Mephedrone (4-methylmethcathinone; 'meow meow'): chemical, pharmacological and clinical issues

α-Pyrrolidinohexanophenone (α-PHP) and α-Pyrrolidinoisohexanophenone (α-PiHP): A Review

New Psychoactive Substances are currently a serious and growing problem affecting public health worldwide. By 2022, 1184 of these substances had been identified over a period of 16 years. Within these, α-pyrrolidinohexanophenone (α-PHP) and α-pyrrolidinoisohexanophenone (α-PiHP) have emerged, two synthetic cathinones from the pyrovalerone derivates subgroup that are positional isomers of each other. Alpha-PHP appeared on the Japanese illicit drug market in 2014 and, two years later, α-PiHP was identified for the first time in China. They were placed in schedule II on the list of Psychotropic Substances under International Control in 2020 and in March 2023, respectively. Both cathinones have no therapeutic potential for medical use and therefore are abused for recreational habits, which can lead to fatalities. The most frequent adverse effects reported are cardiac, psychiatric, and neurologic, and fatal intoxications have already been described. In Portugal, their consumption and consequent seizures are more prevalent on the archipelagos, which has been aggravating the health situation. In conclusion, these types of substances are a challenge for forensic toxicology since they are easily synthesized, modified, and placed on the market. Therefore, more studies to develop analytical methods to detect them and more comprehensive legislation should be applied. Thus, this review aimed to address the legislative, physicochemical, toxicological, and analytical aspects of both substances.

Mephedrone induces partial release at human dopamine transporters but full release at human serotonin transporters

Mephedrone (4-methylmethcathinone) is a cathinone derivative that is recreationally consumed for its energizing and empathogenic effects. The stimulating properties are believed to arise from the ability of mephedrone to interact with the high-affinity transporters for dopamine (DA) (DAT) and norepinephrine (NET), whereas the entactogenic effect presumably relies on its activity at the serotonin (5-HT) transporter (SERT). Early studies found that mephedrone acts as a releaser at NET, DAT and SERT, and thus promotes efflux of the respective monoamines. Evidence linked drug-induced reverse transport of 5-HT via SERT to prosocial effects, whereas activity at DAT is strongly correlated with abuse liability. Consequently, we sought to evaluate the pharmacology of mephedrone at human (h) DAT and SERT, heterologously expressed in human embryonic kidney 293 cells, in further detail. In line with previous studies, we report that mephedrone evokes carrier-mediated release via hDAT and hSERT. We found this effect to be sensitive to the protein kinase C inhibitor GF109203X. Electrophysiological recordings revealed that mephedrone is actively transported by hDAT and hSERT. However, mephedrone acts as a full substrate of hSERT but as a partial substrate of hDAT. Furthermore, when compared to fully efficacious releasing agents at hDAT and hSERT (i.e. S(+)-amphetamine and para-chloroamphetamine, respectively) mephedrone displays greater efficacy as a releaser at hSERT than at hDAT. In summary, this study provides additional insights into the molecular mechanism of action of mephedrone at hDAT and hSERT.

Stimulant and hallucinogenic novel psychoactive substances; an update

INTRODUCTION

The renewed interest in considering a range of stimulants, psychedelics and dissociatives as therapeutics emphasizes the need to draft an updated overview of these drugs' clinical and pharmacological issues.

AREAS COVERED

The focus here was on: stimulants (e.g. amphetamines, methamphetamine, and pseudoephedrine; phenethylamines; synthetic cathinones; benzofurans; piperazines; aminoindanes; aminorex derivatives; phenmetrazine derivatives; phenidates); classical (e.g. ergolines; tryptamines; psychedelic phenethylamines), and atypical (e.g. PCP/ketamine-like dissociatives) psychedelics.Stimulant and psychedelics are associated with: a) increased central DA levels (psychedelic phenethylamines, synthetic cathinones and stimulants); b) 5-HT receptor subtypes' activation (psychedelic phenethylamines; recent tryptamine and lysergamide derivatives); and c) antagonist activity at NMDA receptors, (phencyclidine-like dissociatives).

EXPERT OPINION

Clinicians should be regularly informed about the range of NPS and their medical, psychobiological and psychopathological risks both in the acute and long term. Future research should focus on an integrative model in which pro-drug websites' analyses are combined with advanced research approaches, including computational chemistry studies so that in vitro and in vivo preclinical studies of index novel psychoactives can be organized. The future of psychedelic research should focus on identifying robust study designs to convincingly assess the potential therapeutic benefits of psychedelics, molecules likely to present with limited dependence liability levels.

Electrochemical detection of mephedrone using a graphene screen-printed electrode: a new sensitive and selective approach to identify synthetic cathinones in forensic analysis

Mephedrone (MEP) is an illicit stimulant drug that belongs to the synthetic cathinone (SC) class, which has been widely used for recreational purposes and reported in forensic analysis. The preliminary identification of MEP and other SCs in seized samples is of great interest for forensic investigation and a fast and simple screening test for these drugs would be useful for on-site and in-house analyses. In this study, we present the electrochemical detection of MEP in forensic samples using, for the first time, independent redox processes of SCs on a graphene screen-printed electrode (SPE-GP). The proposed method for MEP detection on the SPE-GP was optimized in Britton-Robinson buffer solution (0.1 mol L^-1) at pH 10.0 with adsorptive stripping differential pulse voltammetry (AdSDPV). The use of the SPE-GP with AdSDPV provides a wide linear range for MEP determination (2.6 to 112 μmol L^-1) with a low limit of detection (LOD) (0.3 μmol L^-1). The real surface area available for adsorption on the SPE-GP was estimated to be between 3.80 and 5.70 cm², which provided high sensitivity for the proposed method. Furthermore, good stability of MEP electrochemical responses on the SPE-GP was obtained using the same or different electrodes (N = 3), with relative standard deviation (RSD) < 5.0% for both redox processes. Interference studies for a common adulterant (caffeine) and twelve other illicit drugs (phenethylamines, amphetamines, and other SCs) were performed with a highly selective response for MEP detection. Therefore, the SPE-GP with AdSDPV is demonstrated to be a selective and sensitive screening method to detect MEP and other SCs in forensic analysis, providing a fast and simple preliminary identification of these drugs in seized samples.

Toxicological Analysis of Cases of Mixed Poisonings with Synthetic Cathinones and Other Drugs of Abuse

Some of the most commonly used new psychoactive substances (NPSs) are synthetic cathinones (SCs). The literature increasingly indicates that SCs have a significant addictive potential and pose a high risk to human health and life. The vast majority of SC users take a number of substances simultaneously. This article lists the detected concentrations in 26 fatal and 2 non-fatal real cases, in which SCs or an SC along with other substances were determined in blood and other biological materials. The following SCs were found most often: α-pyrrolidinohexiophenone, α-pyrrolidinopentiophenone, N-ethylpentedrone (NEP), 4-methyl-α-ethylaminopentiophenone and N-ethylhexedrone. In addition to detected SCs, the analyzed samples showed the presence of conventional drugs such as methamphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine, amphetamine and NPSs from groups other than SCs, such as synthetic cannabinoids (UR-144 and 5F-AMB), synthetic opioids (AH-7921, U-47700 and 4-fluorobutyrfentanyl) and others (desoxypipradrol and etizolam). The quantitative analyses were carried out by liquid chromatography with tandem mass spectrometry (LC-MS-MS). This study presents pioneering data on concentrations and effects of 4-ethylmethcathinone, NEP, N-ethylbuphedrone and mexedrone. Also noteworthy are the data on SCs that until now have rarely been described in the literature together with specified blood concentrations. The analyzed cases of taking SCs were associated with fatal intoxication (n = 26), driving under the influence of drugs (n = 2) and death caused by beating (n = 1). Taking SCs has serious side effects that can lead to multiple organ failure and death. The use of more than one psychoactive substance simultaneously (including at least one SC) contributes to increased SC toxicity. These data could be valuable for further interpretation of other results from toxicological analyses.

Behavioral and Pharmacokinetics Studies of N-Methyl-2-Aminoindane (NM2AI) in Mice: An Aminoindane Briefly Used in the Illicit Drug Market

Drug forums are considered as the main platform sources that have contributed to the increase in NPS popularity, especially for those not yet known to law enforcement and therefore not yet illegal. An example is the new synthetic stimulant NM2AI, which has a very short history of human use and abuse. Little is known regarding this compound, but some information from internet forums and the scientific literature indicates NM2AI as a structural derivate of MDAI, which is known for its entactogenic activity. Indeed, the purpose of this study is to evaluate, for the first time, the in vivo acute effect induced by the intraperitoneal injection of NM2AI (1-10-30-100 mg/kg) in mice. We demonstrate the sensory (by visual placing and object tests) and physiological (core temperature measurement) function variations, nociceptor (by tail pinch test) and strength (grip test) alterations, and sensorimotor (time on rod and mobility) decrease. Moreover, we verify the mild hallucinogenic effect of NM2AI (by startle/prepulse inhibition test). Lastly, we perform a pharmacokinetic study on mice blood samples, highlighting that the main active metabolite of NM2AI is 2-aminoindane (2AI). Taken together, our data confirm the suspected entactogenic activity of NM2AI; however, these in vivo effects appear atypical and less intense with respect to those induced by the classic stimulants, in surprising analogy with what is reported by networked users.

Binge-like mephedrone treatment induces memory impairment concomitant with brain kynurenic acid reduction in mice

While mephedrone (4-methylmethcathinone), a synthetic cathinone derivative, is widely abused by adolescents and young adults, the knowledge about its long-term effects on memory processes is limited. Kynurenic acid (KYNA) is a neuroactive metabolite of the kynurenine pathway of tryptophan degradation. KYNA is considered an important endogenous modulator influencing physiological and pathological processes, including learning and memory processes. The aim of this study was to determine whether (A) binge-like mephedrone administration (10.0 and 30.0 mg/kg, intraperitoneally, in 4 doses separated by 2 h) induces memory impairments, assessed 2, 8 and 15 days after mephedrone cessation in the passive avoidance test in mice, and whether (B) KYNA is involved in these memory processes. To clarify the role of KYNA in the mephedrone effects, its level in the murine brain in vivo, and in cortical slices in vitro, as well as the activities of kynurenine aminotransferases (KATs) I and II were assessed. Furthermore, cell line experiments were conducted to investigate the effects of mephedrone on normal human brain cells. Our results showed memory impairments 8 and 15 days after binge-like mephedrone administration. At the same time, reduction in the KYNA level in the murine brain was noted. In vitro studies showed no effect of mephedrone on the production of KYNA in cortical slices or on the activity of the KAT I and II enzymes. Finally, exposure of normal cells to mephedrone in vitro resulted in a modest reduction of cell viability and proliferation.

Development of an Electrochemical Sensor Using a Modified Carbon Paste Electrode with Silver Nanoparticles Capped with Saffron for Monitoring Mephedrone

Mephedrone, also known as 4-methylmethcathinone, is growing into a prominent recreational drug for young people. When it came to detecting mephedrone, limited efforts were made using electrochemical sensors. As a result, this application depicts the fabrication of a new, sensitive, selective, and economical electrochemical sensor capable of detecting mephedrone by using silver nanoparticles capped with saffron produced through electropolymerization to modify carbon paste electrodes (CPEs). Silver nanoparticles (AgNPs) were capped with saffron (AgNPs@Sa) using a green method. AgNPs@Sa were studied using electron scanning microscopy (SEM) and UV-vis spectroscopy. The sensor was evaluated under the optimum condition to determine its analytical features. The results showed that this procedure had a wide linear range, low detection limit and sufficient reproducibility. Furthermore, the sensor posed sufficient stability. Moreover, it was applied in the determination of mephedrone in urine samples, showing the potential applicability of this electrochemical sensor in real sample analysis.

Alteration of Ethanol Reward by Prior Mephedrone Exposure: The Role of Age and Matrix Metalloproteinase-9 (MMP-9)

Mephedrone, a synthetic cathinone, is widely abused by adolescents and young adults. The aim of this study was to determine: (i) whether prior mephedrone exposure would alter ethanol reward and (ii) whether age and matrix metalloproteinase-9 (MMP-9) are important in this regard. In our research, male Wistar rats at postnatal day 30 (PND30) received mephedrone at the dose of 10 mg/kg, i.p., 3 times a day for 7 days. To clarify the role of MMP-9 in the mephedrone effects, one mephedrone-treated group received minocycline, as an MMP-9 antagonist. Animals were then assigned to conditioned place preference (CPP) procedure at PND38 (adolescent) or at PND69 (adult). After the CPP test (PND48/79), expression of dopamine D1 receptors (D1R), Cav1.2 (a subtype of L-type calcium channels), and MMP-9 was quantified in the rat ventral striatum (vSTR). The influence of mephedrone administration on the N-methyl-D-aspartate glutamate receptors (NMDAR) subunits (GluN1, GluN2A, and GluN2B) was then assessed in the vSTR of adult rats (only). These results indicate that, in contrast with adolescent rats, adult rats with prior mephedrone administration appear to be more sensitive to the ethanol effect in the CPP test under the drug-free state. The mephedrone effect in adult rats was associated with upregulation of D1R, NMDAR/GluN2B, MMP-9, and Cav1.2 signaling. MMP-9 appears to contribute to these changes in proteins expression because minocycline pretreatment blocked mephedrone-evoked sensitivity to ethanol reward. Thus, our results suggest that prior mephedrone exposure differentially alters ethanol reward in adolescent and adult rats.

Central Effects of the Designer Drug Mephedrone in Mice—Basic Studies

Mephedrone belongs to the “party drugs” thanks to its psychostimulant effects, similar to the ones observed after amphetamines. Though mephedrone is used worldwide by humans and in laboratory animals, not all properties of this drug have been discovered yet. Therefore, the main aim of this study was to expand the knowledge about mephedrone’s activity in living organisms. A set of behavioral tests (i.e., measurement of the spontaneous locomotor activity, rotarod, chimney, elevated plus maze with its modification, novel object recognition, and pentylenetetrazol seizure tests) were carried out in male albino Swiss mice. Different dose ranges of mephedrone (0.05–5 mg/kg) were administered. We demonstrated that mephedrone at a dose of 5 mg/kg rapidly increased the spontaneous locomotor activity of the tested mice and its repeated administration led to the development of tolerance to these effects. Mephedrone showed the anxiolytic-like potential and improved spatial memory, but it did not affect recognition memory. Moreover, the drug seemed not to have any anticonvulsant or proconvulsant activity. In conclusion, mephedrone induces many central effects. It easily crosses the blood-brain barrier and peaks in the brain quickly after exposure. Our experiment on inducing a hyperlocomotion effect showed that mephedrone‘s effects are transient and lasted for a relatively short time.

Drugs of Abuse: Sympathomimetics

Sympathomimetic drugs comprise a broad category of substances including both illicit and prescribed drugs that have deleterious effects when ingested or abused. The clinical syndromes that result from overstimulation of the sympathetic nervous system by reuptake inhibition of biogenic amines, such as norepinephrine and dopamine, carry significant morbidity. Recognition and awareness of the appropriate supportive measures are required to mitigate life-threatening complications of multiple organ systems. The sympathomimetic toxidrome is recognized by a constellation of symptoms including agitation, hyperthermia, tachycardia, and hypertension, and the primary treatment involves supportive care, including the liberal use of benzodiazepines.

Pharmacokinetics of Mephedrone and Its Metabolites in Whole Blood and Plasma after Controlled Intranasal Administration to Healthy Human Volunteers

Mephedrone is a popular synthetic cathinone, known for its psychostimulant effects. At present, there is no data available on the pharmacokinetics of mephedrone and its metabolites in concurrently collected whole blood and plasma samples after a controlled intranasal administration to healthy volunteers. In this study, six healthy male volunteers nasally insufflated 100 mg of pure mephedrone hydrochloride (Day 1). Whole blood and plasma samples were collected at different time points after the administration and were analyzed for the presence of mephedrone and its metabolites, dihydro-mephedrone (DHM), nor-mephedrone (NOR), hydroxytolyl-mephedrone (HYDROXY), 4-carboxy-mephedrone (4-CARBOXY) and dihydro-nor-mephedrone (DHNM), by validated liquid chromatography-tandem mass spectrometry methods. All analytes were detected in whole blood and plasma for 6 h post administration, with mephedrone and NOR also being detectable on Day 2 in some participants. 4-CARBOXY, followed by NOR, was the most abundant metabolite in both matrices. Compared to other psychostimulants, mephedrone showed rapid absorption (mean Tmax of 52.5 ± 20.7 min in plasma and 55.0 ± 18.2 min in whole blood) and elimination (mean t1/2 of 1.98 ± 0.30 h in plasma and 2.12 ± 0.33 h in whole blood). In addition, statistical analysis showed that median whole blood to plasma distribution ratios, reported here for the first time, were statistically different from 1 (unity) for mephedrone (median: 1.11), DHM (median: 1.30) and NOR (median: 0.765). It is hoped that the study will aid forensic and clinical toxicologists in detection, identification and interpretation of cases associated with mephedrone use.

Human Neuronal Cell Lines as An In Vitro Toxicological Tool for the Evaluation of Novel Psychoactive Substances

Novel psychoactive substances (NPS) are synthetic substances belonging to diverse groups, designed to mimic the effects of scheduled drugs, resulting in altered toxicity and potency. Up to now, information available on the pharmacology and toxicology of these new substances is very limited, posing a considerable challenge for prevention and treatment. The present in vitro study investigated the possible mechanisms of toxicity of two emerging NPS (i) 4′-methyl-alpha-pyrrolidinoexanophenone (3,4-MDPHP), a synthetic cathinone, and (ii) 2-chloro-4,5-methylenedioxymethamphetamine (2-Cl-4,5-MDMA), a phenethylamine. In addition, to apply our model to the class of synthetic opioids, we evaluated the toxicity of fentanyl, as a reference compound for this group of frequently abused substances. To this aim, the in vitro toxic effects of these three compounds were evaluated in dopaminergic-differentiated SH-SY5Y cells. Following 24 h of exposure, all compounds induced a loss of viability, and oxidative stress in a concentration-dependent manner. 2-Cl-4,5-MDMA activates apoptotic processes, while 3,4-MDPHP elicits cell death by necrosis. Fentanyl triggers cell death through both mechanisms. Increased expression levels of pro-apoptotic Bax and caspase 3 activity were observed following 2-Cl-4,5-MDMA and fentanyl, but not 3,4-MDPHP exposure, confirming the different modes of cell death.

An updated review on synthetic cathinones

Cathinone, the main psychoactive compound found in the plant Catha edulis Forsk. (khat), is a β-keto analogue of amphetamine, sharing not only the phenethylamine structure, but also the amphetamine-like stimulant effects. Synthetic cathinones are derivatives of the naturally occurring cathinone that largely entered the recreational drug market at the end of 2000s. The former "legal status", impressive marketing strategies and their commercial availability, either in the so-called "smartshops" or via the Internet, prompted their large spread, contributing to their increasing popularity in the following years. As their popularity increased, the risks posed for public health became clear, with several reports of intoxications and deaths involving these substances appearing both in the social media and scientific literature. The regulatory measures introduced thereafter to halt these trending drugs of abuse have proved to be of low impact, as a continuous emergence of new non-controlled derivatives keep appearing to replace those prohibited. Users resort to synthetic cathinones due to their psychostimulant properties but are often unaware of the dangers they may incur when using these substances. Therefore, studies aimed at unveiling the pharmacological and toxicological properties of these substances are imperative, as they will provide increased expertise to the clinicians that face this problem on a daily basis. The present work provides a comprehensive review on history and legal status, chemistry, pharmacokinetics, pharmacodynamics, adverse effects and lethality in humans, as well as on the current knowledge of the neurotoxic mechanisms of synthetic cathinones.

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.

Effects of Mephedrone and Amphetamine Exposure during Adolescence on Spatial Memory in Adulthood: Behavioral and Neurochemical Analysis

A synthetic cathinone, mephedrone is widely abused by adolescents and young adults. Despite its widespread use, little is known regarding its long-term effects on cognitive function. Therefore, we assessed, for the first time, whether (A) repeated mephedrone (30 mg/kg, i.p., 10 days, once a day) exposure during adolescence (PND 40) induces deleterious effects on spatial memory and reversal learning (Barnes maze task) in adult (PND 71-84) rats and whether (B) these effects were comparable to amphetamine (2.5 mg/kg, i.p.). Furthermore, the influence of these drugs on MMP-9, NMDA receptor subunits (GluN1, GluN2A/2B) and PSD-95 protein expression were assessed in adult rats. The drug effects were evaluated at doses that per se induce rewarding/reinforcing effects in rats. Our results showed deficits in spatial memory (delayed effect of amphetamine) and reversal learning in adult rats that received mephedrone/amphetamine in adolescence. However, the reversal learning impairment may actually have been due to spatial learning rather than cognitive flexibility impairments. Furthermore, mephedrone, but not amphetamine, enhanced with delayed onset, MMP-9 levels in the prefrontal cortex and the hippocampus. Mephedrone given during adolescence induced changes in MMP-9 level and up-regulation of the GluN2B-containing NMDA receptor (prefrontal cortex and hippocampus) in young adult (PND 63) and adult (PND 87) rats. Finally, in adult rats, PSD-95 expression was increased in the prefrontal cortex and decreased in the hippocampus. In contrast, in adult rats exposed to amphetamine in adolescence, GluN2A subunit and PSD-95 expression were decreased (down-regulated) in the hippocampus. Thus, in mephedrone-but not amphetamine-treated rats, the deleterious effects on spatial memory were associated with changes in MMP-9 level. Because the GluN2B-containing NMDA receptor dominates in adolescence, mephedrone seems to induce more harmful effects on cognition than amphetamine does during this period of life.

Identification of Unique 4-Methylmethcathinone (4-MMC) Degradation Markers in Putrefied Matrices†

Drug degradation as a consequence of putrefactive bacterial activity is a well-known factor that affects the identification and quantitation of certain substances of forensic interest. Current knowledge on putrefaction-mediated degradation of drugs is, however, significantly lacking. This study aimed to investigate the degradation of 4-methylmethcathinone (4-MMC or mephedrone) and to detect its degradation products in putrefied biological matrices containing 4-MMC. The bacteria species Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris were grown in brain-heart infusion broth, spiked with 4-MMC and incubated at 37°C for 24 h. Postmortem human blood and fresh porcine liver macerate were also left to putrefy in sample tubes at room temperature for 1 week. Structural elucidation was based on modern spectroscopic analyses including the use of high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. All four putrefactive bacteria were capable of degrading 4-MMC extensively under the experimental conditions explored. Of particular interest was the discovery of a novel degradation product common to all four bacterial species, which was assigned as 2-hydroxy-1-(4-methylphenyl)propan-1-one (HMP) based on the spectroscopic data. This degradation product was detectable in both postmortem human blood and porcine liver samples. The stability of the identified degradation products, especially HMP, should be further investigated to assess their validity of serving as marker analytes for monitoring 4-MMC in postmortem toxicology.

Recent bionalytical methods for the determination of new psychoactive substances in biological specimens

One of the problems associated with the consumption of new psychoactive substances is that in most scenarios of acute toxicity the possibility of quick clinical action may be impaired because many screening methods are not responsive to them, and laboratories are not able to keep pace with the appearance of new substances. For these reasons, developing and validating new analytical methods is mandatory in order to efficiently face those problems, allowing laboratories to be one step ahead. The goal of this work is to perform a critical review regarding bionalytical methods that can be used for the determination of new psychoactive substances (phenylethylamines, cathinones, synthetic cannabinoids, opioids, benzodiazepines, etc), particularly concerning sample preparation techniques and associated analytical methods.

Comparative Untargeted Metabolomics Analysis of the Psychostimulants 3,4-Methylenedioxy-Methamphetamine (MDMA), Amphetamine, and the Novel Psychoactive Substance Mephedrone after Controlled Drug Administration to Humans

Psychoactive stimulants are a popular drug class which are used recreationally. Over the last decade, large numbers of new psychoactive substances (NPS) have entered the drug market and these pose a worldwide problem to human health. Metabolomics approaches are useful tools for simultaneous detection of endogenous metabolites affected by drug use. They allow identification of pathways or characteristic metabolites, which might support the understanding of pharmacological actions or act as indirect biomarkers of consumption behavior or analytical detectability. Herein, we performed a comparative metabolic profiling of three psychoactive stimulant drugs 3,4-methylenedioxymethamphetamine (MDMA), amphetamine and the NPS mephedrone by liquid chromatography-high resolution mass spectrometry (LC-HRMS) in order to identify common pathways or compounds. Plasma samples were obtained from controlled administration studies to humans. Various metabolites were identified as increased or decreased based on drug intake, mainly belonging to energy metabolism, steroid biosynthesis and amino acids. Linoleic acid and pregnenolone-sulfate changed similarly in response to intake of all drugs. Overall, mephedrone produced a profile more similar to that of amphetamine than MDMA in terms of affected energy metabolism. These data can provide the basis for further in-depth targeted metabolome studies on pharmacological actions and search for biomarkers of drug use.

Enantioseparation and Determination of Mephedrone and Its Metabolites by Capillary Electrophoresis Using Cyclodextrins as Chiral Selectors

Mephedrone, a psychoactive compound derived from cathinone, is widely used as a designer drug. The determination of mephedrone and its metabolites is important for understanding its possible use in medicine. In this work, a method of capillary electrophoresis for the chiral separation of mephedrone and its metabolites was developed. Carboxymethylated β-cyclodextrin was selected as the most effective chiral selector from seven tested cyclodextrin derivates. Based on the simplex method, the optimal composition of the background electrolyte was determined: at pH 2.75 and 7.5 mmol·L^-1 carboxymethylated β-cyclodextrin the highest total resolution of a mixture of analytes was achieved. For mephedrone and its metabolites, calibration curves were constructed in a calibration range from 0.2 to 5 mmol·L^-1; limits of detection, limits of quantification, precision, and repeatability were calculated, and according to Mandel's fitting test, the linear calibration ranges were determined.

The rise of new psychoactive substances and psychiatric implications: A wide-ranging, multifaceted challenge that needs far-reaching common legislative strategies

The ever-growing number of novel psychoactive substances (NPS) that have been surfacing globally, as well as related changes in drug abuse trends, undoubtedly constitute a difficult and multifaceted challenge for psychiatry. The intake and abuse of such substances has been linked to a risk of psychopathological disturbances, which stem from imbalances of a range of neurotransmitter pathways and receptors. Through an analysis of relevant research articles and reviews (particularly those outlining NPS neurological and cerebral mechanisms of action and psychopathological consequences arising from NPS abuse; research papers more closely focused on chemical/pharmacological aspects have been ruled out), through a systematic analysis of Pubmed, Medline, PsycLIT and EMBASE literature, as well as data released by health care institutions and drug enforcement agencies (among which the World Health Organization, the United Nations Office on Drugs and Crime, the European Monitoring Centre for Drugs and Drug Addiction, Eurojust, the Novel Psychoactive Treatment UK Network, the Court of Justice of the European Union), the authors aimed to elaborate on the most relevant data relative to NPS-related psychiatric effects, focusing on the conceptual and definition-related complexities inherent to NPS, clinical management and motivations for NPS use; moreover, an effort has been made to highlight the possible measures in order to tackle the unremitting rise of such elusive and potentially harmful substances.

Locomotor sensitization in male Sprague-Dawley rats following repeated concurrent treatment with 4-methylmethcathinone and 3,4-methylenedioxymethamphetamine

Recreational abuse of illicit synthetic cathinones is an ongoing public health concern. Recent studies indicate that the methcathinone derivative 4-methylmethcathinone (4-MMC) produces behavioral and neurochemical effects similar to the entactogen 3,4-methylenedioxymethamphetamine (MDMA). Whereas polysubstance abuse is common, most preclinical studies of drug abuse liability only evaluate the effects of single drugs. Utilizing the locomotor sensitization paradigm, the present study assessed the combined locomotor stimulant effects of 4-MMC and MDMA for induction of sensitization following repeated administration and for expression of sensitization to a challenge dose of either substance alone after a 10-day period of drug abstinence. Male Sprague-Dawley rats received once daily intraperitoneal injections of saline, 4-MMC (1.0 mg/kg or 5.0 mg/kg), MDMA (3.0 mg/kg), or a mixture containing 4-MMC (1.0 mg/kg or 5.0 mg/kg) + MDMA (3.0 mg/kg) for 7 consecutive days. Following a 10-day drug-free period, rats were given a single intraperitoneal injection of either saline, 4-MMC (1.0 or 5.0 mg/kg), or 3.0 mg/kg MDMA. Activity was recorded for 1 h immediately before and 1 h immediately after injections on days 1, 7, and 17. 4-MMC treatment failed to induce locomotor sensitization, but, when combined with MDMA, sensitization was induced to a greater extent than with MDMA alone. Furthermore, the expression of sensitization to a subsequent challenge dose of MDMA was observed only in animals previously exposed to MDMA or a 5.0 mg/kg 4-MMC + MDMA mixture. In consideration of these findings along with the fact that 4-MMC has similar neurochemical actions to MDMA, further research may be warranted to determine the abuse liability of drug mixtures including 4-MMC and MDMA.

Toxicological profile and structure–activity relationship of new synthetic cathinones

According to the Chief Sanitary Inspectorate, 75% of the compounds identified as new psychoactive substances in Poland are represented by synthetic cathinones. The aim of the presented paper is to describe the pharmacological profile of synthetic cathinones, including the structure-activity relationship and its impact on their biological effects. This article also includes a review of the literature on fatal and non-fatal intoxication cases associated with the administration of well-described synthetic cathinones, as well as their new derivatives. This review also characterises the influence of the amendment to the Act of August 2018 concerning the prevention of drug abuse on the process of banning new drugs and the current legal situation related to the abuse of new psychoactive substances.

Mephedrone and MDMA: A comparative review

Mephedrone and MDMA are both constituents of party drugs, with mephedrone being relatively new compared to MDMA. This review compares current knowledge regarding the patterns of usage and neuropsychobiological effects of both mephedrone and MDMA. Both drugs share common psychoactive effects, the duration of which is significantly shorter with mephedrone use, attributing towards a pattern of binge use among users. Both drugs have also been associated with adverse health, psychiatric, and neurocognitive problems. Whilst there is extensive research into the psychobiological problems induced by MDMA, the evidence for mephedrone is comparatively limited. The adverse effect profile of mephedrone appears to be less severe than that of MDMA. Users often believe it to be safer, although both drugs have been associated with overdoses. The neurotoxic potential of mephedrone appears to be low, whereas MDMA can cause long-term damage to the serotonergic system, although this needs further investigation. The abuse liability of mephedrone is significantly greater than that of MDMA, raising concerns regarding the impact of lifetime usage on users. Given that mephedrone is relatively new, the effects of long-term exposure are yet to be documented. Future research focused on lifetime users may highlight more severe neuropsychobiological effects from the drug.

The clinical challenges of synthetic cathinones

AIMS

Within the new psychoactive substances (NPS) scenario, several hundred different molecules, mostly including synthetic cannabinoids and cathinones, have been identified so far. The aims of the paper were to: (i) identify the number of synthetic cathinones mentioned in a range of psychonaut, NPS-related, online sources; and (ii) describe the associated acute/long term clinical scenario and the related treatment/management plan.

METHODS

After about 18 months of operation and exclusion of false positives/duplicates, some 4204 unique NPS molecules were included in the NPSfinder® crawling/navigating software database. Most popular NPS included: 1265 psychedelic phenethylamines (30.1%; confidence interval [CI] 95%: 28.7-31.5%); 1253 synthetic cannabinoids (29.8%; CI 95%: 28.4-31.2%); 429 synthetic opioids (10.2%; CI 95%: 9.3-10.2%); and 171 synthetic cathinones (4.1%; CI 95% 3.5-4.7%). Conversely, the United Nations Office on Drugs and Crime and the European Monitoring Centre for Drugs and Drug Addiction databases respectively included 169 and 140 cathinones. Overall, the 3 databases reported some 222 synthetic cathinones, and 41 were uniquely identified by the NPSfinder®.

RESULTS

In terms of clinical scenarios, synthetic cathinone ingestion is initially associated with stimulant effects; however, psychopathological disturbances, violence, suicidal behaviour, hyperthermia, coma and death have also been described.

CONCLUSION

The proportion of cathinones commented on by psychonaut fora appeared to be relatively small, and similar to those reported by both the United Nations Office on Drugs and Crime and European Monitoring Centre for Drugs and Drug Addiction. This may be associated with a recent significant decline in both cathinone-related consumption and acute medical presentation. Due to their complex behavioural and medical toxicity issues, healthcare professionals should be, however, be educated to recognise the signs and symptoms of NPS, including synthetic cathinone, ingestion.

Mephedrone and Alcohol Interactions in Humans

Mephedrone (4-MMC, mephedrone) is a synthetic cathinone derivative included in the class of new psychoactive substances. It is commonly used simultaneously with alcohol (ethanol). The aim of the present study was to evaluate the interactions on subjective, cardiovascular and hormone effects and pharmacokinetics between mephedrone and alcohol in humans. Eleven male volunteers participated as outpatients in four experimental sessions in a double-blind, randomized, cross-over, and placebo-controlled clinical trial. Participants received a single oral dose of 200 mg of mephedrone plus 0.8 g/kg of alcohol (combination condition); 200 mg of mephedrone plus placebo alcohol (mephedrone condition); placebo mephedrone plus 0.8 g/kg of ethanol (alcohol condition); and placebo mephedrone plus placebo alcohol (placebo condition). Outcome variables included physiological (blood pressure, heart rate, temperature, and pupil diameter), psychomotor (Maddox wing), subjective (visual analogue scales, Addiction Research Center Inventory 49 item short form, and Valoración de los Efectos Subjetivos de Sustancias con Potencial de Abuso questionnaire), and pharmacokinetic parameters (mephedrone and ethanol concentrations). The study was registered in ClinicalTrials.gov, number NCT02294266. The mephedrone and alcohol combination produced an increase in the cardiovascular effects of mephedrone and induced a more intense feeling of euphoria and well-being in comparison to the two drugs alone. Mephedrone reduced the sedative effects produced by alcohol. These results are similar to those obtained when other psychostimulants such as amphetamines and 3,4-methylenedioxymethamphetamine are combined simultaneously with alcohol. The abuse liability of mephedrone combined with alcohol is greater than that induced by mephedrone alone.

Of mice and men on MDMA: A translational comparison of the neuropsychobiological effects of 3,4-methylenedioxymethamphetamine ('Ecstasy')

MDMA (3,4-methylendioxymethamphetamine), also known as Ecstasy, is a stimulant drug recreationally used by young adults usually in dance clubs and raves. Acute MDMA administration increases serotonin, dopamine and noradrenaline by reversing the action of the monoamine transporters. In this work, we review the studies carried out over the last 30 years on the neuropsychobiological effects of MDMA in humans and mice and summarise the current knowledge. The two species differ with respect to the neurochemical consequences of chronic MDMA, since it preferentially induces serotonergic dysfunction in humans and dopaminergic neurotoxicity in mice. However, MDMA alters brain structure and function and induces hormonal, psychomotor, neurocognitive, psychosocial and psychiatric outcomes in both species, as well as physically damaging and teratogen effects. Pharmacological and genetic studies in mice have increased our knowledge of the neurochemical substrate of the multiple effects of MDMA. Future work in this area may contribute to developing pharmacological treatments for MDMA-related disorders.

The Psychiatric Characteristics of People on a Mephedrone ("bath salts") Binge

Background: Despite solutions presented by the European Union and national regulations introduced by many countries, the problem of mephedrone (4-MMC) is growing. Objectives: The aim of this study was to investigate the effect of regular mephedrone intake with other psychoactive substances on the clinical picture of patients, including self-harms and suicide attempts. Methods: The study involved a group of 601 patients addicted to mephedrone who were admitted to a psychiatric hospital between 2010 and 2018 due to regular mephedrone intake. Results: There was a statistically significant relationship between sleep disorders and mephedrone combined with alcohol (p < .05) or cannabinols (p < .05). However, the highest number of statistically significant correlations was reported when mephedrone was combined with opioids. There was a growing year-on-year percentage of people who attempted suicide because of regular mephedrone intake (p < .001). The more psychoactive substances were combined with mephedrone, the greater the risk of attempted suicide (p < .01). 20% of the examined group were hospitalized several times. Among those hospitalized several times, significantly more people took more than one additional psychoactive substance (p < .01). Conclusions: The more psychoactive substances combined with mephedrone, the more clinical symptoms are associated with it.

Detection of mephedrone and its metabolites in fingerprints from a controlled human administration study by liquid chromatography-tandem mass spectrometry and paper spray-mass spectrometry

Mephedrone and one of its metabolites have been detected for the first-time in fingerprints collected from a controlled human mephedrone administration study.

Synthetic cathinones: an evolving class of new psychoactive substances

Synthetic cathinones (SCat) are amphetamine-like psychostimulants that emerged onto drug markets as "legal" alternatives to illicit drugs such as ecstasy, cocaine, and amphetamines. Usually they are sold as "bath salts," "plant food," or "research chemicals," and rapidly gained popularity amongst drugs users due to their potency, low cost, and availability. In addition, internet drug sales have been replacing the old way of supplying drugs of abuse, contributing to their rapid spread. Despite the legislative efforts to control SCat, new derivatives continue to emerge on the recreational drugs market and their abuse still represents a serious public health issue. To date, about 150 SCat have been identified on the clandestine drugs market, which are one of the largest groups of new psychoactive substances (NPS) monitored by the United Nations Office on Drugs and Crime and the European Monitoring Center for Drugs and Drug Addiction. Similar to the classical stimulants, SCat affect the levels of catecholamines in the central nervous system, which results in their psychological, behavioral and toxic effects. Generally, the effects of SCat greatly differ from drug to drug and relatively little information is available about their pharmacology. The present work provides a review on the development of SCat as substances of abuse, current patterns of abuse and their legal status, chemical classification, known mechanisms of action, and their toxicological effects.

Mephedrone Impact on Matrix Metalloproteinases Activity - Do they Influence the Memory Processes?

BACKGROUND

The use of drugs of addiction, as mephedrone, is associated with functional neuronal disorders due to remodeling of the nervous tissue. Key enzymes in remodeling are extracellular matrix (ECM) proteases like matrix metalloproteases (MMPs). Recently, MMPs have been of great interest as some studies point to a fact that the alterations in structural remodeling of synaptic connections modify learning-dependent changes, which remain active even after a prolonged period of abstinence. This entails a continuous development of dependence.

OBJECTIVES

The aim of the study was to determine the influence of subchronic exposure to three different doses of mephedrone on the activity of MMP-2 and 9 in hippocampus and prefrontal cortex and how this was correlated with memory processes in mice.

METHODS

The homogenates of hippocampus and cortex were assayed for MMP-2 and MMP-9 activity by gelatin zymography. Memory consolidation processes were evaluated in the passive avoidance (PA) test.

RESULTS

The study confirmed the dose-dependent increase in activity of MMP-2 and -9 exerted by subchronic administration of mephedrone. Moreover, the highest dose of mephedrone attenuated consolidation of memory and learning processes.

CONCLUSIONS

We could hypothesize that inhibition of MMPs can be considered as a therapeutic option for the treatment of addictive behaviors associated with cognitive processes. Moreover, further studies are required to find out if elevated activities of MMPs contribute to brain damage or recovery from brain damage caused directly by mephedrone.

Evidence for public health on novel psychoactive substance use: a mixed-methods study

Background

Novel psychoactive substances (NPSs) contribute to the public health impact of substance misuse. This report provides research evidence addressing 11 research questions related to NPSs, covering types, patterns and settings of use; supply sources; and implications for policy and practice.

Methods

The study used a conceptually linked three-phase mixed-methods design with a shared conceptual framework based on multiple-context risk and protective factors. Phase 1 was a quantitative phase involving secondary data analysis of the longitudinal Belfast Youth Development Study (BYDS), a latent class analysis using the 2039 BYDS participants. Phase 2 was an extensive qualitative analysis via narrative interviews with participants, sampled from BYDS, drug/alcohol services and prisons, to explore NPS use trajectories. Phase 3 was the final quantitative phase; generalisability of the shared risk factor part of the model was tested using the manual three-step approach to examine risk factors associated with latent class membership. The quantitative and qualitative analyses were integrated, thus allowing emerging findings to be further explored.

Results

The data suggest that NPSs have a place within a range of polydrug use trajectories. Models showed no distinctive NPS class, with no clear evidence of differential risks for NPS use compared with the use of other substances. From the qualitative analysis, a taxonomy of groups was derived that explored how and where NPSs featured in a range of trajectories. This taxonomy was used to structure the analysis of factors linked to use within a risk and protective framework. Drivers for use were considered alongside knowledge, perceptions and experience of harms. Suggestions about how interventions could best respond to the various patterns of use – with special consideration of synthetic cannabinoids (SCs), including how they relate to the use of heroin and the potential for NPSs to operate as a ‘snare’ to more problem use – were also presented.

Limitations

The study was conducted during 2016/17; generalisability beyond this sample and time point is limited. The level of missing data for some of the BYDS analysis was a limitation, as was the fact that the BYDS data were collected in 2011, so in a different context from the data collected during the narrative interviews. The Psychoactive Substances Act 2016 (Great Britain. Psychoactive Substances Act 2016. London: The Stationery Office; 2016) came into force during qualitative fieldwork and, although not particularly influential in this study, may be influential in future work. It is acknowledged that many of the data related to SCs and mephedrone. Although drug use was measured by self-report, the strength of rapport within interviews, reflective diaries and methodological acceptability checks helped to mitigate self-report bias.

Conclusions

NPSs continue to present significant challenges for legislation and monitoring, researching and developing interventions. Understanding of usage patterns remains poor, with most information based on populations and settings where problems have already occurred. This research contributes to the evidence base by providing much needed further empirical data on the lived experiences of NPS users across a range of settings. In the light of these data, implications for policy and practice are discussed.

Future work

Future research must generate improved epidemiological data on the extent, patterns and motivations for use longitudinally. The uniqueness of the information concerning SC use points to a specific set of findings not evidenced in other literature (e.g. intensity of SC withdrawal). Future research should focus on the symbiotic link between SC and heroin use.

Funding

The National Institute for Health Research Public Health Research programme.

The Ability of Narcotic Detection Canines to Detect Illegal Synthetic Cathinones (Bath Salts)

Twelve certified narcotic detection canines were tested for their ability to detect confiscated illegal synthetic cathinones (bath salts). These canine teams were randomly assigned to two different groups and each group imprinted on one of two types of bath salts, ethylone and alpha-pyrrolidinovalerophenone (α-PVP), over the period of 1 month; while simultaneously documenting the imprinting procedure. The newly imprinted canines were validated by field testing and found to not only detect the imprinted bath salt to which they were trained, but they were able to detect other bath salts. The imprinting procedure and results are the first scientifically validated studies on the ability of canines to detect these harmful and illegal substances. Analytical headspace analysis using Solid Phase Microextraction (SPME) on several ethylone and α-PVP samples revealed compounds common in both. These compounds can be used to create a safe and reliable synthetic cathinone mimic training aid for canine teams.

An observational study on the sub-acute effects of mephedrone on mood, cognition, sleep and physical problems in regular mephedrone users

RATIONALE

Mephedrone (4-methylmethcathinone; 4-MMC) is a novel recreational drug similar to methylenedioxymethamphetamine (MDMA) and amphetamine. Several adverse effects have been reported, but little is known about its sub-acute effects.

OBJECTIVES

To study sub-acute effects of mephedrone over a period of 9 days.

METHODS

Recreational mephedrone users were recruited and followed over a time period of 9 days. It was recorded whether participants consumed mephedrone or not within the period of testing; those who did were compared to those who did not. Forty-six regular mephedrone users (22 males, 24 females) participated, 21 participants voluntarily opted to consume mephedrone 1-3 days after baseline and 25 opted to abstain. Participants were assessed at baseline on a multitude of measures and provided daily reports on cognition, sleep, mood, physical problems, mephedrone cravings and substance use on each subsequent day of the study. The study controlled for psychopathology, sleep, past and current substance use, impulsivity and demographics.

RESULTS

Those who consumed mephedrone reported persistent negative mood, physical problems and fatigue, compared to those who did not-after controlling for baseline group differences in sleep and subsequent alcohol and cannabis use.

CONCLUSIONS

The results provide the first prospective evidence of the duration and extent of specific undesirable sub-acute effects of mephedrone in regular recreational users and indicate sub-acute effects of mephedrone on mood, fatigue and physical symptoms.

Conditioned Reward of Opioids, but not Psychostimulants, is Impaired in GABA-A Receptor δ Subunit Knockout Mice

Extrasynaptic δ subunit-containing γ-aminobutyric acid type A receptors (δ-GABA_A Rs) are emerging as targets for a number of neuropsychopharmacological drugs, including the direct GABA site agonist gaboxadol and neuroactive steroids. Among other regions, these δ-GABA_A Rs are functionally expressed in the ventral tegmental area (VTA), the cell body region of mesocorticolimbic dopamine (DA) system important for motivated behaviours, and in the target region, the nucleus accumbens. Gaboxadol and neurosteroids induce VTA DA neuron plasticity ex vivo, by inhibiting the VTA GABA neurons, and aversive place conditioning, which are absent in the δ-GABA_A R knockout mice (δ-KO). It is not known whether δ-GABA_A Rs are important for the effects of other drugs, such as opioids (that also inhibit GABA neurons) and stimulants (that primarily elevate monoamine levels). Here, we used δ-KO mice and conditioned place preference (CPP) test to study the rewarding effects of morphine (20 mg/kg), methamphetamine (1 mg/kg) and mephedrone (5 mg/kg). Morphine-induced nociception was also assessed using tail-flick and hot-plate tests. We found that the δ-KO mice failed to express morphine-induced CPP, but that they were more sensitive to morphine-induced analgesia in the tail-flick test. In contrast, stimulant-induced CPP in the δ-KO mice was similar to that in the wild-type controls. Thus, the conditioned rewarding effect by opioids, but not that of stimulants, was impaired in the absence of δ-GABA_A Rs. Further studies are warranted to assess the potential of δ-GABA_A R antagonists as possible targets for reducing morphine reward and potentiating morphine analgesia.

Potential pro-oxidative effects of single dose of mephedrone in vital organs of mice

BACKGROUND

Mephedrone is a recreationally used synthetic cathinone, relatively new abusive substances with molecular structure similar to amphetamine. As there is still lack of scientific data regarding mechanisms of action as well as metabolism of mephedrone, especially in aspects other than neurotoxicity, addiction or behavioral changes, therefore we aimed, for the first time, to investigate potential pro-oxidative actions of a single dose of mephedrone in organs other than brain and its structures, i.e. in liver, kidneys, heart and spleen of Swiss mice.

METHODS

The following biomarkers of oxidative stress were measured: concentration of ascorbic acid (AA) and malondialdehyde (MDA) as well as total antioxidant capacity (TAC) of the tissues homogenates.

RESULTS

Our study revealed that mephedrone intoxication induces oxidative stress by reducing concentration of AA and TAC and increasing concentration of MDA in these organs.

CONCLUSIONS

Such occurred state of antioxidant-oxidant imbalance may be etiopathological factor of a number of severe diseases within cardiovascular, digestive as well as immunological systems.