Next generation of novel psychoactive substances on the horizon - A complex problem to face

Heterodimeric D1-D2 dopamine receptors: a review

This review summarizes modern data on the structure and functions ofheteromersformed by D1 and D2 dopamine receptors focusing on their role in the mechanisms of drug dependence. This article discusses potential functional significance of heterodimeric D1-D2 dopamine receptorsdue to their localization in the brain as well as unique pharmacological propertiesversus constituent monomers. It is shown that heteromerization results in dramatic changes in activated signaling pathways compare to the corresponding monomers. These studies update our current knowledge of ligand-receptor interactions and provide better understanding of dopamine receptors pharmacology. Furthermore elucidation of significance of heterodimeric D1-D2 dopamine receptors as drug targets is important for the development of new effective drug addiction treatment.

Neuropharmacology of 3,4-Methylenedioxypyrovalerone (MDPV), Its Metabolites, and Related Analogs

3,4-Methylenedioxypyrovalerone (MDPV) is a psychoactive component of so-called bath salts products that has caused serious medical consequences in humans. In this chapter, we review the neuropharmacology of MDPV and related analogs, and supplement the discussion with new results from our preclinical experiments. MDPV acts as a potent uptake inhibitor at plasma membrane transporters for dopamine (DAT) and norepinephrine (NET) in nervous tissue. The MDPV formulation in bath salts is a racemic mixture, and the S isomer is much more potent than the R isomer at blocking DAT and producing abuse-related effects. Elevations in brain extracellular dopamine produced by MDPV are likely to underlie its locomotor stimulant and addictive properties. MDPV displays rapid pharmacokinetics when injected into rats (0.5-2.0 mg/kg), with peak plasma concentrations achieved by 10-20 min and declining quickly thereafter. MDPV is metabolized to 3,4-dihydroxypyrovalerone (3,4-catechol-PV) and 4-hydroxy-3-methoxypyrovalerone (4-OH-3-MeO-PV) in vivo, but motor activation produced by the drug is positively correlated with plasma concentrations of parent drug and not its metabolites. 3,4-Catechol-PV is a potent uptake blocker at DAT in vitro but has little activity after administration in vivo. 4-OH-3-MeO-PV is the main MDPV metabolite but is weak at DAT and NET. MDPV analogs, such as α-pyrrolidinovalerophenone (α-PVP), display similar ability to inhibit DAT and increase extracellular dopamine concentrations. Taken together, these findings demonstrate that MDPV and its analogs represent a unique class of transporter inhibitors with a high propensity for abuse and addiction.

New psychoactive substances (NPS) on cryptomarket fora: An exploratory study of characteristics of forum activity between NPS buyers and vendors

BACKGROUND

The continual diversification of new psychoactive substances (NPS) circumventing legislation creates a public health and law enforcement challenge, and one particularly challenged by availability on Hidden Web cryptomarkets.

METHODS

This is the first study of its kind which aimed to explore and characterise cryptomarket forum members' views and perspectives on NPS vendors and products within the context of Hidden Web community dynamics. An internal site search was conducted on two cryptomarkets popular with NPS vendors and hosting fora; Alphabay and Valhalla, using the search terms of 40 popular NPS in the seven categories of stimulant/cathinone; GABA activating; hallucinogen, dissociative, cannabinoid, opioid and other/unspecified/uncategorised NPS. 852 identified threads relating to the discussion of these NPS were generated. Following exclusion of duplicates, 138 threads remained. The Empirical Phenomenological Psychological method of data analysis was applied. Four themes and 32 categories emerged.

RESULTS

120 vendors selling NPS were visible on Alphabay, and 21 on Valhalla. Themes were 'NPS Cryptomarkets and Crypto-community interest in NPS'; 'Motives for NPS use'; 'Indigenous Crypto Community Harm Reduction'; and 'Cryptomarket Characteristics underpinning NPS trafficking', with two higher levels of abstraction centring on 'NPS vendor reputation' and 'NPS transactioning for personal use'. NPS cryptomarket characteristics centred on generation of trust, honesty and excellent service. Users appeared well informed, with harm reduction and vendor information exchange central to NPS market dynamics. GABA activating substances appeared most popular in terms of buyer interest on cryptomarkets. Interest in sourcing 'old favorite' stimulant and dissociative NPS was evident, alongside the sequential and concurrent poly use of NPS, and use of NPS with illicit drugs such as MDMA.

CONCLUSION

Continued monitoring of new trends in NPS within Surface Web and cryptomarkets are warranted. A particular focus on the rising market in prescribed benzodiazepine and Z-hypnotic drugs should be included.

New psychoactive substances: an overview on recent publications on their toxicodynamics and toxicokinetics

This review article covers English-written and PubMed-listed review articles and original studies published between January 2015 and April 2016 dealing with the toxicodynamics and toxicokinetics of new psychoactive substances. Compounds covered include stimulants and entactogens, synthetic cannabinoids, tryptamines, NBOMes, phencyclidine-like drugs, benzodiazepines, and opioids. First, an overview and discussion is provided on timely review articles followed by an overview and discussion on recent original studies. Both sections are then concluded by an opinion on these latest developments. This review shows that the NPS market is still highly dynamic and that the data published on their toxicodynamics and toxicokinetics can hardly keep pace with the appearance of new entities. However, data available are very helpful to understand and predict how NPS may behave in severe intoxication. The currently best-documented parameter is the in vitro metabolism of NPS, a prerequisite to allow detection of NPS in biological matrices in cases of acute intoxications or chronic consumption. However, additional data such as their chronic toxicity are still lacking.

Pharmacology of Valinate and tert-Leucinate Synthetic Cannabinoids 5F-AMBICA, 5F-AMB, 5F-ADB, AMB-FUBINACA, MDMB-FUBINACA, MDMB-CHMICA, and Their Analogues

Indole and indazole synthetic cannabinoids (SCs) featuring l-valinate or l-tert-leucinate pendant group have recently emerged as prevalent recreational drugs, and their use has been associated with serious adverse health effects. Due to the limited pharmacological data available for these compounds, 5F-AMBICA, 5F-AMB, 5F-ADB, AMB-FUBINACA, MDMB-FUBINACA, MDMB-CHMICA, and their analogues were synthesized and assessed for cannabimimetic activity in vitro and in vivo. All SCs acted as potent, highly efficacious agonists at CB1 (EC50 = 0.45-36 nM) and CB2 (EC50 = 4.6-128 nM) receptors in a fluorometric assay of membrane potential, with a general preference for CB1 activation. The cannabimimetic properties of two prevalent compounds with confirmed toxicity in humans, 5F-AMB and MDMB-FUBINACA, were demonstrated in vivo using biotelemetry in rats. Bradycardia and hypothermia were induced by 5F-AMB and MDMB-FUBINACA doses of 0.1-1 mg/kg (and 3 mg/kg for 5F-AMB), with MDMB-FUBINACA showing the most dramatic hypothermic response recorded in our laboratory for any SC (>3 °C at 0.3 mg/kg). Reversal of hypothermia by pretreatment with a CB1, but not CB2, antagonist was demonstrated for 5F-AMB and MDMB-FUBINACA, consistent with CB1-mediated effects in vivo. The in vitro and in vivo data indicate that these SCs act as highly efficacious CB receptor agonists with greater potency than Δ(9)-THC and earlier generations of SCs.

Age, period, and cohort effects in synthetic cannabinoid use among US adolescents, 2011-2015

BACKGROUND

Synthetic cannabinoids use has been a public health concern given association with hospitalization and death among users. While national reports estimate that reported use is declining among adolescents, differences by birth cohort may indicate subgroups who remain at higher risk, both in the overall adolescent population and among demographic subgroups.

METHODS

We estimated age, period, and cohort models of self-reported past-year synthetic cannabinoid use (queried as "synthetic marijuana" ["K2," "Spice"]) among 54,865 adolescents aged 13-19 attending high school from 2011 to 2015.

RESULTS

Past-year use decreased from 11.86% in 2011 to 4.75% in 2015. This decrease was best represented as a linear downward trend. When stratified by key covariates, however, results indicated evidence of a positive cohort effect for students of higher socioeconomic status (SES). For those students, use did not decrease at the same rate as the overall population; younger cohorts of high SES students remain at higher risk for synthetic cannabinoid use than older cohorts as well as lower SES peers. A similar and stronger association was found for frequent marijuana users (≥20 occasions of past-year use). Multi-level models indicated that groups at highest risk included older adolescents, Hispanics and other/mixed race students, cigarette users, and frequent marijuana users.

CONCLUSION

Synthetic cannabinoid use is associated with morbidity as well as mortality; continued attention to reducing synthetic cannabinoid use remains an important public health priority to maximizing student health.

Self-reported use of novel psychoactive substances among attendees of electronic dance music venues

BACKGROUND

Novel psychoactive substances (NPSs) continue to emerge in the United States and worldwide. Few epidemiological studies have examined the prevalence and correlates of use.

OBJECTIVE

We examined the extent of NPS use in a high-risk population-attendees of electronic dance music (EDM) parties at nightclubs and festivals.

METHODS

We surveyed 682 adults (age 18-25) entering EDM events at nightclubs and festivals in New York City (NYC) in 2015. A variation of time-space sampling was used. We examined the prevalence of self-reported use of 196 NPS and correlates of any NPS use.

RESULTS

Over a third (35.1%) of participants reported lifetime use of any NPS. Self-reported use of synthetic cannabinoids was most prevalent (16.3%), followed by psychedelic phenethylamines (14.7%; 2C series: 10.3%, 2-(4-iodo-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine [NBOMe] series: 9.0%, Dox series: 3.5%), synthetic cathinones ("bath salts", 6.9%), other psychedelics (6.6%), tryptamines (5.1%), and dissociatives (4.3%). 2C-I was the most prevalent 2C series drug (5.1%); methylone was the most prevalent synthetic cathinone (3.3%), 2-MeO-ketamine was the most prevalent dissociative (3.7%), and 1P-lysergic acid diethylamide (LSD) (2.9%) was the most prevalent non-phenethylamine psychedelic. Risk factors for NPS use included Ecstasy/MDMA/Molly, LSD, and ketamine use; identifying as bisexual (compared to heterosexual), reporting higher frequency of nightclub/festival attendance, and being surveyed outside of a festival (compared to those surveyed outside of nightclubs).

DISCUSSION

NPS use is prevalent in the nightclub and festival scenes in NYC. Since individuals in these scenes-especially frequent attendees-are at high risk for use, prevention and harm reduction services need to be geared toward this population.

Cytotoxic Activity of Pyrovalerone Derivatives, an Emerging Group of Psychostimulant Designer Cathinones

The growing popularity of novel psychoactive substances (NPS) has aroused the concerns of public health specialists. The pyrovalerone derivatives are a branch of synthetic cathinones, a very popular group of psychostimulant NPS. Despite numerous case reports of fatal intoxications, little is known about the cytotoxicity of these substances. Therefore, this study was aimed to evaluate the toxic properties of pyrovalerone, its highly prevalent derivative 3,4-methylenedioxypyrovalerone (3,4-MDPV) with its two major metabolites (catechol-MDPV and methylcatechol-MDPV) and the structural isomer 2,3-MDPV, together with newer members of the group, i.e., α-pyrrolidinovalerothiophenone (α-PVT) and α-pyrrolidinooctanophenone (PV9), using model human cell lines for neurons (SH-SY5Y), hepatocytes (Hep G2), and upper airway epithelium (RPMI 2650). We found that the first generation pyrovalerones (pyrovalerone, 3,4-MDPV, and 2,3-MDPV) produced a modest decrease of mitochondrial activity in the three examined cell lines, but were active in lower concentrations than methamphetamine used as a reference psychostimulant compound. Since catechol-MDPV displayed greater toxic potential than the parent compound, we suggest that the toxicity of 3,4-MDPV could be attributed to activity of this metabolite. Strikingly, the two new generation pyrovalerones, α-PVT and PV9, seem to be the most potent cytotoxic compounds: both induced highly pronounced mitochondrial dysfunction; the latter also demonstrated significant damage to cell membranes. The reported in vitro toxic activity of pyrovalerone cathinones against different cell types reinforces existing concerns regarding the health risks associated with the intake of these drugs.

The 2-alkyl-2H-indazole regioisomers of synthetic cannabinoids AB-CHMINACA, AB-FUBINACA, AB-PINACA, and 5F-AB-PINACA are possible manufacturing impurities with cannabimimetic activities

Indazole-derived synthetic cannabinoids (SCs) featuring an alkyl substituent at the 1-position and l-valinamide at the 3-carboxamide position (e.g., AB-CHMINACA) have been identified by forensic chemists around the world, and are associated with serious adverse health effects. Regioisomerism is possible for indazole SCs, with the 2-alkyl-2H-indazole regioisomer of AB-CHMINACA recently identified in SC products in Japan. It is unknown whether this regiosiomer represents a manufacturing impurity arising as a synthetic byproduct, or was intentionally synthesized as a cannabimimetic agent. This study reports the synthesis, analytical characterization, and pharmacological evaluation of commonly encountered indazole SCs AB-CHMINACA, AB-FUBINACA, AB-PINACA, 5F-AB-PINACA and their corresponding 2-alkyl-2H-indazole regioisomers. Both regioisomers of each SC were prepared from a common precursor, and the physical properties, ¹H and ¹³C nuclear magnetic resonance spectroscopy, gas chromatography-mass spectrometry, and ultraviolet-visible spectroscopy of all SC compounds are described. Additionally, AB-CHMINACA, AB-FUBINACA, AB-PINACA, and 5F-AB-PINACA were found to act as high potency agonists at CB₁ (EC₅₀ = 2.1-11.6 nM) and CB₂ (EC₅₀ = 5.6-21.1 nM) receptors in fluorometric assays, while the corresponding 2-alkyl-2H-indazole regioisomers demonstrated low potency (micromolar) agonist activities at both receptors. Taken together, these data suggest that 2-alkyl-2H-indazole regioisomers of AB-CHMINACA, AB-FUBINACA, AB-PINACA, and 5F-AB-PINACA are likely to be encountered by forensic chemists and toxicologists as the result of improper purification during the clandestine synthesis of 1-alkyl-1H-indazole regioisomers, and can be distinguished by differences in gas chromatography-mass spectrometry fragmentation pattern.

Detection of "bath salts" and other novel psychoactive substances in hair samples of ecstasy/MDMA/"Molly" users

BACKGROUND

Ecstasy (MDMA) in the US is commonly adulterated with other drugs, but research has not focused on purity of ecstasy since the phenomenon of "Molly" (ecstasy marketed as pure MDMA) arose in the US.

METHODS

We piloted a rapid electronic survey in 2015 to assess use of novel psychoactive substances (NPS) and other drugs among 679 nightclub/festival-attending young adults (age 18-25) in New York City. A quarter (26.1%) of the sample provided a hair sample to be analyzed for the presence of select synthetic cathinones ("bath salts") and some other NPS. Samples were analyzed using fully validated UHPLC-MS/MS methods. To examine consistency of self-report, analyses focused on the 48 participants with an analyzable hair sample who reported lifetime ecstasy/MDMA/Molly use.

RESULTS

Half (50.0%) of the hair samples contained MDMA, 47.9% contained butylone, and 10.4% contained methylone. Of those who reported no lifetime use of "bath salts", stimulant NPS, or unknown pills or powders, about four out of ten (41.2%) tested positive for butylone, methylone, alpha-PVP, 5/6-APB, or 4-FA. Racial minorities were more likely to test positive for butylone or test positive for NPS after reporting no lifetime use. Frequent nightclub/festival attendance was the strongest predictor of testing positive for MDMA, butylone, or methylone.

DISCUSSION

Results suggest that many ecstasy-using nightclub/festival attendees may be unintentionally using "bath salts" or other NPS. Prevention and harm reduction education is needed for this population and "drug checking" (e.g., pill testing) may be beneficial for those rejecting abstinence.