JWH-018 in rhesus monkeys: differential antagonism of discriminative stimulus, rate-decreasing, and hypothermic effects

Unveiling the toxicity of JWH-018 and JWH-019: Insights from behavioral and molecular studies in vivo and vitro

Due to the structural diversity and rapid prevalence of synthetic cannabinoids (SCs) in the market, the information linking the chemical structure of SCs to their toxicity remains scant, despite emerging in the 1970s. In the present study, we aimed to investigate the toxicity and underlying mechanisms of indole SCs JWH-018 and JWH-019 in mice (C57BL/6, male, 6-8 weeks old), zebrafish (AB strain, male, 4-5 months old) and modified human embryonic kidney (HEK) 293 T cells, using behavioral, pharmacokinetic, pharmacological approaches, and molecular docking. JWH-018 induced time- and dose-dependent cannabinoid-like effects in mice (administration dosages: 0.02, 0.1, and 0.5 mg/kg, i.p.), and yielded dose-dependent anxiogenic effects and lower aggression behavior in zebrafish (administration dosages: 0.01, 0.05, and 0.25 µg/g, i.p.), unlike JWH-019. These effects were blocked by the selective cannabinoid receptor 1 (CB1R) antagonist AM251. JWH-018, but not JWH-019, activated the CB1R-dependent extracellular signal-regulated kinase 1 and 2 (ERK1/2) pathway in vivo and in vitro. Molecular docking identified essential residues PHE268, PHE170, and TRP279 within CB1R as pivotal contributors to enhancing receptor-ligand associations. While both drugs had a similar binding pattern with shared linker binding pockets in CB1R, there were still differences in their spatial conformation. These findings shed light on the molecular pharmacology and activation mechanism of SCs for CB1R and should guide further research into the mechanisms underlying their deleterious effects in humans.

Effects of cannabinoid agonists and antagonists in male rats discriminating the synthetic cannabinoid AM2201

The synthetic forms of delta-9-tetrahydrocannabinol (Δ9-THC), dronabinol or nabilone, have been approved to treat several indications. However, due to safety concerns their clinical utility remains limited. Consequently, there is a need for developing cannabinoid (CB) ligands that display better behavioral pharmacological profiles than Δ9-THC. Here, we utilized drug discrimination methods to compare the interoceptive effects of CB ligands that vary in potency, efficacy, and selectivity at the CB receptors, including two ligands, AM411 and AM4089, that show CB1 partial agonist-like actions in vitro. Male rats were trained to discriminate 0.1 mg/kg AM2201 from saline under a fixed-ratio (FR) 10 response schedule of food reinforcement. After establishing AM2201's discriminative-stimulus effects, pretreatment tests with the CB1 antagonist/inverse agonist rimonabant blocked AM2201's effects, whereas the peripherally-restricted antagonist AM6545 had no effect. Next, the generalization profiles of AM411 and AM4089 with CB1 full agonists (JWH-018, CP-55,940, AM8936), partial agonist (Δ9-THC), and non-cannabinoids (fentanyl, atropine) were compared. The CBs either fully (AM2201, CP-55,940, JWH-018, AM8936, Δ9-THC) or partially (AM411, AM4089) substituted for AM2201, whereas fentanyl and atropine did not produce AM2201-like effects. All CB drugs were more potent than Δ9-THC and correlation analysis confirmed that the relative behavioral potencies of CBs corresponded strongly with their relative affinities at the CB1 but not CB2 receptors. Together, our results further demonstrate that AM411 and AM4089 exhibit better pharmacological profiles compared to Δ9-THC, in that they are more potent and display in vivo partial agonist-like actions that are centrally mediated via CB1 receptors.

Functional consequences of short-term exposure to opioids versus cannabinoids in nonhuman primates

Opioids provide pain relief but are associated with several adverse effects. Researchers are exploring cannabis-based medicine as an alternative. However, little is known about the tendency for physical dependence on cannabinoids in comparison with that on opioids in primates. The aim of this study was to compare the potency of heroin and delta-9-tetrahydrocannabinol (THC) in eliciting analgesic effects and the development of physical dependence between opioids and cannabinoids in both male and female rhesus monkeys. Systemic administration of either heroin (0.03-0.18 mg/kg) or THC (0.3-1.8 mg/kg) in a dose-dependent manner produced antinociceptive effects against an acute thermal nociceptive stimulus. The μ-opioid receptor antagonist naltrexone (0.01 mg/kg) and the cannabinoid receptor antagonist SR141716A (0.3 mg/kg) produced the same degree of rightward shift in the dose-response curves for heroin- and THC-induced antinociception, respectively. Monkeys implanted with telemetry devices were subjected to short-term repeated administrations (two injections per day for 1-3 days) of either heroin (0.18 mg/kg), morphine (1.8 mg/kg), THC (1.8 mg/kg), or CP 55,940 (0.032 mg/kg). Administration of naltrexone (0.01 mg/kg) increased respiration, heart rate, and blood pressure in heroin- or morphine-treated monkeys. In contrast, administration of SR141716A (0.3 mg/kg) did not cause a significant change in these physiological parameters in THC- or CP 55,940-treated monkeys. Additionally, morphine, but not CP 55,940, enhanced the monkeys' hypersensitivity to the algogen capsaicin. Collectively, these results demonstrate that in nonhuman primates, both opioids and cannabinoids exert comparable antinociception; however, physical dependence on opioids, but not cannabinoids, at their antinociceptive doses, occurs following short-term exposures.

In Vivo Bio-Activation of JWH-175 to JWH-018: Pharmacodynamic and Pharmacokinetic Studies in Mice

3-(1-Naphthalenylmethyl)-1-pentyl-1H-indole (JWH-175) is a synthetic cannabinoid illegally marketed for its psychoactive cannabis-like effects. This study aimed to investigate and compare in vitro and in vivo pharmacodynamic activity of JWH-175 with that of 1-naphthalenyl (1-pentyl-1H-indol-3-yl)-methanone (JWH-018), as well as evaluate the in vitro (human liver microsomes) and in vivo (urine and plasma of CD-1 male mice) metabolic profile of JWH-175. In vitro binding studies showed that JWH-175 is a cannabinoid receptor agonist less potent than JWH-018 on mouse and human CB1 and CB2 receptors. In agreement with in vitro data, JWH-175 reduced the fESPS in brain hippocampal slices of mice less effectively than JWH-018. Similarly, in vivo behavioral studies showed that JWH-175 impaired sensorimotor responses, reduced breath rate and motor activity, and increased pain threshold to mechanical stimuli less potently than JWH-018. Metabolic studies demonstrated that JWH-175 is rapidly bioactivated to JWH-018 in mice blood, suggesting that in vivo effects of JWH-175 are also due to JWH-018 formation. The pharmaco-toxicological profile of JWH-175 was characterized for the first time, proving its in vivo bio-activation to the more potent agonist JWH-018. Thus, it highlighted the great importance of investigating the in vivo metabolism of synthetic cannabinoids for both clinical toxicology and forensic purposes.

Self-administration of inhaled delta-9-tetrahydrocannabinol and synthetic cannabinoids in non-human primates

Cannabis and synthetic cannabinoids are abused in spite of possible adverse health consequences. The current study investigated the reinforcing effects of an ecologically relevant mode of administration (inhalation) of delta-9-tetrahydrocannabinol (THC), the primary psychoactive component of cannabis, and three synthetic cannabinoids detected in synthetic cannabinoid products (JWH-018, JWH-073, and HU-210) in non-human primates (NHPs). Male and female (N = 4 each) rhesus macaques were trained to inhale warm air via a metal stem to receive a candy reinforcer, an alcohol aerosol vehicle was then paired with the candy. Dose-dependent responding for inhaled aerosols of THC (2.0-16.0 μg/kg/inhalation), JWH-018 (0.2-1.6 μg/kg/inhalation), JWH-073 (2.0-8.0 μg/kg/inhalation), and HU-210 (1.0-8.0 μg/kg/inhalation) was established using a fixed-ratio five schedule of reinforcement and compared to vehicle (alcohol) self-administration. Dose-dependent responding for inhaled heroin (25.0-100.0 μg/kg/inhalation), a known reinforcer in NHPs, was also established. Responding approximated vehicle levels for many drug doses tested, but at least half of the monkeys responded for ≥ one dose of each cannabinoid and heroin above vehicle, with the exception of THC. Drug deliveries calculated as percent vehicle followed a prototypical inverted-U shaped dose-response curve for cannabinoids and heroin except for THC and JWH-018 (in males). Grouped data according to sex demonstrated that peak percent of vehicle reinforcers earned for THC was greater in males than females, whereas peak percent of vehicle reinforcers earned for JWH-018, HU-210, and heroin were greater in females than males. These findings indicate minimal reinforcing effects of CB1 receptor agonists when self-administered by NHPs via aerosol inhalation. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

QSAR Model for Predicting the Cannabinoid Receptor 1 Binding Affinity and Dependence Potential of Synthetic Cannabinoids

In recent years, there have been frequent reports on the adverse effects of synthetic cannabinoid (SC) abuse. SCs cause psychoactive effects, similar to those caused by marijuana, by binding and activating cannabinoid receptor 1 (CB1R) in the central nervous system. The aim of this study was to establish a reliable quantitative structure–activity relationship (QSAR) model to correlate the structures and physicochemical properties of various SCs with their CB1R-binding affinities. We prepared tetrahydrocannabinol (THC) and 14 SCs and their derivatives (naphthoylindoles, naphthoylnaphthalenes, benzoylindoles, and cyclohexylphenols) and determined their binding affinity to CB1R, which is known as a dependence-related target. We calculated the molecular descriptors for dataset compounds using an R/CDK (R package integrated with CDK, version 3.5.0) toolkit to build QSAR regression models. These models were established, and statistical evaluations were performed using the mlr and plsr packages in R software. The most reliable QSAR model was obtained from the partial least squares regression method via Y-randomization test and external validation. This model can be applied in vivo to predict the addictive properties of illicit new SCs. Using a limited number of dataset compounds and our own experimental activity data, we built a QSAR model for SCs with good predictability. This QSAR modeling approach provides a novel strategy for establishing an efficient tool to predict the abuse potential of various SCs and to control their illicit use.

Interactions between opioids and cannabinoids: Economic demand for opioid/cannabinoid mixtures

BACKGROUND

Opioid abuse remains a significant public health challenge. With continuing emergence of novel psychoactive substances (e.g., synthetic cannabinoids found in "K2" or "spice" preparations), the co-administration of opioids and other novel drugs is likely to become more prevalent, which might increase the risk for abuse and other adverse effects. This study examined whether the synthetic cannabinoid receptor agonist JWH-018 alters the reinforcing effectiveness of the mu opioid receptor agonist remifentanil in rhesus monkeys (n = 4) using economic demand analyses.

METHODS

Lever presses delivered intravenous infusions of a drug or drug mixture according to a fixed-ratio schedule. For each condition, the ratio progressively increased in quarter-log unit steps across sessions yielding a demand curve: consumption (infusions obtained) was plotted as a function of price (fixed-ratio value).

RESULTS

When available alone, remifentanil (0.00032 mg/kg/infusion) occasioned the highest consumption at the lowest cost and highest essential value, while JWH-018 (0.0032 mg/kg/infusion) alone occasioned lower unconstrained demand and essential value. Unconstrained demand for a mixture of remifentanil and JWH-018 was lower than for remifentanil alone, but essential value of the mixture was not significantly different from that of remifentanil alone.

CONCLUSION

These data indicate that synthetic cannabinoids such as JWH-018 might alter some aspects of opioid self-administration (i.e., decreased consumption at the lowest price) but do not enhance reinforcing effectiveness as measured by sensitivity of consumption to increasing costs. Opioid/cannabinoid mixtures do not appear to have greater or lesser abuse potential compared with opioids alone.

Post-Mortem Toxicology: A Systematic Review of Death Cases Involving Synthetic Cannabinoid Receptor Agonists

BACKGROUND

Synthetic cannabinoid receptor agonists (SCRAs) have become the largest group of new psychoactive substances monitored by the European Union Early Warning System. Despite the wide diffusion on the market, data regarding effects, toxicities, and mechanisms as well as toxic/lethal doses are still scarce.

METHODS

A comprehensive literature search for articles published up to January 2019 was performed in multiple electronic databases. Only cases of death in which toxicological analyses revealed the presence of SCRAs in blood or urine and at least an external examination was performed, including those occurred in emergency departments, were included.

RESULTS

Of 380 studies identified, 354 were excluded, while 8 additional manuscripts were included through the screening of relevant references cited in the selected articles. A total number of 34 manuscripts (8 case series and 26 case reports) were included.

CONCLUSIONS

Typical toxic ranges for SCRAs have not been so far identified, and the results of toxicological analyses should be interpreted with caution. In death cases involving SCRAs, a thorough post-mortem examination is a prerequisite to assess the role of the substance use in the deceased and to identify a probable mechanism of death. Even after a comprehensive analysis of clinical, circumstantial, toxicological, and autoptic data, the cause and manner of death remain unclear in some cases.

Δ9-Tetrahydrocannabinol-like discriminative stimulus effects of five novel synthetic cannabinoids in rats

RATIONALE AND OBJECTIVES

Novel synthetic cannabinoid compounds continue to appear in the market advertised as legal alternatives to marijuana and the older synthetic cannabinoid compounds which are now controlled substances. Most of these newer compounds have been found to act at CB1 receptors, so the purpose of this study was to study the abuse liability of these compounds.

METHODS

Five of these compounds (BB-22, FUB-PB-22, 5F-AMB, NM2201, and MAB-CHMINACA) were tested for their ability to produce discriminative stimulus effects similar to Δ⁹-tetrahydrocannabinol (Δ⁹-THC) in rats. The ability of the CB1 receptor inverse agonist rimonabant to antagonize the discriminative stimulus effects of the five test compounds was also tested.

RESULTS

All five of the test compounds fully substituted for the discriminative stimulus effects of Δ⁹-THC at some dose, although MAB-CHMINACA produced an inverted U-shaped dose effect. Rimonabant fully antagonized the Δ⁹-THC-like discriminative stimulus effects of BB-22, 5F-AMB, NM2201, and MAB-CHMINACA but only reduced the effects of FUB-PB-22 to 40-50 % of Δ⁹-THC-appropriate responding.

CONCLUSIONS

These findings suggest that all five of the test compounds produced Δ⁹-THC-like effects and will likely have abuse liability similar to that of the controlled cannabinoid compounds.

Pro-psychotic effects of synthetic cannabinoids: interactions with central dopamine, serotonin, and glutamate systems

An association between marijuana use and schizophrenia has been noted for decades, and the recent emergence of high-efficacy synthetic cannabinoids (SCBs) as drugs of abuse has lead to a growing number of clinical reports of persistent psychotic effects in users of these substances. The mechanisms underlying SCB-elicited pro-psychotic effects is unknown, but given the ubiquitous neuromodulatory functions of the endocannabinoid system, it seems likely that agonist actions at cannabinoid type-1 receptors (CB1Rs) might modulate the functions of other neurotransmitter systems known to be involved in schizophrenia. The present review surveys what is currently known about the interactions of CB1Rs with dopamine, serotonin, and glutamate systems, because all three of those neurotransmitters are well-established in the pathophysiology of schizophrenia and psychosis. Identification of molecular mechanisms underlying the pro-psychotic effects of SCB drugs of abuse may establish certain classes of these substances as particularly dangerous, guiding regulations to control availability of these drugs. Likewise, an understanding of the pharmacological interactions which lead to schizophrenia and psychosis subsequent to SCB exposure might guide the development of novel therapies to treat afflicted users.

Discriminative Stimulus Properties of Phytocannabinoids, Endocannabinoids, and Synthetic Cannabinoids

Psychoactive cannabinoids from the marijuana plant (phytocannabinoids), from the body (endocannabinoids), and from the research lab (synthetic cannabinoids) produce their discriminative stimulus effects by stimulation of CB1 receptors in the brain. Early discrimination work with phytocannabinoids confirmed that Δ9-tetrahydrocannabinol (Δ9-THC) is the primary psychoactive constituent of the marijuana plant, with more recent work focusing on characterization of the contribution of the major endocannabinoids, anandamide and 2-arachidonoylglycerol (2-AG), to Δ9-THC-like internal states. Collectively, these latter studies suggest that endogenous increases in both anandamide and 2-AG seem to be optimal for mimicking Δ9-THC's discriminative stimulus effects, although suprathreshold concentrations of anandamide also appear to be Δ9-THC-like in discrimination assays. Recently, increased abuse of synthetic cannabinoids (e.g., "fake marijuana") has spurred discrimination studies to inform regulatory authorities by predicting which of the many synthetic compounds on the illicit market are most likely to share Δ9-THC's abuse liability. In the absence of a reliable model of cannabinoid self-administration (specifically, Δ9-THC self-administration), cannabinoid discrimination represents the most validated and pharmacologically selective animal model of an abuse-related property of cannabinoids - i.e., marijuana's subjective effects. The influx of recent papers in which cannabinoid discrimination is highlighted attests to its continued relevance as a valuable method for scientific study of cannabinoid use and abuse.

Apparent Affinity Estimates and Reversal of the Effects of Synthetic Cannabinoids AM-2201, CP-47,497, JWH-122, and JWH-250 by Rimonabant in Rhesus Monkeys

Synthetic cannabinoids have been prohibited due to abuse liability and toxicity. Four such synthetic cannabinoids, AM-2201 ([1-(5-fluoropentyl)indol-3-yl]-naphthalen-1-ylmethanone), CP-47,497 (2-[(1R,3S)-3-hydroxycyclohexyl]-5-(2-methyloctan-2-yl)phenol), JWH-122 [(4-methylnaphthalen-1-yl)-(1-pentylindol-3-yl)methanone], and JWH-250 [2-(2-methoxyphenyl)-1-(1-pentylindol-3-yl)ethanone], were tested for their capacity to produce CB1 receptor-mediated discriminative stimulus effects in two groups of rhesus monkeys. One group (n = 4) discriminated Δ9-tetrahydrocannabinol (∆9-THC; 0.1 mg/kg i.v.), and a second group (n = 4) discriminated the cannabinoid antagonist rimonabant (1 mg/kg i.v.) while receiving 1 mg/kg/12 hours of ∆9-THC. AM-2201, JWH-122, CP-47,497, JWH-250, and ∆9-THC increased ∆9-THC lever responding. Duration of action was 1-2 hours for AM-2201, JWH-122, and JWH-250 and 4-5 hours for CP-47,497 and ∆9-THC. Rimonabant (1 mg/kg) surmountably antagonized the discriminative stimulus effects of all cannabinoid agonists; the magnitude of rightward shift was 10.6-fold for AM-2201, 10.7-fold for JWH-122, 11.0-fold for CP-47,497, and 15.7-fold for JWH-250. The respective pKB values were not significantly different: 6.61, 6.65, 6.66, and 6.83. In ∆9-THC-treated monkeys discriminating rimonabant, AM-2201 (0.1 and 0.32 mg/kg), JWH-122 (0.32 and 1 mg/kg), JWH-250 (1 and 3.2 mg/kg), and CP-47,497 (0.32, 1, and 3.2 mg/kg) produced not only rate-decreasing effects that were reversed by rimonabant, but also dose-dependent, rightward shifts in the rimonabant discrimination dose-effect function. These results show striking similarity in the CB1 receptor mechanism mediating the subjective effects of AM-2201, JWH-122, JWH-250, and CP-47,497. For products containing AM-2201 and JWH-122, a short duration of action could lead to more frequent use; moreover, inattention to differences in potency among synthetic cannabinoids could underlie unexpected toxicity. Rapid reversal of effects by intravenous rimonabant has potential value in emergency situations.

Apparent CB1 Receptor Rimonabant Affinity Estimates: Combination with THC and Synthetic Cannabinoids in the Mouse In Vivo Triad Model

Synthetic cannabinoids (SCs) represent an emerging class of abused drugs associated with psychiatric complications and other substantial health risks. These ligands are largely sold over the internet for human consumption, presumably because of their high cannabinoid 1 receptor (CB1R) affinity and their potency in eliciting pharmacological effects similar to Δ9-tetrahydrocannabinol (THC), as well as circumventing laws illegalizing this plant. Factors potentially contributing to the increased prevalence of SC abuse and related hospitalizations, such as increased CB1R efficacy and non-CB1R targets, highlight the need for quantitative pharmacological analyses to determine receptor mediation of the pharmacological effects of cannabinoids. Accordingly, the present study used pA2 and pKB analyses for quantitative determination of CB1R mediation in which we utilized the CB1R-selective inverse agonist/antagonist rimonabant to elicit rightward shifts in the dose-response curves of five SCs (i.e., A-834,735D; WIN55,212-2; CP55,950; JWH-073; and CP47,497) and THC in producing common cannabimimetic effects (i.e., catalepsy, antinociception, and hypothermia). The results revealed overall similarity of pA2 and pKB values for these compounds and suggest that CB1Rs, and not other pharmacological targets, largely mediated the central pharmacological effects of SCs. More generally, affinity estimation offers a powerful pharmacological approach to assess potential receptor heterogeneity subserving in vivo pharmacological effects of SCs.

Behavioral Determinants of Cannabinoid Self-Administration in Old World Monkeys

Reinforcing effects of Δ⁹-tetrahydrocannabinol (THC), the primary active ingredient in marijuana, as assessed with self-administration (SA), has only been established in New World primates (squirrel monkeys). The objective of this study was to investigate some experimental factors that may enhance intravenous SA of THC and the cannabinoid receptor (CBR) agonist CP 55 940 in Old World monkeys (rhesus and cynomolgus), a species that has been used extensively in biomedical research. In one experiment, male rhesus monkeys (N=9) were trained to respond under a fixed-ratio 10 schedule of food presentation. The effects of CP 55 940 (1.0-10 μg/kg, i.v.) and THC (3.0-300 μg/kg, i.v.) on food-maintained responding and body temperature were determined in these subjects prior to giving them access to self-administer each drug. Both drugs dose-dependently decreased food-maintained responding. CP 55 940 (0.001-3.0 μg/kg) functioned as a reinforcer in three monkeys, whereas THC (0.01-10 μg/kg) did not have reinforcing effects in any subject. CP 55 940 was least potent to decrease food-maintained responding in the monkeys in which CP 55 940 functioned as a reinforcer. Next, THC was administered daily to monkeys until tolerance developed to rate-decreasing effects. When THC SA was reexamined, it functioned as a reinforcer in three monkeys. In a group of cocaine-experienced male cynomolgus monkeys (N=4), THC SA was examined under a second-order schedule of reinforcement; THC functioned as reinforcer in two monkeys. These data suggest that SA of CBR agonists may be relatively independent of their rate-decreasing effects in Old World monkeys. Understanding individual differences in vulnerability to THC SA may lead to novel treatment strategies for marijuana abuse.

Synthetic Pot: Not Your Grandfather's Marijuana

In the early 2000s in Europe and shortly thereafter in the USA, it was reported that 'legal' forms of marijuana were being sold under the name K2 and/or Spice. Active ingredients in K2/Spice products were determined to be synthetic cannabinoids (SCBs), producing psychotropic actions via CB1 cannabinoid receptors, similar to those of Δ9-tetrahydrocannabinol (Δ9-THC), the primary active constituent in marijuana. Often abused by adolescents and military personnel to elude detection in drug tests due to their lack of structural similarity to Δ9-THC, SCBs are falsely marketed as safe marijuana substitutes. Instead, SCBs are a highly structural diverse group of compounds, easily synthesized, which produce very dangerous adverse effects occurring by, as of yet, unknown mechanisms. Therefore, available evidence indicates that K2/Spice products are clearly not safe marijuana alternatives.

Tripping with Synthetic Cannabinoids ("Spice"): Anecdotal and Experimental Observations in Animals and Man

The phenomenon of consuming synthetic cannabinoids ("Spice") for recreational purposes is a fairly recent trend. However, consumption of cannabis dates back millennia, with numerous accounts written on the experience of its consumption, and thousands of scientific reports published on the effects of its constituents in laboratory animals and humans. Here, we focus on consolidating the scientific literature on the effects of "Spice" compounds in various behavioral assays, including assessing abuse liability, tolerance, dependence, withdrawal, and potential toxicity. In most cases, the behavioral effects of "Spice" compounds are compared with those of Δ9-tetrahydrocannabinol. Methodological aspects, such as modes of administration and other logistical issues, are also discussed. As the original "Spice" molecules never were intended for human consumption, scientifically based information about potential toxicity and short- and long-term behavioral effects are very limited. Consequently, preclinical behavioral studies with "Spice" compounds are still in a nascent stage. Research is needed to address the addiction potential and other effects, including propensity for producing tissue/organ toxicity, of these synthetic cannabimimetic "Spice" compounds.

Synthetic Cathinone and Cannabinoid Designer Drugs Pose a Major Risk for Public Health

As part of an increasing worldwide use of designer drugs, recent use of compounds containing cathinones and synthetic cannabinoids is especially prevalent. Here, we reviewed current literature on the prevalence, epidemiology, bio-behavioral effects, and detection of these compounds. Gender differences and clinical effects will also be examined. Chronic use of synthetic cathinone compounds can have major effects on the central nervous system and can induce acute psychosis, hypomania, paranoid ideation, and delusions, similar to the effects of other better-known amphetamine-type stimulants. Synthetic cannabinoid products have effects that are somewhat similar to those of natural cannabis but more potent and long-lasting than THC. Some of these compounds are potent and dangerous, having been linked to psychosis, mania, and suicidal ideation. Novel compounds are developed rapidly and new screening techniques are needed to detect them as well as a rigorous regulation and legislation reinforcement to prevent their distribution and use. Given the rapid increase in the use of synthetic cathinones and cannabinoid designer drugs, their potential for dependence and abuse, and harmful medical and psychiatric effects, there is a need for research and education in the areas of prevention and treatment.

[INCREMENT]9-Tetrahydrocannabinol discriminative stimulus effects of AM2201 and related aminoalkylindole analogs in rats

The recent recreational use of synthetic cannabinoid ligands, collectively referred to as 'Spice', has raised concerns about their safety and possible differences in their biological effect(s) from marijuana/Δ-tetrahydrocannabinol (THC). AM2201, a highly efficacious, potent cannabinoid receptor 1 (CB1R) agonist, is a recently detected compound in 'Spice' preparations. Furthermore, structural analogs of AM2201 are now being found in 'Spice'. The present studies were conducted to investigate their Δ-THC-like effects using drug (Δ-THC) discrimination in rats. Results show that the tested compounds were potent cannabinergics that generalized to the response to Δ-THC, with AM2201 being most potent, exhibiting a 14-fold potency difference over Δ-THC. The other analogs were between 2.5-fold and 4-fold more potent than THC. Surmountable antagonism of AM2201 with the selective CB1R antagonist/inverse agonist rimonabant also established that the discrimination is CB1R dependent. Time-course data reveal that AM2201 likely peaks rapidly with an in-vivo functional half-life of only 60 min. The present data confirm and extend previous observations regarding Δ-THC-like effects of 'Spice' components.

Enhanced discriminative stimulus effects of Δ(9)-THC in the presence of cannabidiol and 8-OH-DPAT in rhesus monkeys

BACKGROUND

Cannabidiol, a therapeutic with potential serotonin (5-hydroxytryptamine; 5-HT) 5-HT1A receptor agonist activity, is the second most prevalent cannabinoid in Cannabis after Δ(9)-THC. The extent to which cannabidiol modifies the effects of Δ(9)-THC has not been firmly established, especially with respect to abuse-related effects in rhesus monkeys where previously antagonistic interactions have been reported for some behavioral outcomes.

METHODS

Cannabidiol and the 5-HT1A receptor agonist (±)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT) were tested in two separate discrimination assays in rhesus monkeys. One group (n=6) discriminated Δ(9)-tetrahydrocannabinol (Δ(9)-THC; 0.1mg/kg i.v.); a second group (n=6) discriminated the cannabinoid antagonist rimonabant (1mg/kg i.v.) while receiving Δ(9)-THC daily (1mg/kg/12hs.c.). Responding was maintained under a fixed ratio 5 schedule of stimulus-shock termination.

RESULTS

Both training drugs dose-dependently increased the percentage of responses on the respective drug-associated levers. Cannabidiol (up to 17.8mg/kg) and 8-OH-DPAT (up to 0.178mg/kg) did not substitute for either training drug; however, both significantly increased the potency of Δ(9)-THC to produce discriminative stimulus effects. Moreover, 8-OH-DPAT significantly attenuated the discriminative stimulus effects of rimonabant, whereas cannabidiol did not modify the rimonabant discriminative stimulus.

CONCLUSIONS

These results, which are consistent with cannabidiol lacking CB1 receptor agonist or antagonist activity in vivo, demonstrate enhancement of the effects of Δ(9)-THC by cannabidiol, albeit at cannabidiol amounts larger than those in Cannabis or cannabidiol-based therapeutics (nabiximols). In addition to showing that cannabidiol and a 5-HT1A receptor agonist have overlapping behavioral effects, the current results suggest that 5-HT1A agonism enhances the CB1 receptor-mediated effects of Δ(9)-THC.

A high efficacy cannabinergic ligand (AM4054) used as a discriminative stimulus: Generalization to other adamantyl analogs and Δ(9)-THC in rats

In addition to endogenous lipids, the two main cloned receptors (CB1R and CB2R) of the endocannabinoid signaling system (ECS) can be activated (and blocked) by various exogenous ligands. A relatively novel template for CB1R activators contains an adamantyl moiety as a key structural subunit, the first being the cannabinergic AM411. Additional chemical optimization efforts using the classical tricyclic scaffold led to AM4054. Here we explored the in vivo consequences of novel adamantyl analogs in rats trained to recognize the effects of the potent adamantyl cannabinergic AM4054. Rats were trained to discriminate between AM4054 (0.1mg/kg) and vehicle. Three AM4054 analogs and Δ(9)-THC were tested for generalization (substitution) and antagonism was assessed with rimonabant. We found that all cannabinergics resulted in response generalization to the target stimulus AM4054. The order of potency was: AM4054≥AM4083≥AM4050>AM4089>Δ(9)-THC. The CB1R antagonist/inverse agonist rimonabant blocked the discriminative stimulus effects of AM4054. Thus the examined structural modifications affected binding affinities but did not markedly change potencies with the exception of AM4089. In vitro (cAMP assay) functional data have suggested that AM4089 behaves as a partial rather than as a full agonist at CB1R which could explain its lower potency compared to AM4054 (Thakur et al., 2013). The 9β-formyl functionality at C-9 position was identified as an important pharmacophore yielding high in vivo potency. Antagonism by rimonabant suggested CB1R mediation.

Adverse Effects of Synthetic Cannabinoids: Management of Acute Toxicity and Withdrawal

Although several chemical structural classes of synthetic cannabinoids (SCs) were recently classified as Schedule I substances, rates of use and cases of serious toxic effects remain high. While case reports and media bring attention to severe SC toxicity, daily SC use resulting in dependence and withdrawal is a significant concern that is often overlooked when discussing the risks of these drugs. There is a rich literature on evidence-based approaches to treating substance use disorders associated with most abused drugs, yet little has been published regarding how to best treat symptoms related to SC dependence given its recency as an emerging clinically significant issue. This review provides a background of the pharmacology of SCs, recent findings of adverse effects associated with both acute intoxication and withdrawal as a consequence of daily use, and treatment approaches that have been implemented to address these issues, with an emphasis on pharmacotherapies for managing detoxification. In order to determine prevalence of use in cannabis smokers, a population at high risk for SC use, we obtained data on demographics of SC users, frequency of use, and adverse effects over a 3.5-year period (2012-2015) in the New York City metropolitan area, a region with a recent history of high SC use. While controlled studies on the physiological and behavioral effects of SCs are lacking, it is clear that risks associated with using these drugs pertain not only to the unpredictable and severe nature of acute intoxication but also to the effects of long-term, chronic use. Recent reports in the literature parallel findings from our survey, indicating that there is a subset of people who use SCs daily. Although withdrawal has not been systematically characterized and effective treatments have yet to be elucidated, some symptom relief has been reported with benzodiazepines and the atypical antipsychotic, quetiapine. Given the continued use and abuse of SCs, empirical studies characterizing (1) SCs acute effects, (2) withdrawal upon cessation of use, and (3) effective treatment strategies for SC use disorder are urgently needed.

Synthetic Cannabinoids-Further Evidence Supporting the Relationship Between Cannabinoids and Psychosis

Consumption of synthetic mind-altering compounds, also known as "new psychoactive substances," is increasing globally at an alarming rate. Synthetic cannabinoids (SCs) are among the most commonly used new psychoactive substances. They are usually purchased as marijuana-like drugs, marketed as herbal blends and perceived as risk-free by inexperienced users. Yet, contrary to Δ(9)-tetrahydrocannabinol, SCs may lead to severe health consequences, including anxiety, tachycardia, hallucinations, violent behavior, and psychosis. This review focuses on the latest (2010-2015) evidence of psychotic symptoms induced by ingestion of products containing SCs. Reports suggesting that SCs may either exacerbate previously stable psychotic symptoms (in vulnerable individuals) or trigger new-onset psychosis (in individuals with no previous history of psychosis) are reviewed. Pharmacology and toxicology of these compounds are discussed, with particular reference to their psychoactive effects.

Fatal intoxication with synthetic cannabinoid MDMB-CHMICA

MDMB-CHMICA is a synthetic cannabinoid that appeared on the European drug market in September 2014. This substance was found in Poland in the herbal mixture "Mocarz" ("Strongman"), which caused a large outbreak of intoxications at the beginning of July 2015. This paper describes the circumstances of death and toxicological findings in a fatal intoxication with MDMB-CHMICA (in combination with alcohol). Loss of consciousness and asystole occurred a few minutes after smoking the 'legal high'. The man died after 4 days of hospitalisation. The cause of death accepted by the medical examiner was multiple organ failure. MDMB-CHMICA was detected and quantified in blood (ante- and postmortem) and internal organs tissues. The samples were analysed using liquid chromatography with mass spectrometry (LC-MS/MS). The concentration of MDMB-CHMICA in antemortem blood was 5.6 ng/mL. Although the death occurred after 4 days from administration a relatively high concentration (2.6 ng/g) was estimated in the brain. Traces of this compound were also found in other postmortem materials (blood, stomach, liver, bile, and kidney). The presented case shows the health risks associated with MDMB-CHMICA use. The administration of this substance can lead to the number of organ failures, cardiac arrest and consequently death.

Cross-tolerance to cannabinoids in morphine-tolerant rhesus monkeys

RATIONALE

Opioids remain the drugs of choice for treating moderate to severe pain, although adverse effects limit their use. Therapeutic utility might be improved by combining opioids with other drugs to enhance analgesic effects, but only if adverse effects are not similarly changed.

OBJECTIVE

Cannabinoids have been shown to enhance the antinociceptive potency of opioids without increasing other effects; this study examined whether the effectiveness of cannabinoids is altered in morphine-dependent monkeys.

METHODS

Four monkeys received up to 10 mg/kg morphine twice daily. Changes in the antinociceptive effects of opioid receptor agonists (morphine, U50,488) and cannabinoid receptor agonists (WIN 55,212, CP 55,940, and Δ(9)-tetrahydrocannabinol [THC]) were determined by measuring the latency for monkeys to remove their tails from 40, 50, 54, and 58 °C water.

RESULTS

Before treatment, all drugs increased tail withdrawal latency from warm (54 °C) water. Chronic morphine treatment decreased the potency of each drug; the magnitude of rightward shift in dose-effect curves was greatest for morphine, WIN 55,212 and CP 55,940 with at least sixfold shifts for each drug during treatment. Discontinuation of morphine treatment resulted in signs that are indicative of withdrawal, including increased heart rate, decreased daytime activity, and tongue movement.

CONCLUSION

Tolerance developed to the antinociceptive effects of morphine and cross-tolerance developed to cannabinoids under conditions that produced modest physical dependence. Compared with the doses examined in this study, much smaller doses of opioids have antinociceptive effects when given with cannabinoids; it is possible that tolerance will not develop to chronic treatment with opioid/cannabinoid mixtures.

Δ9-Tetrahydrocannabinol-like discriminative stimulus effects of compounds commonly found in K2/Spice

A number of cannabinoid compounds are being sold in the form of incense as 'legal' alternatives to marijuana. The purpose of these experiments was to determine whether the most common of these compounds have discriminative stimulus effects similar to Δ-tetrahydrocannabinol (Δ-THC), the main active component in marijuana. Locomotor depressant effects of JWH-018, JWH-073, JWH-200, JWH-203, JWH-250, AM-2201, and CP 47,497-C8-homolog were tested in mice. The compounds were then tested for substitution in rats trained to discriminate Δ-THC (3 mg/kg, intraperitoneally). The time course of the peak dose of each compound was also tested. Each of the synthetic cannabinoids dose-dependently decreased locomotor activity for 1-2 h. Each of the compounds fully substituted for the discriminative stimulus effects of Δ-THC, mostly at doses that produced only marginal amounts of rate suppression. JWH-250 and CP 47,497-C8-homolog suppressed response rates at doses that fully substituted for Δ-THC. The time courses varied markedly between compounds. Most of the compounds had a shorter onset than Δ-THC, and the effects of three of the compounds lasted substantially longer (JWH-073, JWH-250, and CP 47,497-C8-homolog). Several of the most commonly used synthetic cannabinoids produce behavioral effects comparable with those of Δ-THC, which suggests that these compounds may share the psychoactive effects of marijuana responsible for abuse liability. The extremely long time course of the discriminative stimulus effects and adverse effects of CP 47,497-C8-homolog suggest that CP 47,497-C8-homolog may be associated with increased hazards among humans.