Abuse of New Psychoactive Substances: Threats and Solutions

Evaluating cross-reactivity of new psychoactive substances (NPS) in human whole blood by enzyme-linked immunosorbent assay (ELISA)

Due to the increase in the use of novel psychoactive substances (NPS) and their overall prevalence, it is important to have effective and reliable screening technologies to detect NPS in biological matrices. Enzyme-linked immunosorbent assays (ELISA) are among the most popular screening methods. To evaluate the effectiveness of ELISA for NPS detection, five subclasses of NPS (novel synthetic opioids, fentanyl analogs, stimulants, benzodiazepines and hallucinogens) were evaluated in whole blood for their cross-reactivity on commercially available ELISA kits. A variety of novel synthetic opioids were tested at concentrations of 1-80 ng/mL and 50-2000 ng/mL and demonstrated no cross-reactivity to a morphine ELISA plate at either concentration range. Fentanyl analogs were tested at concentrations ranging from 0.01 to 1 ng/mL and had cross-reactivities ranging from 8% to 178% on the fentanyl ELISA kit used. Both para-chloro fentanyl (178%) and acryl fentanyl (164%) showed cross-reactivities well above that of fentanyl. Novel stimulants were tested at concentrations of 0.5-40 ng/mL and 20-2,000 ng/mL. 4-Fluoroamphetamine was the only novel stimulant with cross-reactivity (3,354%) to the amphetamine ELISA plate. Novel benzodiazepines were tested at concentrations of 1-40 ng/mL on a benzodiazepine plate. Cross-reactivities ranged from 36.1% to 263%, with desalkylflurazepam having the highest cross-reactivity. Finally, novel hallucinogens were tested at concentrations of 0.5-10 ng/mL on a phencyclidine (PCP) ELISA plate, which produced no cross-reactivity and then with 10-1,000 ng/mL, which gave results from 56.6% to 151%. Both hydroxy-PCP (151%) and chloro-PCP (137%) showed cross-reactivities above that of PCP. This research has demonstrated the utility of using ELISA-based screening for novel benzodiazepines, hallucinogens and for fentanyl analogs; however, there is limited application and risk of false-negative results for the other drug classes due to low or non-existent cross-reactivities.

Deep Learning-Enabled MS/MS Spectrum Prediction Facilitates Automated Identification Of Novel Psychoactive Substances

The market for illicit drugs has been reshaped by the emergence of more than 1100 new psychoactive substances (NPS) over the past decade, posing a major challenge to the forensic and toxicological laboratories tasked with detecting and identifying them. Tandem mass spectrometry (MS/MS) is the primary method used to screen for NPS within seized materials or biological samples. The most contemporary workflows necessitate labor-intensive and expensive MS/MS reference standards, which may not be available for recently emerged NPS on the illicit market. Here, we present NPS-MS, a deep learning method capable of accurately predicting the MS/MS spectra of known and hypothesized NPS from their chemical structures alone. NPS-MS is trained by transfer learning from a generic MS/MS prediction model on a large data set of MS/MS spectra. We show that this approach enables a more accurate identification of NPS from experimentally acquired MS/MS spectra than any existing method. We demonstrate the application of NPS-MS to identify a novel derivative of phencyclidine (PCP) within an unknown powder seized in Denmark without the use of any reference standards. We anticipate that NPS-MS will allow forensic laboratories to identify more rapidly both known and newly emerging NPS. NPS-MS is available as a web server at https://nps-ms.ca/, which provides MS/MS spectra prediction capabilities for given NPS compounds. Additionally, it offers MS/MS spectra identification against a vast database comprising approximately 8.7 million predicted NPS compounds from DarkNPS and 24.5 million predicted ESI-QToF-MS/MS spectra for these compounds.

Identification of Emerging Novel Psychoactive Substances by Retrospective Analysis of Population-Scale Mass Spectrometry Data Sets

Over the last two decades, hundreds of new psychoactive substances (NPSs), also known as "designer drugs", have emerged on the illicit drug market. The toxic and potentially fatal effects of these compounds oblige laboratories around the world to screen for NPS in seized materials and biological samples, commonly using high-resolution mass spectrometry. However, unambiguous identification of a NPS by mass spectrometry requires comparison to data from analytical reference materials, acquired on the same instrument. The sheer number of NPSs that are available on the illicit market, and the pace at which new compounds are introduced, means that forensic laboratories must make difficult decisions about which reference materials to acquire. Here, we asked whether retrospective suspect screening of population-scale mass spectrometry data could provide a data-driven platform to prioritize emerging NPSs for assay development. We curated a suspect database of precursor and diagnostic fragment ion masses for 83 emerging NPSs and used this database to retrospectively screen mass spectrometry data from 12,727 urine drug screens from one Canadian province. We developed integrative computational strategies to prioritize the most reliable identifications and tracked the frequency of these identifications over a 3 year study period between August 2019 and August 2022. The resulting data were used to guide the acquisition of new reference materials, which were in turn used to validate a subset of the retrospective identifications. Last, we took advantage of matching clinical reports for all 12,727 samples to systematically benchmark the accuracy of our retrospective data analysis approach. Our work opens up new avenues to enable the rapid detection of emerging illicit drugs through large-scale reanalysis of mass spectrometry data.

Festivals following the easing of COVID-19 restrictions: Prevalence of new psychoactive substances and illicit drugs

The market for illicit drugs and new psychoactive substances (NPS) has grown significantly and people attending festivals have been identified as being at high risk (high extent and frequency of substance use). Traditional public health surveillance data sources have limitations (high costs, long implementation times, and ethical issues) and wastewater-based epidemiology (WBE) can cost-effectively support surveillance efforts. Influent wastewater samples were analyzed for NPS and illicit drug consumption collected during New Year period (from 29-Dec-2021 to 4-Jan-2022) and a summer Festival (from 29-June-2022 to 12-July-2022) in a large city in Spain. Samples were analyzed for phenethylamines, cathinones, opioids, benzodiazepines, plant-based NPS, dissociatives, and the illicit drugs methamphetamine, MDA, MDMA, ketamine, heroin, cocaine, and pseudoephedrine by liquid chromatography mass spectrometry. High consumption rates of specific NPS and established illicit drugs were identified at the peak of each event. Furthermore, a dynamic change in NPS use (presence and absence of substances) was detected over a period of six months. Eleven NPS, including synthetic cathinones, benzodiazepines, plant-based NPS and dissociatives, and seven illicit drugs were found across both the New Year and summer Festival. Statistically significant differences (p < 0.05) were seen for 3-MMC (New Year vs summer Festival), eutylone (New Year vs summer Festival), cocaine (summer Festival vs normal week and summer Festival vs New Year), MDMA (New Year vs normal week and summer Festival vs normal week), heroin (summer Festival vs New Year) and pseudoephedrine (summer Festival vs New Year). This WBE study assessed the prevalence of NPS and illicit drugs at festivals following the reduction of the COVID-19 pandemic restrictions highlighting the high use of specific substances at the peak of each event. This approach identified in a cost-effective and timely manner without any ethical issues the most used drugs and changes in use patterns and, thus, can complement public health information.

Methcathinone Increases Visually-evoked Neuronal Activity and Enhances Sensory Processing Efficiency in Mice

Methcathinone (MCAT) belongs to the designer drugs called synthetic cathinones, which are abused worldwide for recreational purposes. It has strong stimulant effects, including enhanced euphoria, sensation, alertness, and empathy. However, little is known about how MCAT modulates neuronal activity in vivo. Here, we evaluated the effect of MCAT on neuronal activity with a series of functional approaches. C-Fos immunostaining showed that MCAT increased the number of activated neurons by 6-fold, especially in sensory and motor cortices, striatum, and midbrain motor nuclei. In vivo single-unit recording and two-photon Ca2+ imaging revealed that a large proportion of neurons increased spiking activity upon MCAT administration. Notably, MCAT induced a strong de-correlation of population activity and increased trial-to-trial reliability, specifically during a natural movie stimulus. It improved the information-processing efficiency by enhancing the single-neuron coding capacity, suggesting a cortical network mechanism of the enhanced perception produced by psychoactive stimulants.

Advances in urinary biomarker research of synthetic cannabinoids

New psychoactive substances (NPS) are chemical compounds designed to mimic the action of existing illicit recreational drugs. Synthetic cannabinoids (SCs) are a subclass of NPS which bind to the cannabinoid receptors, CB1 and CB2, and mimic the action of cannabis. SCs have dominated recent NPS seizure reports worldwide. While urine is the most common matrix for drug-of-abuse testing, SCs undergo extensive Phase I and Phase II metabolism, resulting in almost undetectable parent compounds in urine samples. Therefore, the major urinary metabolites of SCs are usually investigated as surrogate biomarkers to identify their consumption. Since seized urine samples after consuming novel SCs may be unavailable in a timely manner, human hepatocytes, human liver microsomes and human transporter overexpressed cell lines are physiologically-relevant in vitro systems for performing metabolite identification, metabolic stability, reaction phenotyping and transporter experiments to establish the disposition of SC and its metabolites. Coupling these in vitro experiments with in vivo verification using limited authentic urine samples, such a two-pronged approach has proven to be effective in establishing urinary metabolites as biomarkers for rapidly emerging SCs.

A Review on Spike and Recovery Method in Analytical Method Development and Validation

In multidisciplinary science, Analytical approaches based on spike and recovery (SAR) play a substantial role in analytical testing. The spike and recovery method is an important technique for analyzing and accessing the accuracy of analytical methods. The goal of this review seeks to provide clarity on the role of SAR methods in the forensic science discipline. Recent literature has been searched from numerous databases like Google, Web of Sciences, Scopus, PubMed, Google Scholar, and SciFinder. Websites like Science Direct are critically explored to gather scientific reports related to SAR utility. This review discusses the applications and current role of the SAR methods in Forensic Toxicology. It is suggested as one of the major parameters in the validation of the analytical method. SAR methodology is extremely important for the identification and quantitation of analytes in the sample matrix. Moreover, the extension of SAR methods to any scientific discipline is equally important for quality assurance. All relevant processes like method development and its optimization, quality control, and assurance rely on SAR-based studies. However, the method requires better apprehension and needs to be utilized using standard guidelines.

Pattern of novel psychoactive substance use among patients presented to the poison control centre of Ain Shams University Hospitals, Egypt: A cross-sectional study

Background

Novel psychoactive substances (NPSs) are relatively new substances in the illicit drug market, not previously listed in the United Nations Office on Drugs and Crime (UNDOC). Strox and Voodoo are considered some of the most popular blends of NPS in the Egyptian drug market.

Objectives

The current study was conducted to assess NPS's use pattern: Voodoo and Strox among acutely intoxicated patients presented to the poison control center of Ain Shams University Hospitals (PCC- ASUH).

Methods

A single center based cross-sectional study was carried out in the PCC-ASUH among acutely intoxicated patients presenting to the emergency department (ED) over four months (from January–April 2019. using a previously adopted and validated Fahmy and El-Sherbini socioeconomic scale (SES). Data were presented as mean, median and range as appropriate. Both smoking and crowding indexes were calculated and presented as previously reported.

Results

Fifty-one patients were presented to the ED of PCC-ASUH during the study period. A total of 96.1% (n = 49) were males. The mean age was 25 ± 7.5 years. The most common NPS used was Strox: 54.9% (n = 28), followed by Voodoo: 27.4% (n = 14). Neurological and gastrointestinal (GI) symptoms were the most frequent presentations. The most common motive behind NPS use was the desire to give a trial of new psychoactive substances. The mean SES score was 35.1 ± 13.17. Most patients have the preparatory as the highest education 36.0% (n = 18).

Conclusions

NPS use is common among young males in preparatory education from different social classes, starting it most commonly as a means to experiencing a new high. Neurological and GI manifestations are the most common presenting symptoms of NPS intoxication.

Clinical Presentations and Predictors of In-Hospital Mortality in Illicit Drug Users in the New Psychoactive Substances (NPS) Endemic Era in Taiwan

Predictors of mortality in illicit drug users involving Novel Psychoactive Substances (NPS) and multiple substances have not been elucidated. We aimed to define predictors of mortality in the NPS endemic era’s illicit drug users to strengthen patient care in emergency treatment. This was a retrospective study. LC-MS/MS-confirmed positive illicit drug users who visited the emergency departments (ED) of six medical systems were enrolled. Demographic information, physical examinations, and laboratory data were abstracted for mortality analysis. There were 16 fatalities in 355 enrolled patients. The most frequently used illicit drugs were amphetamines, followed by opioids, cathinones, and ketamine. The most frequently detected cathinones among the 16 synthetic cathinones were eutylone, followed by mephedrone. The combined use of cathinones and ketamine was most commonly observed in our results. Univariate analysis revealed that the mortality patients were older, with deep coma, faster heart rate and respiratory rate, lower blood pressures and O2 room air saturation, more seizures, abnormal breath sounds, and had urine incontinence compared to the survivor patients. The mortality patients also had acute kidney injury, higher potassium, blood sugar, liver function test, and lactate level. The results of multiple logistic regression demonstrated that SBP < 90 mmHg, dyspnea, blood sugar > 140 mg/dl, and HCO3 < 20.6 mmHg were independent predictors of in-hospital mortality. Regardless of the pattern of the use of illicit drugs, the predictors allow for risk stratification and determining the optimal treatment.

Self-Administration of Entactogen Psychostimulants Dysregulates Gamma-Aminobutyric Acid (GABA) and Kappa Opioid Receptor Signaling in the Central Nucleus of the Amygdala of Female Wistar Rats

Male rats escalate intravenous self-administration of entactogen psychostimulants, 3,4-methylenedioxymethcathinone (methylone) and 3,4-methylenedioxymethamphetamine (MDMA) under extended access conditions, as with typical psychostimulants. Here, we investigated whether female rats escalate self-administration of methylone, 3,4-methylenedioxypentedrone (pentylone), and MDMA and then studied consequences of MDMA and pentylone self-administration on GABAA receptor and kappa opioid receptor (KOR) signaling in the central nucleus of the amygdala (CeA), a brain area critically dysregulated by extended access self-administration of alcohol or cocaine. Adult female Wistar rats were trained to self-administer methylone, pentylone, MDMA (0.5 mg/kg/infusion), or saline-vehicle using a fixed-ratio 1 response contingency in 6-h sessions (long-access: LgA) followed by progressive ratio (PR) dose-response testing. The effects of pentylone-LgA, MDMA-LgA and saline on basal GABAergic transmission (miniature post-synaptic inhibitory currents, mIPSCs) and the modulatory role of KOR at CeA GABAergic synapses were determined in acute brain slices using whole-cell patch-clamp. Methylone-LgA and pentylone-LgA rats similarly escalated their drug intake (both obtained more infusions compared to MDMA-LgA rats), however, pentylone-LgA rats reached higher breakpoints in PR tests. At the cellular level, baseline CeA GABA transmission was markedly elevated in pentylone-LgA and MDMA-LgA rats compared to saline-vehicle. Specifically, pentylone-LgA was associated with increased CeA mIPSC frequency (GABA release) and amplitude (post-synaptic GABAA receptor function), while mIPSC amplitudes (but not frequency) was larger in MDMA-LgA rats compared to saline rats. In addition, pentylone-LgA and MDMA-LgA profoundly disrupted CeA KOR signaling such as both KOR agonism (1 mM U50488) and KOR antagonism (200 nM nor-binaltorphimine) decreased mIPSC frequency suggesting recruitment of non-canonical KOR signaling pathways. This study confirms escalated self-administration of entactogen psychostimulants under LgA conditions in female rats which is accompanied by increased CeA GABAergic inhibition and altered KOR signaling. Collectively, our study suggests that CeA GABA and KOR mechanisms play a critical role in entactogen self-administration like those observed with escalation of alcohol or cocaine self-administration.

Development and validation of a rapid LC-MS/MS method for the detection of 182 novel psychoactive substances in whole blood

Introduction

The analysis of novel psychoactive substances (NPS) represents a challenge in forensic toxicology, due to the high number of compounds characterized by different structures and physicochemical properties both among different subclasses and within a single subclass of NPS. The aim of the present work is the development and validation of a targeted liquid chromatography tandem mass spectrometry (LC‐MS/MS) method for the detection of NPS in whole blood.

Materials and methods

A protein‐precipitation based LC‐MS/MS method for the detection of more than 180 NPS was developed and validated by assessing the following parameters: selectivity, linearity, accuracy, precision, limit of detection (LOD) and of quantification (LOQ) recovery, and matrix effect. Then, the method was applied to real forensic samples.

Results

The method allowed the identification of 132 synthetic cannabinoids, 22 synthetic opioids, and 28 substances among synthetic cathinones, stimulants, and other drugs. Validation was successfully achieved for most of the compounds. Linearity was in the range of 0.25–10 ng/ml for synthetic cannabinoids and 0.25–25 ng/ml for other drugs. Accuracy and precision were acceptable according to international guidelines. Three cases tested positive for fentanyl and ketamine, in the setting of emergency room administration.

Conclusions

The present methodology represents a fast, not expensive, wide‐panel method for the analysis of more than 180 NPS by LC‐MS/MS, which can be profitably applied both in a clinical context and in postmortem toxicology.

α-PPP and its derivatives are selective partial releasers at the human norepinephrine transporter: A pharmacological characterization of interactions between pyrrolidinopropiophenones and high and low affinity monoamine transporters

While classical cathinones, such as methcathinone, have been shown to be monoamine releasing agents at human monoamine transporters, the subgroup of α-pyrrolidinophenones has thus far solely been characterized as monoamine transporter reuptake inhibitors. Herein, we report data from previously undescribed α-pyrrolidinopropiophenone (α-PPP) derivatives and compare them with the pharmacologically well-researched α-PVP (α-pyrrolidinovalerophenone). Radiotracer-based in vitro uptake inhibition assays in HEK293 cells show that the investigated α-PPP derivatives inhibit the human high-affinity transporters of dopamine (hDAT) and norepinephrine (hNET) in the low micromolar range, with α-PVP being ten times more potent. Similar to α-PVP, no relevant pharmacological activity was found at the human serotonin transporter (hSERT). Unexpectedly, radiotracer-based in vitro release assays reveal α-PPP, MDPPP and 3Br-PPP, but not α-PVP, to be partial releasing agents at hNET (EC50 values in the low micromolar range). Furthermore, uptake inhibition assays at low-affinity monoamine transporters, i.e., the human organic cation transporters (hOCT) 1-3 and human plasma membrane monoamine transporter (hPMAT), bring to light that all compounds inhibit hOCT1 and 2 (IC50 values in the low micromolar range) while less potently interacting with hPMAT and hOCT3. In conclusion, this study describes (i) three new hybrid compounds that efficaciously block hDAT while being partial releasers at hNET, and (ii) highlights the interactions of α-PPP-derivatives with low-affinity monoamine transporters, giving impetus to further studies investigating the interaction of drugs of abuse with OCT1-3 and PMAT.

Discriminative-Stimulus Effects of Synthetic Cathinones in Squirrel Monkeys

BACKGROUND

Synthetic cathinones display overlapping behavioral effects with psychostimulants (e.g., methamphetamine [MA]) and/or entactogens (e.g., 3,4-methylenedioxymethaphetamine [MDMA])-presumably reflecting their dopaminergic and/or serotonergic activity. The discriminative stimulus effects of MDMA thought to be mediated by such activity have been well characterized in rodents but have not been fully examined in nonhuman primates.

METHODS

The present studies were conducted to systematically evaluate the discriminative stimulus effects of 5 abused synthetic cathinones (methylenedioxypyrovalerone [MDPV], α-pyrrolidinovalerophenone [α-PVP], methcathinone [MCAT], mephedrone, and methylone) in adult male squirrel monkeys trained to distinguish intramuscular injections of MA (0.1 mg/kg; n = 4) or MDMA (0.6 mg/kg; n = 4) from vehicle.

RESULTS

Each training drug produced dose-dependent effects and, at the highest dose, full substitution. MDMA produced predominantly vehicle-like responding in the MA-trained group, whereas the highest dose of MA (0.56 mg/kg) produced partial substitution (approximately 90% appropriate lever responding in one-half of the subjects) in the MDMA-trained group. MDPV, α-PVP, and MCAT produced full substitution in MA-trained subjects, but, at the same or higher doses, only substituted for MDMA in one-half of the subjects, consistent with primarily dopaminergically mediated interoceptive effects. In contrast, mephedrone and methylone fully substituted in MDMA-trained subjects but failed to fully substitute for the training drug in MA-trained subjects, suggesting a primary role for serotonergic actions in their interoceptive effects.

CONCLUSIONS

These findings suggest that differences in the interoceptive effects of synthetic cathinones in nonhuman primates reflect differing compositions of monoaminergic actions that also may mediate their subjective effects in humans.

When an obscurity becomes trend: social-media descriptions of tianeptine use and associated atypical drug use

Background: Originally believed to be an atypical antidepressant acting at serotonin transporters, tianeptine is now known to also be an atypical agonist at mu-opioid receptors. Its nonmedical use may be increasing amidst the broader context of novel drug and supplement use.Objectives: To analyze social-media text from current, former, and prospective tianeptine users for better understanding of their conceptualizations of tianeptine, motives for and patterns of use, and reported benefits and harms.Methods: Reddit posts were obtained and thematically coded; additional quantitative analyses were conducted.Results: A total of 210 posts mentioning tianeptine were made between 2012 and 2020. Eighteen thematic categories were identified, 10 of which were consistent with expected themes. Two independent raters coded all text, generating 1,382 unique codes, of which 1,090 were concordant (78.9% interrater agreement). Tianeptine use was frequently associated with use of other drugs, particularly kratom, phenibut, and racetams. People conceptualized and variously used tianeptine as an opioid, antidepressant, and "nootropic" (cognitive enhancer). Between 2014 and 2020, mentions of positive effects decreased, while mentions of adverse effects and withdrawal increased. Motivations for use included substitution or withdrawal mitigation for other drugs (especially opioids) and for kratom itself; self-treatment for psychiatric symptoms; and improvement of quality of life, mood, or performance. Descriptions of tolerance, withdrawal, and addiction were evident. Intravenous use was rare and strongly discouraged, with detrimental effects described.Conclusion: Tianeptine is recognized as an opioid (though not only an opioid) in online communities. Posts describe benefits, acute risks, and patterns of co-use that warrant greater clinical attention.

Effects of Hydroxylated Mephedrone Metabolites on Monoamine Transporter Activity in vitro

Mephedrone is a largely abused psychostimulant. It elicits the release of monoamines via the high affinity transporters for dopamine (DAT), norepinephrine (NET) and serotonin (SERT). Stereoselective metabolic reactions are involved in the inactivation and the elimination of its chemical structure. However, during these processes, several structures are generated and some of them have been reported to be still pharmacologically active. In this study 1) we have newly synthetized several putative mephedrone metabolites, 2) compared their activity at monoamine transporters, 3) generated quantitative structure activity relationships, and 4) exploited the chemical structure of the putative metabolites to screen a urine sample from a drug user and dissect mephedrone metabolism. We have found that most of the tested metabolites are weak inhibitors of monoamine transporters and that all of them are more potent at DAT and NET in comparison to SERT. The only exception is represented by the COOH-metabolite which shows no pharmacological activity at all three monoamine transporters. The enantioselectivity of mephedrone and its metabolites is present mainly at SERT, with only minor effects at DAT and NET being introduced when the β-keto group is reduced to an OH-group. Importantly, while at DAT the putative metabolites did not show changes in inhibitory potencies, but rather changes in their substrate/blocker profile, at SERT they showed mainly changes in inhibitory potencies. Molecular modeling suggests that the hydrophobic nature of a specific SERT subpocket may be involved in such loss of affinity. Finally, the assessment of the putative metabolites in one urine sample of mephedrone user displayed two previously uncharacterized metabolites, 4-COOH-nor-mephedrone (4-COOH-MC) and dihydro-4- nor-mephedrone (dihydro-4-MC). These results confirm and expand previous studies highlighting the importance of the stereochemistry in the pharmacodynamics of phase-1 metabolites of mephedrone, established their structure-activity relationships at DAT, NET and SERT and pave the way for a systematic dissection of mephedrone metabolic routes. Given the number of structures found having residual and modified pharmacological profiles, these findings may help in understanding the complex subjective effects of administered mephedrone. Moreover, the dissection of mephedrone metabolic routes may help in developing new therapies for treating psychostimulants acute intoxications.

Eutylone and Its Structural Isomers Interact with Monoamine Transporters and Induce Locomotor Stimulation

Synthetic cathinones are a class of new psychoactive substances that induce psychostimulant effects and pose risk for hospitalizations, overdose, and death. At the present time, derivatives of the synthetic cathinone, methylone, are being confiscated in nonmedical (i.e., recreational) drug markets worldwide. In particular, eutylone is a newly emerging methylone analog that possesses ethyl groups at the α-carbon and amine positions. Little information is available about the pharmacological effects of eutylone, but based on its structure, we surmised that the compound interacts with monoamine transporters in the brain. To test this hypothesis, we compared the effects of eutylone and its structural isomers, dibutylone and pentylone, using in vitro transporter assays in rat brain synaptosomes and in vivo locomotor activity assessments in mice. All drugs displayed dose-related inhibition of [³H]neurotransmitter uptake at dopamine transporters (DAT) and norepinephrine transporters (NET), but effects at DAT were 10-fold more potent (IC₅₀ = 120 nM). Eutylone and pentylone inhibited uptake at serotonin transporters (SERT), while dibutylone did not. Additionally, eutylone and pentylone displayed weak partial releasing actions at SERT which achieved 50% of maximal response. All drugs stimulated dose-related locomotion in mice, and eutylone was most potent and efficacious in this regard (ED₅₀ = 2 mg/kg, sc). Our results demonstrate that eutylone is a hybrid transporter compound with uptake inhibition properties at DAT and NET but substrate activity at SERT. The effects of eutylone are similar to those produced by pentylone, which suggests that eutylone will exhibit abuse liability and pose risks for psychostimulant side-effects in human users.

[Method for determination the action of psychoactive agents on the central nervous system based on the molecular docking method]

A large number of narcotic substances are currently being synthesized. In 2018, at least one drug with a new chemical formula was created and distributed around the world every week. In a number of countries, it became necessary to change legislation to optimize the regulation of drug trafficking to speed up and simplify the procedure for adding chemical compounds to the list of drugs. The new global legal and regulatory terminology has made it possible to approach the definition of «psychoactive substance» from a legal and medical point of view. The legislative definitions of medical organizations have been clarified that have determined the main features of new psychoactive substances: the possibility of influencing the human nervous system and the ability to form addictive behavior. The problem in the production of forensic medical examination is the answer to the question about the state of drug intoxication (poisoning) of a person from the action of a new psychoactive substance in the absence of information about the clinical picture of intoxication (poisoning). The proposed method of molecular docking allows confirming the possibility of a chemical substance acting on the human nervous system to determine the similarity with the effects of drugs and to consider the properties of a chemical compound as the properties of a "new psychoactive substance". Molecular docking - modeling the interaction of a bio-target - a human receptor protein sensitive to a drug with a ligand - a drug. The method allows to determine the fundamental possibility of a chemical reaction between molecules, as well as to estimate the reaction energy for the isolation of the most chemically active ligands.

Drug checking identifies counterfeit alprazolam tablets

BACKGROUND

Non-prescribed benzodiazepine use is increasing in North America, especially among youth. Owing to increasing demand, counterfeit benzodiazepine tablets are mass-produced in clandestine, unregulated environments and sold as legitimate pharmaceuticals. This study aimed to examine the contents of counterfeit alprazolam tablets available in the unregulated drug market in British Columbia, Canada.

METHODS

Data were collected from an ongoing evaluation of a community drug checking service in British Columbia between October 2017 and March 2020. The service operates point-of-care in harm reduction sites using Fourier-transform infrared (FTIR) spectrometers coupled with fentanyl and benzodiazepine immunoassay strips. A subset of samples were sent for confirmatory analysis at partner laboratories and underwent one or more of gas chromatography/mass spectrometry, liquid chromatography/mass spectrometry, and quantitative nuclear magnetic resonance analysis.

RESULTS

During the study period, 10,814 total samples were submitted for drug checking, 139 of which were expected to be Xanax (alprazolam) or generic tablets and met the criteria for inclusion. Using FTIR analysis, 33 (23.7 %) samples were identified to contain alprazolam. Only 122 samples were checked using benzodiazepine immunoassay strips and 88 (72.1 %) tested positive. Qualitative results from the 20 samples submitted for confirmatory analysis included various new psychoactive substances and only 2 contained only alprazolam.

CONCLUSIONS

Our findings provide evidence that Xanax tablets obtained from the unregulated drug market are likely to be counterfeit and may not contain alprazolam. Drug checking offers people who use drugs a valuable means to determine the contents of their substances; however, limitations of point-of-care technologies must be considered.

The psychoactive aminoalkylbenzofuran derivatives, 5-APB and 6-APB, mimic the effects of 3,4-methylenedioxyamphetamine (MDA) on monoamine transmission in male rats

RATIONALE

The nonmedical use of new psychoactive substances (NPS) is a worldwide public health concern. The so-called "benzofury" compounds, 5-(2-aminopropyl)benzofuran (5-APB) and 6-(2-aminopropyl)benzofuran (6-APB), are NPS with stimulant-like properties in human users. These substances are known to interact with monoamine transporters and 5-HT receptors in transfected cells, but less is known about their effects in animal models.

METHODS

Here, we used in vitro monoamine transporter assays in rat brain synaptosomes to characterize the effects of 5-APB and 6-APB, together with their N-methyl derivatives 5-MAPB and 6-MAPB, in comparison with 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA). In vivo neurochemical and behavioral effects of 5-APB (0.3 and 1.0 mg/kg, i.v.) and 6-APB (0.3 and 1.0 mg/kg, i.v.) were assessed in comparison with MDA (1.0 and 3.0 mg/kg, i.v.) using microdialysis sampling in the nucleus accumbens of conscious male rats.

RESULTS

All four benzofuran derivatives were substrate-type releasers at dopamine transporters (DAT), norepinephrine transporters (NET), and serotonin transporters (SERT) with nanomolar potencies, similar to the profile of effects produced by MDA and MDMA. However, the benzofurans were at least threefold more potent than MDA and MDMA at evoking transporter-mediated release. Like MDA, both benzofurans induced dose-related elevations in extracellular dopamine and serotonin in the brain, but benzofurans were more potent than MDA. The benzofuran derivatives also induced profound behavioral activation characterized by forward locomotion which lasted for at least 2 h post-injection.

CONCLUSIONS

Overall, benzofurans are more potent than MDA in vitro and in vivo, producing sustained stimulant-like effects in rats. These data suggest that benzofuran-type compounds may have abuse liability and could pose risks for adverse effects, especially if used in conjunction with abused drugs or medications which enhance monoamine transmission in the brain.

Understanding the UK Psychoactive Substances Act

This review paper is based on a talk given at the British Pharmaceutical Society Winter Meeting in 2018 derived from the Home Office Report on the workings of the UK Psychoactive Substances Act (PSA) published in November 2018. The review deals with the context in which the PSA 2016 arose and how this piece of legislation differs from other UK drug regulations. It attempts to put the PSA in context with other control schemes being instituted around the world and to assess the success of the Act in its first 2 years of implementation. For more details the reader is referred to Review of the Psychoactive Substances Act 2016, Home Office, November 2018.

Differential effects of synthetic psychoactive cathinones and amphetamine stimulants on the gut microbiome in mice

The list of pharmacological agents that can modify the gut microbiome or be modified by it continues to grow at a high rate. The greatest amount of attention on drug-gut microbiome interactions has been directed primarily at pharmaceuticals used to treat infection, diabetes, cardiovascular conditions and cancer. By comparison, drugs of abuse and addiction, which can powerfully and chronically worsen human health, have received relatively little attention in this regard. Therefore, the main objective of this study was to characterize how selected synthetic psychoactive cathinones (aka “Bath Salts”) and amphetamine stimulants modify the gut microbiome. Mice were treated with mephedrone (40 mg/kg), methcathinone (80 mg/kg), methamphetamine (5 mg/kg) or 4-methyl-methamphetamine (40 mg/kg), following a binge regimen consisting of 4 injections at 2h intervals. These drugs were selected for study because they are structural analogs that contain a β-keto substituent (methcathinone), a 4-methyl group (4-methyl-methamphetamine), both substituents (mephedrone) or neither (methamphetamine). Mice were sacrificed 1, 2 or 7 days after treatment and DNA from caecum contents was subjected to 16S rRNA sequencing. We found that all drugs caused significant time- and structure-dependent alterations in the diversity and taxonomic structure of the gut microbiome. The two phyla most changed by drug treatments were Firmicutes (methcathinone, 4-methyl-methamphetamine) and Bacteriodetes (methcathinone, 4-methyl-methamphetamine, methamphetamine, mephedrone). Across time, broad microbiome changes from the phylum to genus levels were characteristic of all drugs. The present results signify that these selected psychoactive drugs, which are thought to exert their primary effects within the CNS, can have profound effects on the gut microbiome. They also suggest new avenues of investigation into the possibility that gut-derived signals could modulate drug abuse and addiction via altered communication along the gut-brain axis.

2-Aminoindan and its ring-substituted derivatives interact with plasma membrane monoamine transporters and α2-adrenergic receptors

RATIONALE

Over the last decade, many new psychostimulant analogues have appeared on the recreational drug market and most are derivatives of amphetamine or cathinone. Another class of designer drugs is derived from the 2-aminoindan structural template. Several members of this class, including the parent compound 2-aminoindan (2-AI), have been sold as designer drugs. Another aminoindan derivative, 5-methoxy-2-aminoindan (5-MeO-AI or MEAI), is the active ingredient in a product marketed online as an alcohol substitute.

METHODS

Here, we tested 2-AI and its ring-substituted derivatives 5-MeO-AI, 5-methoxy-6-methyl-2-aminoindan (MMAI), and 5,6-methylenedioxy-2-aminoindan (MDAI) for their abilities to interact with plasma membrane monoamine transporters for dopamine (DAT), norepinephrine (NET) and serotonin (SERT). We also compared the binding affinities of the aminoindans at 29 receptor and transporter binding sites.

RESULTS

2-AI was a selective substrate for NET and DAT. Ring substitution increased potency at SERT while reducing potency at DAT and NET. MDAI was moderately selective for SERT and NET, with tenfold weaker effects on DAT. 5-MeO-AI exhibited some selectivity for SERT, having sixfold lower potency at NET and 20-fold lower potency at DAT. MMAI was highly selective for SERT, with 100-fold lower potency at NET and DAT. The aminoindans had relatively high affinity for α₂-adrenoceptor subtypes. 2-AI had particularly high affinity for α_2C receptors (K_i = 41 nM) and slightly lower affinity for the α_2A (K_i = 134 nM) and α_2B (K_i = 211 nM) subtypes. 5-MeO-AI and MMAI also had moderate affinity for the 5-HT_2B receptor.

CONCLUSIONS

2-AI is predicted to have (+)-amphetamine-like effects and abuse potential whereas the ring-substituted derivatives may produce 3,4-methylenedioxymethamphetamine (MDMA)-like effects but with less abuse liability.

Cognitive deficits and neurotoxicity induced by synthetic cathinones: is there a role for neuroinflammation?

RATIONALE

The number of synthetic derivatives of cathinone, the primary psychoactive alkaloid found in Catha edulis (khat), has risen exponentially in the past decade. Synthetic cathinones (frequently referred to as "bath salts") produce adverse cognitive and behavioral sequelae, share similar pharmacological mechanisms of action with traditional psychostimulants, and may therefore trigger similar cellular events that give rise to neuroinflammation and neurotoxicity.

OBJECTIVES

In this review, we provide a brief overview of synthetic cathinones, followed by a summary of cognitive deficits in animals and humans that have been documented following acute or repeated exposure. We also summarize growing evidence from in vitro and in vivo studies for synthetic cathinone-induced neurotoxicity, and provide a working hypothetic model of potential cellular mechanisms.

RESULTS

Synthetic cathinones produce varying effects on markers of monoaminergic terminal function and can increase the formation of reactive oxygen and nitrogen species, induce apoptotic signaling, and cause neurodegeneration and cytotoxicity. We hypothesize that these effects result from biochemical events similar to those induced by traditional psychostimulants. However, empirical evidence for the ability of synthetic cathinones to induce neuroinflammatory processes is currently lacking.

CONCLUSIONS

Like their traditional psychostimulant counterparts, synthetic cathinones appear to induce neurocognitive dysfunction and cytotoxicity, which are dependent on drug type, dose, frequency, and time following exposure. However, additional studies on synthetic cathinone-induced neuroinflammation are clearly needed, as are investigations into the neurochemical and neuroimmune mechanisms underlying their neurotoxic effects. Such endeavors may lead to novel therapeutic avenues to promote recovery in habitual synthetic cathinone users.

Dissociation between hypothermia and neurotoxicity caused by mephedrone and methcathinone in TPH2 knockout mice

RATIONALE

Mephedrone is a commonly abused constituent of "bath salts" and has many pharmacological effects in common with methamphetamine. Despite their structural similarity, mephedrone differs significantly from methamphetamine in its effects on core body temperature and dopamine nerve endings. The reasons for these differences remain unclear.

OBJECTIVES

Mephedrone elicits a transient hypothermia which may provide intrinsic neuroprotection against methamphetamine-like toxicity to dopamine nerve endings. Furthermore, evidence in the literature suggests that this hypothermia is mediated by serotonin. By utilizing transgenic mice devoid of brain serotonin, we determined the contribution of this neurotransmitter to changes in core body temperature as well as its possible role in protecting against neurotoxicity. The effects of methcathinone and 4-methyl-methamphetamine, two structural analogs of mephedrone and methamphetamine, were also evaluated in these mice.

RESULTS

The hypothermia induced by mephedrone and methcathinone in wild-type mice was not observed in mice lacking brain serotonin. Despite preventing drug-induced hypothermia, the lack of serotonin did not alter the neurotoxic profiles of the test drugs.

CONCLUSIONS

Serotonin is a key mediator of pharmacological hypothermia induced by mephedrone and methcathinone, but these body temperature effects do not contribute to dopamine nerve ending damage observed in mice following treatment with mephedrone, methcathinone or 4-methyl-methamphetamine. Thus, the key component of methamphetamine neurotoxicity lacking in mephedrone remains to be elucidated.

The synthetic cathinones, butylone and pentylone, are stimulants that act as dopamine transporter blockers but 5-HT transporter substrates

RATIONALE

Synthetic cathinones continue to emerge in recreational drug markets worldwide. 1-(1,3-Benzodioxol-5-yl)-2-(methylamino)butan-1-one (butylone) and 1-(1,3-benzodioxol-5-yl)-2-(methylamino)pentan-1-one (pentylone) are derivatives of the cathinone compound, 1-(1,3-benzodioxol-5-yl)-2-(methylamino)propan-1-one (methylone), that are being detected in drug products and human casework.

OBJECTIVES

The purpose of the present study was to examine the neuropharmacology of butylone and pentylone using in vitro and in vivo methods.

METHODS

In vitro uptake and release assays were carried out in rat brain synaptosomes and in cells expressing human dopamine transporters (DAT) and 5-HT transporters (SERT). In vivo microdialysis was performed in the nucleus accumbens of conscious rats to assess drug-induced changes in neurochemistry.

RESULTS

Butylone and pentylone were efficacious uptake blockers at DAT and SERT, though pentylone was more DAT-selective. Both drugs acted as transporter substrates that evoked release of [³H]5-HT at SERT, while neither evoked release at DAT. Consistent with the release data, butylone and pentylone induced substrate-associated inward currents at SERT but not DAT. Administration of butylone or pentylone to rats (1 and 3 mg/kg, i.v.) increased extracellular monoamines and motor activity, but pentylone had weaker effects on 5-HT and stronger effects on motor stimulation.

CONCLUSIONS

Our data demonstrate that increasing the α-carbon chain length of methylone creates "hybrid" transporter compounds which act as DAT blockers but SERT substrates. Nevertheless, butylone and pentylone elevate extracellular dopamine and stimulate motor activity, suggesting both drugs possess significant risk for abuse.

Bath salts and polyconsumption: in search of drug-drug interactions

BACKGROUND AND RATIONALE

Polydrug use is a widespread phenomenon, especially among adolescents and young adults. Synthetic cathinones are frequently consumed in combination with other drugs of abuse. However, there is very little information regarding the consequences of this specific consumption pattern.

OBJECTIVES

The aim of this review is to introduce this topic and highlight the gaps in the existing literature. In three different sections, we focus on specific interactions of synthetic cathinones with alcohol, cannabinoids, and the stimulants nicotine and cocaine. We then dedicate a section to the existence of sex and gender differences in the effects of synthetic cathinones and the long-term psychophysiological consequences of adolescent and prenatal exposure to these drugs.

MAJOR FINDINGS

Epidemiological studies, case reports, and results obtained in animal models point to the existence of pharmacological and pharmacokinetic interactions between synthetic cathinones and other drugs of abuse. This pattern of polyconsumption can cause the potentiation of negative effects, and the dissociation between objective and subjective effects can increase the combined use of the drugs and the risk of toxicity leading to serious health problems. Certain animal studies indicate a higher vulnerability and effect of cathinones in females. In humans, most of the users are men and case reports show long-term psychotic symptoms after repeated use.

CONCLUSIONS

The co-use of synthetic cathinones and the other drugs of abuse analyzed indicates potentiation of diverse effects including dependence and addiction, neurotoxicity, and impaired cognition and emotional responses. The motivations for and effects of synthetic cathinone use appear to be influenced by sex/gender. The long-term consequences of their use by adolescents and pregnant women deserve further investigation.

DARK Classics in Chemical Neuroscience: Aminorex Analogues

Aminorex (5-phenyl-4,5-dihydro-1,3-oxazol-2-amine) and 4-methylaminorex (4-methyl-5-phenyl-4,5-dihydro-1,3-oxazol-2-amine) are psychostimulants that have long been listed in Schedules IV and I of the UN Convention on Psychotropic Substances of 1971. However, a range of psychoactive analogues exist that are not internationally controlled and therefore often classified as new psychoactive substances (NPS). Aminorex analogues encompass failed pharmaceuticals that reemerged as drugs of abuse, and newly synthesized substances that were solely designed for recreational use by clandestine chemists. NPS, sometimes also referred to as "designer drugs" in alignment with a phenomenon arising in the early 1980s, serve as alternatives to controlled drugs. Aminorex and its derivatives interact with monoaminergic neurotransmission by interfering with the function of monoamine transporters. Hence, these compounds share pharmacological and neurochemical similarities with amphetamines and cocaine. The consumption of aminorex, 4-methylaminorex and 4,4'-dimethylaminorex (4-methyl-5-(4-methylphenyl)-4,5-dihydro-1,3-oxazol-2-amine) has been associated with adverse events including death, bestowing an inglorious fame on aminorex-derived drugs. In this Review, a historical background is presented, as well as an account of the pharmacodynamic and pharmacokinetic properties of aminorex and various analogues. Light is shed on their misuse as drug adulterants of well-established drugs on the market. This Review not only provides a detailed overview of an abused substance-class, but also emphasizes the darkest aspect of the NPS market, i.e., deleterious side effects that arise from the ingestion of certain NPS, as knowledge of the pharmacology, the potency, or the identity of the active ingredients remains obscure to NPS users.

The psychostimulant (±)-cis-4,4'-dimethylaminorex (4,4'-DMAR) interacts with human plasmalemmal and vesicular monoamine transporters

(±)-cis-4,4'-Dimethylaminorex (4,4'-DMAR) is a new psychoactive substance (NPS) that has been associated with 31 fatalities and other adverse events in Europe between June 2013 and February 2014. We used in vitro uptake inhibition and transporter release assays to determine the effects of 4,4'-DMAR on human high-affinity transporters for dopamine (DAT), norepinephrine (NET) and serotonin (SERT). In addition, we assessed its binding affinities to monoamine receptors and transporters. Furthermore, we investigated the interaction of 4,4'-DMAR with the vesicular monoamine transporter 2 (VMAT2) in rat phaeochromocytoma (PC12) cells and synaptic vesicles prepared from human striatum. 4,4'-DMAR inhibited uptake mediated by human DAT, NET or SERT, respectively in the low micromolar range (IC₅₀ values < 2 μM). Release assays identified 4,4'-DMAR as a substrate type releaser, capable of inducing transporter-mediated reverse transport via DAT, NET and SERT. Furthermore, 4,4'-DMAR inhibited both the rat and human isoforms of VMAT2 at a potency similar to 3,4-methylenedioxymethylamphetamine (MDMA). This study identified 4,4'-DMAR as a potent non-selective monoamine releasing agent. In contrast to the known effects of aminorex and 4-methylaminorex, 4,4'-DMAR exerts profound effects on human SERT. The latter finding is consistent with the idea that fatalities associated with its abuse may be linked to monoaminergic toxicity including serotonin syndrome. The activity at VMAT2 suggests that chronic abuse of 4,4'-DMAR may result in long-term neurotoxicity.

Overview of Monoamine Transporters

The dopamine (DAT), serotonin (SERT), and norepinephrine (NET) transporters, which are collectively referred to as monoamine transporters (MATs), play significant roles in regulating the neuronal response to these neurotransmitters. MATs terminate the action of these neurotransmitters by translocating them from the synaptic space into the presynaptic neurons. These three transmitters are responsible for controlling a number of physiological, emotional, and behavioral functions, with their transporters being the site of action of drugs employed for the treatment of a variety of conditions, including depression, anxiety, ADHD, schizophrenia, and psychostimulant abuse. Provided in this unit is information on the localization and regulation of MATs and the structural components of these proteins most responsible for the translocation process. Also included is a brief description of the evolution of ligands that interact with these transporters, as well as current theories concerning the pharmacological effects of substances that interact with these sites, including the molecular mechanisms of action of uptake inhibitors and allosteric modulators. Data relating to the presence, structure, and functions of allosteric modulators are included as well. The aim of this review is to provide background information on MATs to those who are new to this field, with a focus on the therapeutic potential of compounds that interact with these substrate transport sites. © 2017 by John Wiley & Sons, Inc.

Utility of Nonhuman Primates in Substance Use Disorders Research

Substance use disorders (i.e., drug addiction) constitute a global and insidious public health issue. Preclinical biomedical research has been invaluable in elucidating the environmental, biological, and pharmacological determinants of drug abuse and in the process of developing innovative pharmacological and behavioral treatment strategies. For more than 70 years, nonhuman primates have been utilized as research subjects in biomedical research related to drug addiction. There are already several excellent published reviews highlighting species differences in both pharmacodynamics and pharmacokinetics between rodents and nonhuman primates in preclinical substance abuse research. Therefore, the aim of this review is to highlight three advantages of nonhuman primates as preclinical substance abuse research subjects. First, nonhuman primates offer technical advantages in experimental design compared to other laboratory animals that afford unique opportunities to promote preclinical-to-clinical translational research. Second, these technical advantages, coupled with the relatively long lifespan of nonhuman primates, allows for pairing longitudinal drug self-administration studies and noninvasive imaging technologies to elucidate the biological consequences of chronic drug exposure. Lastly, nonhuman primates offer advantages in the patterns of intravenous drug self-administration that have potential theoretical implications for both the neurobiological mechanisms of substance use disorder etiology and in the drug development process of pharmacotherapies for substance use disorders. We conclude with potential future research directions in which nonhuman primates would provide unique and valuable insights into the abuse of and addiction to novel psychoactive substances.

The Novel Psychoactive Substances in the UK Project: empirical and conceptual review work to produce research recommendations

Background

Although illegal drug use has largely been declining in the UK over the past decade, this period has witnessed the emergence of a range of novel psychoactive substances (NPS) (‘legal highs’). These are new, mostly synthetic, substances that mimic the effects of existing drugs). Despite there being many causes for concern in relation to NPS, there has been little prior study of the burden associated with their use in public health terms. Clarity is lacking on research priorities in this rapidly developing literature.

Objectives

To inform the development of public health intervention research on NPS by reviewing existing data on their use, associated problems and potential responses to such problems.

Design

A scoping review and narrative synthesis of selected bodies of evidence was undertaken to summarise and evaluate what is known about NPS use and the related harms of, and responses to, such use. Relevant literature was identified from electronic databases (covering January 2006 to June 2016 inclusive), Google (Google Inc., Mountain View, CA, USA), relevant websites and online drug forums and by contacting experts. Articles were included if they were primary studies, secondary studies involving the analysis and interpretation of primary research or discussion papers. A conceptual framework postulating an evidence-informed public health approach to NPS use in the UK was developed through a pragmatic literature review, the iterative development of concepts and finalisation in light of the results from the empirical review work. The process also involved feedback from various stakeholders. Research recommendations were developed from both strands of work.

Results

A total of 995 articles were included in the scoping review, the majority of which related to individual-level health-related adverse effects attributable to NPS use. The prevalence of lifetime NPS use varied widely between (e.g. with higher prevalence in young males) and within population subgroups. The most commonly reported adverse effects were psychiatric/other neurological, cardiovascular, renal and gastrointestinal manifestations, and there is limited evidence available on responses. In these and other respects, available evidence is at an early stage of development. Initial evidence challenges the view that NPS should be treated differently from other illicit drugs. The conceptual framework indicated that much of the evidence that would be useful to inform public health responses does not yet exist. We propose a systems-based prevention approach that develops existing responses, is multilevel and life course informed in character, and emphasises commonalities between NPS and other legal and illegal drug use. We make 20 recommendations for research, including nine key recommendations.

Limitations

Scoping reviews do not interrogate evidence in depth, and the disjunction between the scoping review and the conceptual framework findings is worthy of careful attention.

Conclusions

Key research recommendations build on those that have previously been made and offer more evidence-based justification and detail, as previous recommendations have not yet been acted on. The case for decision-making on commissioning new research based on these recommendations is both strong and urgent.

Future work

The validity of recommendations generated through this project could be enhanced via further work with research commissioners, policy-makers, researchers and the public.

Study registration

The systematic review element of this study is registered as PROSPERO CRD42016026415.

Funding

The National Institute for Health Research Public Health Research programme.

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.

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.

Structure-Activity Relationships of Substituted Cathinones, with Transporter Binding, Uptake, and Release

Synthetic cathinones are components of "bath salts" and have physical and psychologic side effects, including hypertension, paranoia, and hallucinations. Here, we report interactions of 20 "bath salt" components with human dopamine, serotonin, and norepinephrine transporters [human dopamine transporter (hDAT), human serotonin transporter (hSERT), and human norepinephrine transporter (hNET), respectively] heterologously expressed in human embryonic kidney 293 cells. Transporter inhibitors had nanomolar to micromolar affinities (K_i values) at radioligand binding sites, with relative affinities of hDAT>hNET>hSERT for α-pyrrolidinopropiophenone (α-PPP), α-pyrrolidinobutiophenone, α-pyrrolidinohexiophenone, 1-phenyl-2-(1-pyrrolidinyl)-1-heptanone, 3,4-methylenedioxy-α-pyrrolidinopropiophenone, 3,4-methylenedioxy-α-pyrrolidinobutiophenone, 4-methyl-α-pyrrolidinopropiophenone, α-pyrrolidinovalerophenone, 4-methoxy-α-pyrrolidinovalerophenone, α-pyrrolidinopentiothiophenone (alpha-PVT), and α-methylaminovalerophenone, and hDAT>hSERT>hNET for methylenedioxypentedrone. Increasing the α-carbon chain length increased the affinity and potency of the α-pyrrolidinophenones. Uptake inhibitors had relative potencies of hDAT>hNET>hSERT except α-PPP and α-PVT, which had highest potencies at hNET. They did not induce [³H]neurotransmitter release. Substrates can enter presynaptic neurons via transporters, and the substrates methamphetamine and 3,4-methylenedioxymethylamphetamine are neurotoxic. We determined that 3-fluoro-, 4-bromo-, 4-chloro-methcathinone, and 4-fluoroamphetamine were substrates at all three transporters; 5,6-methylenedioxy-2-aminoindane (MDAI) and 4-methylethcathinone (4-MEC) were substrates primarily at hSERT and hNET; and 3,4-methylenedioxy-N-ethylcathinone (ethylone) and 5-methoxy-methylone were substrates only at hSERT and induced [³H]neurotransmitter release. Significant correlations between potencies for inhibition of uptake and for inducing release were observed for these and additional substrates. The excellent correlation of efficacy at stimulating release versus K_i/IC₅₀ ratios suggested thresholds of binding/uptake ratios above which compounds were likely to be substrates. Based on their potencies at hDAT, most of these compounds have potential for abuse and addiction. 4-Bromomethcathinone, 4-MEC, 5-methoxy-methylone, ethylone, and MDAI, which have higher potencies at hSERT than hDAT, may have empathogen psychoactivity.

Phase I metabolites of mephedrone display biological activity as substrates at monoamine transporters

BACKGROUND AND PURPOSE

4-Methyl-N-methylcathinone (mephedrone) is a synthetic stimulant that acts as a substrate-type releaser at transporters for dopamine (DAT), noradrenaline (NET) and 5-HT (SERT). Upon systemic administration, mephedrone is metabolized to several phase I compounds: the N-demethylated metabolite, 4-methylcathinone (nor-mephedrone); the ring-hydroxylated metabolite, 4-hydroxytolylmephedrone (4-OH-mephedrone); and the reduced keto-metabolite, dihydromephedrone.

EXPERIMENTAL APPROACH

We used in vitro assays to compare the effects of mephedrone and synthetically prepared metabolites on transporter-mediated uptake and release in HEK293 cells expressing human monoamine transporters and in rat brain synaptosomes. In vivo microdialysis was employed to examine the effects of i.v. metabolite injection (1 and 3 mg·kg(-1) ) on extracellular dopamine and 5-HT levels in rat nucleus accumbens.

KEY RESULTS

In cells expressing transporters, mephedrone and its metabolites inhibited uptake, although dihydromephedrone was weak overall. In cells and synaptosomes, nor-mephedrone and 4-OH-mephedrone served as transportable substrates, inducing release via monoamine transporters. When administered to rats, mephedrone and nor-mephedrone produced elevations in extracellular dopamine and 5-HT, whereas 4-OH-mephedrone did not. Mephedrone and nor-mephedrone, but not 4-OH-mephedrone, induced locomotor activity.

CONCLUSIONS AND IMPLICATIONS

Our results demonstrate that phase I metabolites of mephedrone are transporter substrates (i.e. releasers) at DAT, NET and SERT, but dihydromephedrone is weak in this regard. When administered in vivo, nor-mephedrone increases extracellular dopamine and 5-HT in the brain whereas 4-OH-mephedrone does not, suggesting the latter metabolite does not penetrate the blood-brain barrier. Future studies should examine the pharmacokinetics of nor-mephedrone to determine its possible contribution to the in vivo effects produced by mephedrone.