproduct. However, the synthesis of NNL-3 analogues proved simple and general, and some of these showed potent cannabimetic profiles in vitro , indicating that HOBt esters of this type may represent an emerging class of SCRA NPS.

Synthetic cannabinoid receptor agonists (SCRAs) remain one the most prevalent classes of new psychoactive substances (NPS) worldwide, and examples are generally poorly characterised at the time of first detection. We have synthesised a systematic library of amino acid-derived indole-, indazole-, and 7-azaindole-3-carboxamides related to recently detected drugs ADB-BUTINACA, APP-BUTINACA and ADB-P7AICA, and characterised these ligands for in vitro binding and agonist activity at cannabinoid receptor subtypes 1 and 2 (CB 1 and CB 2 ), and in vivo cannabimimetic activity. All compounds showed high affinity for CB 1 ( K i 0.299-538 nM) and most at CB 2 ( K i = 0.912-2190 nM), and most functioned as high efficacy agonists of CB 1 and CB 2 in a fluorescence-based membrane potential assay and a βarr2 recruitment assay (NanoBiT®), with some compounds being partial agonists in the NanoBiT® assay. Key structure-activity relationships (SARs) were identified for CB 1 /CB 2 binding and CB 1 /CB 2 functional activities; (1) for a given core, affinities and potencies for tert -leucinamides (ADB-) > valinamides (AB-) ≫ phenylalaninamides (APP-); (2) for a given amino acid side-chain, affinities and potencies for indazoles > indoles ≫ 7-azaindoles. Radiobiotelemetric evaluation of ADB-BUTINACA, APP-BUTINACA and ADB-P7AICA in mice demonstrated that ADB-BUTINACA and ADB-P7AICA were cannabimimetic at 0.1 mg kg -1 and 10 mg kg -1 doses, respectively, as measured by pronounced decreases in core body temperature. APP-BUTINACA failed to elicit any hypothermic response up to the maximally tested 10 mg kg -1 dose, yielding an in vivo potency ranking of ADB-BUTINACA > ADB-P7AICA > APP-BUTINACA., Competing Interests: None., (This journal is © The Royal Society of Chemistry.)

Synthetic cannabinoid receptor agonists (SCRAs) are the second largest class of new psychoactive substances (NPS) and are associated with serious adverse effects and even death. Despite this, little pharmacological data are available for many of the most recent SCRAs. This study consists of three different parts, aiming to systematically evaluate a panel of 30 SCRAs using binding and different in vitro human cannabinoid 1 receptor (CB 1 ) activation assays. The present Part II investigated the SCRA analogs for their CB 1 activation via a β-arrestin recruitment assay. The panel was systematically designed to include key structural sub-features of recent SCRAs. Thus, the 4-pentenyl tail of MMB-4en-PICA and MDMB-4en-PINACA was retained while incorporating varying head groups from other prevalent SCRAs, including amides and esters of L-valine, L-tert-leucine, and L-phenylalanine, and adamantyl and cumyl moieties. All 30 SCRAs activated CB 1 , with indazoles generally showing the greatest potency (EC 50  = 1.88-281 nM), followed by indoles (EC 50  = 11.5-2293 nM), and the corresponding 7-azaindoles (EC 50  = 62.4-9251 nM). Several subunit-linked structure-activity relationships were identified: (i) tert-leucine-functionalized SCRAs were more potent than the corresponding valine derivatives; (ii) no major difference in potency or efficacy was observed between tert-leucine/valine-derived amides and the corresponding methyl esters; however, phenylalanine analogs were affected by this change; and (iii) minor structural changes to the 4-pentenyl substituent had little influence on activity. These findings elucidate structural features that modulate the CB 1 activation potential of currently prevalent SCRAs and a systematic panel of analogs, some of which may appear in NPS markets in future., (© 2021 John Wiley & Sons, Ltd.)

The present work is the last of a three-part study investigating a panel of 30 systematically designed synthetic cannabinoid receptor agonists (SCRAs) including features such as the 4-pentenyl tail and varying head groups including amides and esters of l-valine (MMB, AB), l-tert-leucine (ADB), and l-phenylalanine (APP), as well as adamantyl (A) and cumyl moieties (CUMYL). Here, we evaluated these SCRAs for their capacity to activate the human cannabinoid receptor 1 (CB 1 ) via indirect measurement of G protein recruitment. Furthermore, we comparatively evaluated the results obtained from three in vitro assays, based on the recruitment of β-arrestin 2 (βarr2 assay) or Gα i protein (mini-Gα i assay), or binding of [ 35 S]-GTPγS. The observed efficacies (E max ) varied depending on the conducted assay. Statistical analysis suggests that the population means of the relative intrinsic activity (RA i ) significantly differ for the [ 35 S]-GTPγS assay and the other two assays, but the population means of the βarr2 and mini-Gα i assays were not statistically different. Our data suggest that differences observed between the βarr2 and mini-Gα i assays are the best predictor for 'biased agonism' towards βarr or G protein recruitment in our study. SCRAs carrying an ADB or MPP moiety as a head group tended to produce elevated E max values in the βarr2 assay, which might result in a tendency of these compounds to cause pronounced tolerance in users-a hypothesis that should be evaluated further by future studies. In general, a comparison of efficacies derived from different assays is difficult and should only be conducted very cautiously., (© 2021 The Authors. Drug Testing and Analysis published by John Wiley & Sons Ltd.)

Synthetic cannabinoid receptor agonists (SCRAs) are one of the largest and most structurally diverse classes of new psychoactive substances (NPS). Despite this, pharmacological data are often lacking following the identification of a new SCRA in drug markets. In this first of a three-part series, we describe the synthesis, analytical characterization, and binding affinity of a proactively generated, systematic library of 30 indole, indazole, and 7-azaindole SCRAs related to MMB-4en-PICA, MDMB-4en-PINACA, ADB-4en-PINACA, and MMB-4CN-BUTINACA featuring a 4-pentenyl (4en-P), butyl (B/BUT), or 4-cyanobutyl (4CN-B/BUT) tail and a methyl l-valinate (MMB), methyl l-tert-leucinate (MDMB), methyl l-phenylalaninate (MPP), l-valinamide (AB), l-tert-leucinamide (ADB), l-phenylalaninamide (APP), adamantyl (A), or cumyl head group. Competitive radioligand binding assays demonstrated that the indazole core conferred the highest CB 1 binding affinity (K i  = 0.17-39 nM), followed by indole- (K i  = 0.95-160 nM) and then 7-azaindole-derived SCRAs (K i  = 5.4-271 nM). Variation of the head group had the greatest effect on binding, with tert-leucine amides and methyl esters (K i  = 0.17-14 nM) generally showing the greatest affinities, followed by valine derivatives (K i  = 0.72-180 nM), and then phenylalanine derivatives (K i  = 2.5-271 nM). Adamantyl head groups (K i  = 8.8-59 nM) were suboptimal for binding, whereas the cumyl analogues consistently conferred high affinity (K i  = 0.62-36 nM). Finally, both butyl (K i  = 3.1-163 nM) and 4-cyanobutyl (K i  = 5.5-44 nM) tail groups were less favorable for CB 1 binding than their corresponding 4-pentenyl counterparts (K i  = 0.72-25 nM)., (© 2021 John Wiley & Sons, Ltd.)

Cannabidiol is claimed to bind to a large number of protein targets based on in vitro assays. This suggests opportunities for a wide range of therapeutic applications. On the other hand, the existence of phytochemical 'nuisance compounds' suggests some measure of caution - these compounds are capable of altering membrane biophysical properties and changing protein function without directly contacting a binding site. Like cannabidiol, cholesterol alters membrane properties, but it also binds directly to membrane proteins through abundant cholesterol recognition sites. We present the evidence that cannabidiol and cholesterol may bind to the same site on some proteins. As a starting point for further research, we also used blind docking to show that cannabidiol binds to a cholesterol binding site on the CB1 receptor. Elucidation of the mechanism(s) of action of cannabidiol will assist the prioritisation of in vitro hits across targets, improve the success rate of medicinal chemistry campaigns, and ultimately benefit patient populations by focusing resources on programs with the most translational potential., (Copyright © 2021. Published by Elsevier Ltd.)

Cannabis-based products are increasingly being used to treat refractory childhood epilepsies such as Dravet syndrome. Cannabis contains at least 140 terpenophenolic compounds known as phytocannabinoids. These include the known anticonvulsant compound cannabidiol (CBD) and several molecules showing emergent anticonvulsant properties in animal models. Cannabichromene (CBC) is a phytocannabinoid frequently detected in artisanal cannabis oils used in the community by childhood epilepsy patients. Here we examined the brain and plasma pharmacokinetic profiles of CBC, cannabichromenic acid (CBCA), cannabichromevarin (CBCV), and cannabichromevarinic acid (CBCVA) following intraperitoneal administration in mice. The anticonvulsant potential of each was then tested against hyperthermia-induced seizures in the Scn1a +/- mouse model of Dravet syndrome. All phytocannabinoids within the CBC series were readily absorbed and showed substantial brain penetration (brain-plasma ratios ranging from 0.2 to 5.8). Anticonvulsant efficacy was evident with CBC, CBCA, and CBCVA, each significantly increasing the temperature threshold at which Scn1a +/- mice had a generalized tonic-clonic seizure. We synthesized a fluorinated derivative of CBC (5-fluoro-CBC), which showed improved brain penetration relative to the parent CBC molecule but not any greater anticonvulsant effect. Since CBC and derivatives are anticonvulsant in a model of intractable pediatric epilepsy, they may constitute part of the mechanism through which artisanal cannabis oils are anticonvulsant in patients.

Synthetic cannabinoid receptor agonists (SCRAs) are an evolving class of new psychoactive substances (NPS) with structurally diverse compounds emerging each year. Due to the rapid pace at which these drugs enter the market, there is often little or nil information regarding the pharmacology of these substances despite widespread human use. In this study, 12 recently emerged SCRAs (reported between 2018 and 2020) were synthesized, analytically characterized, and pharmacologically evaluated using a live cell-based nanoluciferase complementation reporter assay that monitors in vitro cannabinoid receptor type 1 (CB1) activation via its interaction with β-arrestin 2 (βarr2). All synthesized SCRAs acted as agonists of CB1, although differences in potency (EC 50 = 2.33-5475 nM) and efficacy ( E max = 37-378%) were noted, and several structure-activity relationships were identified. SCRAs featuring indazole cores (EC 50 = 2.33-159 nM) were generally of equal or greater potency than indole analogues (EC 50 = 32.9-330 nM) or 7-azaindole derivatives (EC 50 = 64.0-5475 nM). Interestingly, with the exception of APP-BINACA ( E max = 75.7%) and 5F-A-P7AICA ( E max = 37.4%), all SCRAs showed greater efficacy than the historical SCRA JWH-018 to which responses were normalized ( E max = 142-378%). The most potent CB1 agonists in the study were ADB-BINACA (EC 50 = 6.36 nM), 4F-MDMB-BINACA (EC 50 = 7.39 nM), and MDMB-4en-PINACA (EC 50 = 2.33 nM). Notably, all of these SCRAs featured an indazole core as well as a "bulky" tert -butyl moiety in the pendant amino acid side chain. This study confirms that recently detected SCRAs 4F-MDMB-BICA, 5F-MPP-PICA, MMB-4en-PICA, CUMYL-CBMICA, ADB-BINACA, APP-BINACA, 4F-MDMB-BINACA, MDMB-4en-PINACA, A-CHMINACA, 5F-AB-P7AICA, 5F-MDMB-P7AICA, and 5F-AP7AICA were all able to activate the CB1 receptor in vitro, albeit to different extents, and are potentially psychoactive in vivo. These results indicate that further evaluation of these widely used NPS is warranted to better understand the risks associated with human consumption of these drugs.

Synthetic cannabinoid receptor agonists (SCRAs) represent the most rapidly expanding class of new psychoactive substances (NPSs). Despite the prevalence and potency of recent chiral indole-3-carboxamide SCRAs, few pharmacological data are available regarding the enantiomeric bias of these NPSs toward human CB1 and CB2 receptors. A series of homochiral indole-3-carboxamides derived from ( S )- and ( R )- α- methylbenzylamine and featuring variation of the 1-alkyl substituent were prepared, pharmacologically evaluated, and compared to related achiral congeners derived from cumyl- and benzylamine. Competitive binding assays demonstrated that all analogues derived from either enantiomer of α- methylbenzylamine ( 14 - 17 ) showed affinities for CB1 ( K i = 47.9-813 nM) and CB2 ( K i = 47.9-347 nM) that were intermediate to that of the corresponding benzylic ( 10 - 13 , CB1 K i = 550 nM to >10 μM; CB2 K i = 61.7 nM to >10 μM) and cumyl derivatives ( 6 - 9 , CB1 K i = 12.6-21.4 nM; CB2 K i = 2.95-24.5 nM). In a fluorometric membrane potential assay, all α- methylbenzyl analogues (excluding 17 ) were potent, efficacious agonists of CB1 (EC 50 = 32-464 nM; E max = 89-104%) and low efficacy agonists of CB2 (EC 50 = 54-500 nM; E max = 52-77%), with comparable or greater potency than the benzyl analogues and much lower potency than the cumyl derivatives, consistent with binding trends. The relatively greater affinity and potency of ( S )- 14 - 17 compared to ( R )- 14 - 17 analogues at CB1 highlighted an enantiomeric bias for this series of SCRAs. Molecular dynamics simulations provided a conformational basis for the observed differences in agonist potency at CB1 pending benzylic substitution.

The sigma 1 receptor (S1R) is widely expressed in the CNS and is mainly located on the endoplasmic reticulum. The S1R is involved in the regulation of many neurotransmission systems and, indirectly, in neurodegenerative diseases. The S1R may therefore represent an interesting neuronal biomarker in neurodegenerative diseases such as Parkinson's (PD) or Alzheimer's diseases (AD). Here we present the characterisation of the S1R-specific 18 F-labelled tracer 18 F-IAM6067 in two animal models and in human brain tissue. Methods: Wistar rats were used for PET-CT imaging (60 min dynamic acquisition) and metabolite analysis (1, 2, 5, 10, 20, 60 min post-injection). To verify in vivo selectivity, haloperidol, BD1047 (S1R ligand), CM398 (S2R ligand) and SB206553 (5HT 2B/C antagonist) were administrated for pre-saturation studies. Excitotoxic lesions induced by intra-striatal injection of AMPA were also imaged by 18 F-IAM6067 PET-CT to test the sensitivity of the methods in a well-established model of neuronal loss. Tracer brain uptake was also verified by autoradiography in rats and in a mouse model of PD (intrastriatal 6-hydroxydopamine (6-OHDA) unilateral lesion). Finally, human cortical binding was investigated by autoradiography in three groups of subjects (control subjects with Braak ≤2, and AD patients, Braak >2 & ≤4 and Braak >4 stages). Results: We demonstrate that despite rapid peripheral metabolism of 18 F-IAM6067, radiolabelled metabolites were hardly detected in brain samples. Brain uptake of 18 F-IAM6067 showed differences in S1R anatomical distribution, namely from high to low uptake: pons-raphe, thalamus medio-dorsal, substantia nigra , hypothalamus, cerebellum, cortical areas and striatum. Pre-saturation studies showed 79-90% blockade of the binding in all areas of the brain indicated above except with the 5HT 2B/C antagonist SB206553 and S2R ligand CM398 which induced no significant blockade, indicating good specificity of 18 F-IAM6067 for S1Rs. No difference between ipsi- and contralateral sides of the brain in the mouse model of PD was detected. AMPA lesion induced a significant 69% decrease in 18 F-IAM6067 uptake in the globus pallidus matching the neuronal loss as measured by NeuN, but only a trend to decrease (-16%) in the caudate putamen despite a significant 91% decrease in neuronal count. Moreover, no difference in the human cortical binding was shown between AD groups and controls. Conclusion: This work shows that 18 F-IAM6067 is a specific and selective S1R radiotracer. The absence or small changes in S1R detected here in animal models and human tissue warrants further investigations and suggests that S1R might not be the anticipated ideal biomarker for neuronal loss in neurodegenerative diseases such as AD and PD., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Synthetic cannabinoid receptor agonists (SCRAs) represent the most rapidly proliferating class of "designer drugs" or "new psychoactive substances". SCRAs offer unregulated alternatives to cannabis that evade routine drug tests, but their use is increasingly associated with severe toxicity and death worldwide. Little is currently known about SCRA molecular pharmacology, or the mechanisms underpinning their toxicity, although the effects are believed to be primarily mediated by the type 1 cannabinoid receptor (CB 1 ). In this study, we aimed to characterise the signalling profiles of a structurally diverse panel of novel SCRAs at CB 1 . We compare SCRAs to traditional reference cannabinoids CP55,940, WIN55,212-2, and THC. The activity of the SCRAs was assessed in key receptor signalling and regulatory pathways, including cAMP production, translocation of β-arrestin 1 and 2, and receptor internalisation. The activity profiles of the ligands were also evaluated using operational analysis to identify ligand bias. Results revealed that SCRAs activities were relatively balanced in the pathways evaluated (compared to WIN55,212-2), although 5F-CUMYL-P7AICA and XLR-11 possessed partial efficacy in cAMP stimulation and β-arrestin translocation. Notably, the SCRAs showed distinct potency and efficacy profiles compared to THC. In particular, while the majority of SCRAs demonstrated robust β-arrestin translocation, cAMP stimulation, and internalisation, THC failed to elicit high efficacy responses in any of these assays. Further study is required to delineate if these pathways could contribute to SCRA toxicity in humans., (Crown Copyright © 2020. Published by Elsevier Inc. All rights reserved.)

Synthetic cannabinoid receptor agonists (SCRAs) are new psychoactive substances associated with acute intoxication and even death. However, the molecular mechanisms through which SCRAs may exert their toxic effects remain unclear-including the potential differential activation of G protein subtypes by cannabinoid receptor type 1 (CB1), a major target of SCRA. We measured CB1-mediated activation of Gα s and Gα i/o proteins by SCRAs by examining stimulation (pertussis toxin, PTX treated) as well as inhibition (non-PTX treated) of forskolin (FSK)-induced cyclic adenosine monophosphate (cAMP) accumulation in human embryonic kidney (HEK) cells stably expressing CB1. Real-time measurements of stimulation and inhibition of cAMP levels were made using a BRET biosensor. We found that the maximum concentration of SCRAs tested (10 µmol L -1 ), increased cAMP levels 12%-45% above that produced by FSK alone, while the phytocannabinoid THC did not significantly alter cAMP levels in PTX-treated HEK-CB1 cells. All SCRAs had greater potency to inhibit FSK-induced cAMP levels than to stimulate cAMP levels. The rank order of potencies for SCRA stimulation of cAMP (Gα s ) was PB-22 > 5F-MDMB-PICA > JWH-018 ≈ AB-FUBINACA > XLR-11. By contrast, the potency of SCRAs for inhibition of cAMP (Gα i/o ) was 5F-MDMB-PICA > AB-FUBINACA > PB-22 > JWH-018 > XLR-11. The different rank order of potency and E Max  of the SCRAs to stimulate Gα s -like signaling compared to Gα i/o signaling suggests differences in G protein preference between SCRAs. Understanding the apparent differences among these drugs may contribute to unravelling their complex effects in humans., (© 2020 The Authors. Pharmacology Research & Perspectives published by John Wiley & Sons Ltd, British Pharmacological Society and American Society for Pharmacology and Experimental Therapeutics.)

The translocator protein (TSPO) is a target for the development of neuroinflammation imaging agents. Clinical translation of TSPO PET ligands, such as [ 11 C]DPA-713, has been hampered by the presence of a common polymorphism (A147T TSPO), at which all second-generation TSPO ligands lose affinity. Little is known about what drives binding at A147T compared to WT TSPO. This study aimed to identify moieties in DPA-713, and related derivatives, that influence binding at A147T compared to WT TSPO. We found changes to the nitrogen position and number in the heterocyclic core influences affinity to WT and A147T to a similar degree. Hydrogen bonding groups in molecules with an indole core improve binding at A147T compared to WT, a strategy that generated compounds that possess up to ten-times greater affinity for A147T. These results should inform the future design of compounds that bind both A147T and WT TSPO for use in neuroinflammation imaging., (This journal is © The Royal Society of Chemistry 2020.)

Background and Aims: The Psychoactive Surveillance Consortium and Analysis Network (PSCAN) is a national network of academic emergency departments (ED), analytical toxicologists and pharmacologists that collects clinical data paired with biological samples to identify and improve treatments of medical conditions arising from use of new psychoactive substances (NPS). The aim of this study was to gather clinical data with paired drug identification from NPS users who presented to EDs within PSCAN during its first year (2016-17)., Design: Observational study involving patient records and biological samples., Setting: Seven academic emergency medical centers across the United States., Participants: ED patients (n = 127) > 8 years of age with possible NPS use who were identified and enrolled in PSCAN by clinical providers or research personnel., Measurements: Clinical signs, symptoms and treatments were abstracted from the patients' health records. Biological samples were collected from leftover urine, serum and whole blood. Biological and drug samples, when available, were tested for drugs and drug metabolites via liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF/MS)., Findings: Patients in whom synthetic opioids were detected (n = 9) showed higher rates of intubation (four of nine), impaired mental status (four of nine) and respiratory acidosis (five of nine) compared with the rest of the cohort (nine of 118, P-value < 0.05). Patients in whom synthetic cannabinoid (SC) were found (n = 27) had lower median diastolic blood pressures (70.5 versus 77 mmHg, P = 0.046) compared with the rest of the cohort. In 64 cases of single drug ingestion, benzodiazepines were administered in 25 cases and considered effective by the treating physician in 21 (84%) cases., Conclusions: During its first year of operation, the Psychoactive Surveillance Consortium and Analysis Network captured clinical data on new classes of drugs paired with biological samples over a large geographical area in the United States. Synthetic cannabinoids were the most common new psychoactive drug identified. Synthetic opioids were associated with a high rate of intubation and respiratory acidosis., (© 2019 Society for the Study of Addiction.)

We describe the validation of a method for the simultaneous analysis of 29 synthetic cannabinoids (SCs) and metabolites, 4 amphetamines, and 2 cannabinoids in human whole blood. This method enables one analysis to cover what previously required multiple analyses for these classic and novel drugs-of-abuse with diverse physicochemical properties. The scope of targeted analytes was based on the most prevalent drugs-of-abuse and SCs encountered at the New Zealand border in 2017 and included parent compounds and metabolites belonging to the indole and indazole carboxamide, quinolinyl indole carboxylate, and naphthoylindole classifications. Samples were prepared by supported-liquid-extraction (SLE) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis with positive electrospray ionization (ESI). The method was validated with respect to selectivity, matrix effects, process efficiency, sensitivity, repeatability, extract stability, and carryover for qualitative confirmation. Linearity as well as accuracy and precision data at target decision concentrations were also evaluated. The limits of detection and confirmation ranged from 0.1 to 6.0 ng/mL and 1.0 to 6.0 ng/mL, respectively. The described method was successfully applied to the analysis of 564 ante- and post-mortem blood samples in 2018. There were 132 cases (23%) with positive findings of at least one SC, with the five most commonly detected SCs being AMB-FUBINACA and/or acid (61%), 5F-ADB and/or acid (40%), ADB-FUBINACA (11%), 5F-MDMB-PICA acid (6%), and MDMB-FUBINACA acid (6%). The results also demonstrate the predominant presence of metabolites at higher levels than the unchanged parent SCs in blood, highlighting the need to maintain forensic screening methods capable of the simultaneous detection of both parent compounds and metabolites., (© 2019 John Wiley & Sons, Ltd.)

Background and Purpose: The morbidity and mortality associated with recreational use of synthetic cannabinoid receptor agonists (SCRAs) may reflect strong activation of CB 1 receptors and is a major health concern. The properties of SCRA at CB 1 receptors are not well defined. Here we have developed an assay to determine acute CB 1 receptor efficacy using receptor depletion with the irreversible CB 1 receptor antagonist AM6544, with application of the Black and Leff operational model to calculate efficacy., Experimental Approach: Receptor depletion in mouse AtT-20 pituitary adenoma cells stably expressing human CB 1 receptors was achieved by pretreatment of cells with AM6544 (10 μM, 60 min). The CB 1 receptor-mediated hyperpolarisation of AtT-20 cells was measured using fluorescence-based membrane potential dye. From data fit to the operational model, the efficacy (τ) and affinity (K A ) parameters were obtained for each drug., Key Results: AM6544 did not affect the potency or maximal effect of native somatostatin receptor-induced hyperpolarization. The τ value of ∆ 9 -THC was 80-fold less than the reference CB receptor agonist CP55940 and 260-fold less than the highest efficacy SCRA, 5F-MDMB-PICA. The operational efficacy of SCRAs ranged from 233 (5F-MDMB-PICA) to 28 (AB-PINACA), with CP55940 in the middle of the efficacy rank order. There was no correlation between the τ and K A values., Conclusions and Implications: All SCRAs tested showed substantially higher efficacy at CB 1 receptors than ∆ 9 -THC, which may contribute to the adverse effects seen with these drugs but not ∆ 9 -THC., (© 2019 The British Pharmacological Society.)

Cannabis sativa produces a complex mixture of many bioactive molecules including terpenophenolic compounds known as phytocannabinoids. Phytocannabinoids come in neutral forms (e.g., Δ 9 -tetrahydrocannabinol, THC; cannabidiol, CBD; etc.) or as acid precursors, which are dominant in the plant (e.g., Δ 9 -tetrahydrocannabinolic acid, THCA; cannabidiolic acid, CBDA; etc.). There is increasing interest in unlocking the therapeutic applications of the phytocannabinoid acids; however, the present understanding of the basic pharmacology of phytocannabinoid acids is limited. Herein the brain and plasma pharmacokinetic profiles of CBDA, THCA, cannabichromenic acid (CBCA), cannabidivarinic acid (CBDVA), cannabigerolic acid (CBGA), and cannabigerovarinic acid (CBGVA) were examined following intraperitoneal administration in mice. Next it was examined whether CBDA was anticonvulsant in a mouse model of Dravet syndrome ( Scn1a RX/+ mice). All the phytocannabinoid acids investigated were rapidly absorbed with plasma t max values of between 15 and 45 min and had relatively short half-lives (<4 h). The brain-plasma ratios for the acids were very low at ≤0.04. However, when CBDA was administered in an alternate Tween 80-based vehicle, it exhibited a brain-plasma ratio of 1.9. The anticonvulsant potential of CBDA was examined using this vehicle, and it was found that CBDA significantly increased the temperature threshold at which the Scn1a RX/+ mice had a generalized tonic-clonic seizure.

Cannabinoid receptors type 1 (CB 1 ) and type 2 (CB 2 ) are promising targets for a number of diseases, including obesity, neuropathic pain, and multiple sclerosis, among others. Upon ligand-mediated activation of these receptors, multiple receptor conformations could be stabilized, resulting in a complex pattern of possible intracellular effects. Although numerous compounds have been developed and widely used to target cannabinoid receptors, their mode of action and signaling properties are often only poorly characterized. From a drug development point of view, unraveling the underlying complex signaling mechanism could offer the possibility to generate medicines with the desired therapeutic profile. Recently, an increased interest has emerged for the development of agonists that are signaling pathway-selective and thereby do not evoke on-target adverse effects. This phenomenon, in which specific pathways are preferred upon receptor activation by certain ligands, is also known as 'biased signaling'. For a particular group of cannabinoid receptor ligands (i.e. CB 1 /CB 2 agonists), namely the synthetic cannabinoid receptor agonists (SCRAs), the research on biased signaling is still in its infancy and interesting outcomes are only recently being revealed. Therefore, this review aims at providing insights into the recent knowledge about biased agonism mediated by SCRAs so far. In addition, as these outcomes are obtained using a distinct panel of functional assays, the accompanying difficulties and challenges when comparing functional outcomes are critically discussed. Finally, some guidance on the conceptualization of ideal in vitro assays for the detection of SCRA-mediated biased agonism, which is also relevant for compounds belonging to other chemical classes, is provided., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Recreational consumption of synthetic cannabinoid receptor agonists (SCRAs) is a growing crisis in public health in many parts of the world. AMB-FUBINACA is a member of this class of drugs and is responsible for a large proportion of SCRA-related toxicity both in New Zealand and internationally. Strikingly, little is currently known about the mechanisms by which SCRAs exert toxic effects or whether their activity through the CB 1 cannabinoid receptor (the mediator of cannabinoid-related psychoactivity) is sufficient to explain clinical observations. The current study therefore set out to perform a basic molecular pharmacology characterization of AMB-FUBINACA (in comparison to traditional research cannabinoids CP55,940, WIN55,212-2, and Δ 9 -THC) in fundamental pathways of receptor activity, including cAMP inhibition, pERK activation, ability to drive CB 1 internalization, and ability to induce translocation of β-arrestins-1 and -2. Activity pathways were then compared by operational analysis to indicate whether AMB-FUBINACA may be a biased ligand. Results revealed that AMB-FUBINACA is highly efficacious and potent in all pathways assayed. However, surprisingly, bias analysis suggested that Δ 9 -THC, not AMB-FUBINACA, may be a biased ligand, with it being less active in both arrestin pathways than predicted by the activity of the other ligands tested. These data may help predict molecular characteristics of SCRAs. However, more research is required to determine whether these molecular effects manifest in toxicity at tissue/system level.

5F-PY-PICA and 5F-PY-PINACA are pyrrolidinyl 1-(5-fluoropentyl)ind (az)ole-3-carboxamides identified in 2015 as putative synthetic cannabinoid receptor agonist (SCRA) new psychoactive substances (NPS). 5F-PY-PICA, 5F-PY-PINACA, and analogs featuring variation of the 1-alkyl substituent or contraction, expansion, or scission of the pyrrolidine ring were synthesized and characterized by nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QTOF-MS). In competitive binding experiments against HEK293 cells expressing human cannabinoid receptor type 1 (hCB 1 ) or type 2 (hCB 2 ), all analogs showed minimal affinity for CB 1 (pK i  < 5), although several demonstrated moderate CB 2 binding (pK i 5.45-6.99). In fluorescence-based membrane potential assays using AtT20-hCB 1 or -hCB 2 cells, none of the compounds (at 10 μM) produced an effect >50% of the classical cannabinoid agonist CP55,940 (at 1 μM) at hCB 1 , although several showed slightly higher relative efficacy at hCB 2 . Expansion of the pyrrolidine ring of 5F-PY-PICA to an azepane (8) conferred the greatest hCB 2 affinity (pK i 6.99) and activity (pEC 50 7.54, E max 72%) within the series. Unlike other SCRA NPS evaluated in vivo using radio biotelemetry, 5F-PY-PICA and 5F-PY-PINACA did not produce cannabimimetic effects (hypothermia, bradycardia) in mice at doses up to 10 mg/kg., (© 2019 John Wiley & Sons, Ltd.)

Synthetic cannabinoid receptor agonists (SCRAs) are the largest class of new psychoactive substances (NPS). New examples are detected constantly, and some are associated with a series of adverse effects, including seizures. CUMYL-4CN-BINACA (1-(4-cyanobutyl)- N -(2-phenylpropan-2-yl)indazole-3-carboxamide) is structurally related to potent, cumylamine-derived SCRAs such as 5F-CUMYL-PINACA, but is unusual due to a terminal aliphatic nitrile group not frequently encountered in SCRAs or pharmaceuticals. We report here that CUMYL-4CN-BINACA is a potent CB 1 receptor agonist ( K i = 2.6 nM; EC 50 = 0.58 nM) that produces pro-convulsant effects in mice at a lower dose than reported for any SCRA to date (0.3 mg/kg, i.p). Hypothermic and pro-convulsant effects in mice could be reduced or blocked, respectively, by pretreatment with CB 1 receptor antagonist SR141716, pointing to at least partial involvement of CB 1 receptors in vivo . Pretreatment with CB2 receptor antagonist AM-630 had no effect on pro-convulsant activity. The pro-convulsant properties and potency of CUMYL-4CN-BINACA may underpin the toxicity associated with this compound in humans.

Cannabis ( Cannabis sativa) is the most widely used illicit drug in the world, with an estimated 192 million users globally. The main psychoactive component of cannabis is (-)- trans-Δ 9 -tetrahydrocannabinol (Δ 9 -THC), a compound with a diverse range of pharmacological actions. The unique and distinctive intoxication caused by Δ 9 -THC primarily reflects partial agonist action at central cannabinoid type 1 (CB 1 ) receptors. Δ 9 -THC is an approved therapeutic treatment for a range of conditions, including chronic pain, chemotherapy-induced nausea and vomiting, and multiple sclerosis, and is being investigated in indications such as anorexia nervosa, agitation in dementia, and Tourette's syndrome. It is available as a regulated pharmaceutical in products such as Marinol, Sativex, and Namisol as well as in an ever-increasing range of unregistered medicinal and recreational cannabis products. While cannabis is an ancient medicament, contemporary use is embroiled in legal, scientific, and social controversy, much of which relates to the potential hazards and benefits of Δ 9 -THC itself. Robust contemporary debate surrounds the therapeutic value of Δ 9 -THC in different diseases, its capacity to produce psychosis and cognitive impairment, and the addictive and "gateway" potential of the drug. This review will provide a profile of the chemistry, pharmacology, and therapeutic uses of Δ 9 -THC as well as the historical and societal import of this unique, distinctive, and ubiquitous psychoactive substance.

Neuropathic pain is caused by a lesion or dysfunction in the nervous system, and it may arise from illness, be drug-induced or caused by toxin exposure. Since the discovery of two G-protein-coupled cannabinoid receptors (CB 1 and CB 2 ) nearly three decades ago, there has been a rapid expansion in our understanding of cannabinoid pharmacology. This is currently one of the most active fields of neuropharmacology, and interest has emerged in developing cannabinoids and other small molecule modulators of CB 1 and CB 2 as therapeutics for neuropathic pain. This short review article provides an overview of the chemotypes currently under investigation for the development of novel neuropathic pain treatments targeting CB 1 receptors.

Synthetic cannabinoid receptor agonists (SCRAs) are a dynamic class of new psychoactive substances (NPS), with novel chemotypes emerging each year. Following the putative detection of 5F-CUMYL-P7AICA in Australia in 2016, the scaffold-hopping SCRAs 5F-CUMYL-PICA, 5F-CUMYL-PINACA, and 5F-CUMYL-P7AICA were synthesized and characterized by nuclear magnetic resonance (NMR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-quadrupole time-of-flight-MS (LC-QTOF-MS). Since little is known of the pharmacology of 7-azaindole SCRAs like 5F-CUMYL-P7AICA, the binding affinities and functional activities of all compounds at cannabinoid type 1 and type 2 receptors (CB 1 and CB 2 , respectively) were assessed using tritiated radioligand competition experiments and fluorescence-based plate reader membrane potential assays. Despite CB 1 binding affinities differing by over two orders of magnitude (K i  = 2.95-174 nM), all compounds were potent and efficacious CB 1 agonists (EC 50  = 0.43-4.7 nM), with consistent rank order for binding and functional activity (5F-CUMYL-PINACA >5F-CUMYL-PICA >5F-CUMYL-P7AICA). Additionally, 5F-CUMYL-P7AICA was found to exert potent cannabimimetic effects in mice, inducing hypothermia (6°C, 3 mg/kg) through a CB 1 -dependent mechanism., (© 2018 John Wiley & Sons, Ltd.)

Cannabis elicits its mood-enhancing and analgesic effects through the cannabinoid receptor 1 (CB1), a G protein-coupled receptor (GPCR) that signals primarily through the adenylyl cyclase-inhibiting heterotrimeric G protein G i . Activation of CB1-G i signaling pathways holds potential for treating a number of neurological disorders and is thus crucial to understand the mechanism of G i activation by CB1. Here, we present the structure of the CB1-G i signaling complex bound to the highly potent agonist MDMB-Fubinaca (FUB), a recently emerged illicit synthetic cannabinoid infused in street drugs that have been associated with numerous overdoses and fatalities. The structure illustrates how FUB stabilizes the receptor in an active state to facilitate nucleotide exchange in G i . The results compose the structural framework to explain CB1 activation by different classes of ligands and provide insights into the G protein coupling and selectivity mechanisms adopted by the receptor., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Rationale: A novel benzimidazole compound ZLN005 was previously identified as a transcriptional activator of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) in certain metabolic tissues. Upregulation of PGC-1α by ZLN005 has been shown to have a beneficial effect in a diabetic mouse model and in a coronary artery disease model in vitro. ZLN005 could also have therapeutic potential in neurodegenerative diseases involving down-regulation of PGC-1α. Given the phenotypic efficacy of ZLN005 in several animal models of human disease, its metabolic profile was investigated to guide the development of novel therapeutics using ZLN005 as the lead compound., Methods: ZLN005 was incubated with both rat and human liver microsomes and S9 fractions to identify in vitro metabolites. Urine from rats dosed with ZLN005 was used to identify in vivo metabolites. Extracted metabolites were analyzed by liquid chromatography/tandem mass spectrometry (LC/MS/MS) using a hybrid linear ion trap triple quadrupole mass spectrometer in full scan, enhanced product ion scan, neutral loss scan and precursor scan modes. Metabolites in plasma and brain of ZLN005-treated rats were also profiled using multiple reaction monitoring., Results: Identified in vitro transformations of ZLN005 include mono- and dihydroxylation, further oxidation to carboxylic acids, and mono-O-glucuronide and sulfate conjugation to hydroxy ZLN005 as well as glutathione conjugation. Identified in vivo metabolites are mainly glucuronide and sulfate conjugates of dihydroxyl, carboxyl, and hydroxy acid of the parent compound. The parent compound as well as several major phase I metabolites were found in rat plasma and brain., Conclusions: Using both in vitro and in vivo methods, we elucidated the metabolic pathway of ZLN005. Phase I metabolites with hydroxylation and carboxylation, as well as phase II metabolites with glucuronide, sulfate and glutathione conjugation, were identified., (Copyright © 2018 John Wiley & Sons, Ltd.)

Background: Use of new psychoactive substances (NPS) has increased over the last decade. During this period, variability of both clinical presentations and chemical compositions of these compounds has increased. Synthetic cannabinoids (SCs) are the most commonly used NPS and there are more than 100 documented unique molecules in this class. "Black Mamba", often associated to ADB-FUBINACA, is the most commonly used SC in Colorado. It has been linked to kidney injury, myocardial toxicity, seizures, and death., Objectives: We aim to identify the chemical constituents and quantification of eight cases of reported "Black Mamba" use in order to further understand the clinical variability in patients presenting for emergency stabilization., Methods: We report data from eight cases of reported "Black Mamba" use prospectively captured through the Colorado site of the Psychoactive Surveilance Consortium and Analysis Network (P SCAN). P SCAN is a geographically representative group of academic hospitals that capture clinical presentation, outcome, and biologic samples from patients that present for emergency stabilization following NPS use. Serum and urine samples were analyzed and quantified by liquid chromatography-quadrupole time-of-flight mass spectrometry after a qualitative screen for over 600 unique NPS compounds., Results: In the reported eight cases, the median age was 28 years old. There were four male and four females. Four patients had agitation/delirium and four patients had chest pain. Normal saline, benzodiazepines and ondansetron were the common treatment provided in the emergency department (ED). Two patients were discharged from the ED and six patients being admitted for emergency observation with a median length of stay (LOS) of six hours. No deaths were reported. Confirmatory testing revealed that only five patients (62.5%) had SCs found in blood or urine samples. Cocaine, NRG-3, 3-methoxyphencyclidine hydrochloride (MeO-PCP), and methamfetamine were identified in other presentations., Conclusions: The wide range of clinical presentations from "Black Mamba" use may be explained by the wide variability of chemical constituents found by laboratory analysis.

Synthetic cannabinoids are the largest and most structurally diverse class of new psychoactive substances, with manufacturers often using isomerism to evade detection and circumvent legal restriction. The regioisomeric methoxy- and fluorine-substituted analogs of SDB-006 (N-benzyl-1-pentyl-1H-indole-3-carboxamide) were synthesized and could not be differentiated by gas chromatography-mass spectrometry (GC-MS), but were distinguishable by liquid chromatography-quadrupole time-of-flight-MS (LC-QTOF-MS). In a fluorescence-based plate reader membrane potential assay, SDB-006 acted as a potent agonist at human cannabinoid receptors (CB 1 EC 50 = 19 nM). All methoxy- and fluorine-substituted analogs showed reduced potency compared to SDB-006, although the 2-fluorinated analog (EC 50 = 166 nM) was comparable to known synthetic cannabinoid RCS-4 (EC 50 = 146 nM). Using biotelemetry in rats, SDB-006 and RCS-4 evoked comparable reduction in body temperature (~0.7°C at a dose of 10 mg/kg), suggesting lower potency than the recent synthetic cannabinoid AB-CHMINACA (>2°C, 3 mg/kg)., (Copyright © 2018 John Wiley & Sons, Ltd.)

Synthetic cannabinoid receptor agonists (SCRAs) have proliferated as new psychoactive substances (NPS) over the past decade. Relative to other classes of NPS, SCRAs are structurally heterogeneous; however, most SCRAs act as potent, high-efficacy agonists of cannabinoid type 1 and type 2 receptors (CB 1 and CB 2 , respectively). Characterization of the pharmacology and toxicology of these substances is hindered by the dynamic nature of the SCRA marketplace. Beyond basic pharmacological profiling at CB 1 and CB 2 receptors, very little is known about the acute or chronic effects of SCRAs. Many of the effects of SCRAs are qualitatively similar to those of the Δ 9 -tetrahydrocannabinol (Δ 9 -THC) found in cannabis. However, unlike Δ 9 -THC, SCRAs are frequently associated with serious adverse effects, including cardiotoxicity, nephrotoxicity, and death. This chapter will provide an overview of the structure and function of the primary target for SCRAs, the CB 1 receptor, and survey the structure-activity relationships of the historical SCRAs that served as templates for the earliest generations of NPS.