Blood concentrations of a new psychoactive substance 4-chloromethcathinone (4-CMC) determined in 15 forensic cases

Simultaneous chemo- and enantio-separation of 2-, 3- and 4-chloro-methcatinones by high-performance liquid chromatography-tandem mass spectrometry and its application to oral fluid samples

A method of analysis was developed for the simultaneous chemo- and enantioseparation of 2-, 3-, and 4-chloromethcathinones by high-performance liquid chromatography tandem mass-spectrometry. The fast method enables the reliable identification of positional isomers of chloromethcathinones in biological samples. In addition, the same method can be used for the enantioselective quantitative determination of one of these compounds and its major phase-1 metabolites in biological fluids. The developed method was applied to oral fluid samples collected by police during routine random traffic control in Belgium from January to November, 2023. It was found that 3-CMC was more frequently abused compared to 4-CMC. Although some differences were observed between the concentrations of enantiomers in OF, most likely the drugs were abused in the racemic form. No abuse of 2-CMC was detected at the timepoint of sample collection.

Challenges encountered in the enantioselective analysis of new psychoactive substances exemplified by clephedrone (4-CMC)

In this study we report on efforts to develop an enantioselective method for the detection of the drug of abuse clephedrone (1-(4-chlorophenyl)-2-(methylamino)-1-propanone (4-chloromethcathinone, also known as 4-CMC or para-chloro-methcathinone)) and its phase-1 metabolites in human biological fluids. The major goal is not to only report results, but primarily to emphasize the various challenges encountered when developing a reliable analytical method for the detection and quantification of novel psychoactive substances (NPS) and their metabolites in the matrix of interest. Such challenges start with the lack of chemical stability of some NPS in biological matrices. Additionally, most often metabolites are unavailable in pure form to serve as analytical standards, just as deuterated standards for native drugs and metabolites are frequently not commercially available. Furthermore, if the NPS is chiral, enantiomerically pure standards with known absolute stereochemistry are required, as well as a stereochemical stability of a drug and its metabolites becomes an issue. In addition, the chirality of a NPS significantly increases the number of species to be detected in the sample and thus challenges the development of an adequate separation method. These issues are shortly addressed, and some solutions offered in this manuscript.

Investigation of stereochemical stability of 2-, 3- and 4-chloromethcathinones in various biological matrixes

The stereochemical stability of the popular drugs of abuse 2-, 3- and 4-chloromethcathinone was studied in the mobile phase used for the isolation of their enantiomers by high-performance liquid chromatography, as well as in various biological matrixes such as whole blood, saliva and urine. For 2-, 3-, and 4-chloromethcathinones the rate constants and half-lives of their first order racemization reaction was assessed. It was found that at 25 °C the racemization rate constant decreases in the order 2-CMC > 3-CMC > 4-CMC while their stereochemical stability in biological matrixes decreases in the order urine > saliva > whole blood. This information must be considered for the adequate storage of purified enantiomers in the collected fractions, as well as in the studies focused on their enantioselective transformation in the human body.

Determination of 3- and 4-chloromethcathinone interactions with plasma proteins: study involving analytical and theoretical methods

PURPOSE

The purpose of this paper was to determine 3- and 4-chloromethcathinone (3- and 4-CMC) binding degree and possible binding interaction modes with human serum albumin (HSA) using analytical and theoretical methods.

METHODS

Experimental determination of 3- and 4-CMC binding degree with HSA was performed using gas chromatography-tandem mass spectrometry preceded by the equilibrium dialysis (ED) and ultrafiltration (UF). Nuclear magnetic resonance (NMR) spectroscopy was used to determine 3- and 4-CMC epitope-binding maps and possible binding sites in HSA. The molecular docking and molecular dynamics were employed to obtain detailed information about binding modes of 3- and 4-CMC enantiomers in HSA.

RESULTS

As follows from the presented data, the degree of binding of 3- and 4-CMC is at a similar level of approx. 80%. This indicates a relatively strong binding of CMC to plasma proteins. The model studies employing the NMR spectroscopy and molecular simulations indicate that both CMCs bind to HSA. The whole 3- and 4-CMC molecules are embedded in the binding sites, with aromatic moieties being in the closest contact with the HSA residues. Moreover, conducted experiments show that  Sudlow site II is the main binding center for 3- and 4-CMC and  Sudlow site I acts as the secondary binding site.

CONCLUSIONS

Although many studies describe pharmacological and toxicological properties of synthetic cathinones (SC), the data taking SCs binding in plasma into consideration are scarce. To our knowledge, this is the first report presenting comprehensive experimental and theoretical characterization of 3- and 4-CMC binding with plasma proteins.

3-CMC, 4-CMC, and 4-BMC Human Metabolic Profiling: New Major Pathways to Document Consumption of Methcathinone Analogues?

Synthetic cathinones represent one of the largest and most abused new psychoactive substance classes, and have been involved in numerous intoxications and fatalities worldwide. Methcathinone analogues like 3-methylmethcathinone (3-MMC), 3-chloromethcathinone (3-CMC), and 4-CMC currently constitute most of synthetic cathinone seizures in Europe. Documenting their consumption in clinical/forensic casework is therefore essential to tackle this trend. Targeting metabolite markers is a go-to to document consumption in analytical toxicology, and metabolite profiling is crucial to support investigations. We sought to identify 3-CMC, 4-CMC, and 4-bromomethcathinone (4-BMC) human metabolites. The substances were incubated with human hepatocytes; incubates were screened by liquid chromatography-high-resolution tandem mass spectrometry and data were mined with Compound Discoverer (Themo Scientific). 3-CMC-positive blood, urine, and oral fluid and 4-CMC-positive urine and saliva from clinical/forensic casework were analyzed. Analyses were supported by metabolite predictions with GLORYx freeware. Twelve, ten, and ten metabolites were identified for 3-CMC, 4-CMC, and 4-BMC, respectively, with similar transformations occurring for the three cathinones. Major reactions included ketoreduction and N-demethylation. Surprisingly, predominant metabolites were produced by combination of N-demethylation and ω-carboxylation (main metabolite in 3-CMC-positive urine), and combination of β-ketoreduction, oxidative deamination, and O-glucuronidation (main metabolite in 4-CMC-positive urine). These latter metabolites were detected in negative-ionization mode only and their non-conjugated form was not detected after glucuronide hydrolysis; this metabolic pathway was never reported for any methcathinone analogue susceptible to undergo the same transformations. These results support the need for comprehensive screening strategies in metabolite identification studies, to avoid overlooking significant metabolites and major markers of consumption.

Toxicity of the New Psychoactive Substance (NPS) Clephedrone (4-Chloromethcathinone, 4-CMC): Prediction of Toxicity Using In Silico Methods for Clinical and Forensic Purposes

This study reports the first application of in silico methods to assess the toxicity of 4-chloromethcathinone (4-CMC), a novel psychoactive substance (NPS). Employing advanced toxicology in silico tools, it was possible to predict crucial aspects of the toxicological profile of 4-CMC, including acute toxicity (LD50), genotoxicity, cardiotoxicity, and its potential for endocrine disruption. The obtained results indicate significant acute toxicity with species-specific variability, moderate genotoxic potential suggesting the risk of DNA damage, and a notable cardiotoxicity risk associated with hERG channel inhibition. Endocrine disruption assessment revealed a low probability of 4-CMC interacting with estrogen receptor alpha (ER-α), suggesting minimal estrogenic activity. These insights, derived from in silico studies, are critical in advancing the understanding of 4-CMC properties in forensic and clinical toxicology. These initial toxicological findings provide a foundation for future research and aid in the formulation of risk assessment and management strategies in the context of the use and abuse of NPSs.

Interpretative problems due to the presence of chloromethcathinone isomers in the biological material from postmortem cases

While many new psychoactive substances often disappear from the drug market rather quickly, some, such as synthetic cathinones (SCs), still remain due to their popularity among users. The current knowledge of SC concentrations in blood samples is based mainly on the published case reports of intoxications or fatalities caused by SC intake. The aim of the present study was to present and interpret the obtained toxicological analysis results of these cases, in which it was possible to determine or detect the presence of one of the isomers of chloromethcathinone (CMC) along with its intake biomarker-dihydro-CMC. These cases include 27 deaths reported at the Department of Forensic Medicine in Kraków in 2016-2022. CMC constitutes a major toxicological opinion challenge, in terms of toxicological evaluation of poisonings. As presented in this paper, a significant problem is its stability in the biological material and practices in the reporting of the obtained data. It is therefore important to monitor potential intake biomarkers that may show greater stability in the biological material than the parent drug. In the case of CMC isomers, the good biomarker of intake is the dihydro-CMC metabolite, which was detected in the blood sample in every case presented, even with the absence of the parent substance. Interpretation of the results obtained for CMC in terms of assessing their toxicity and possible cause of death is difficult. However, it should be taken into account that in cases of new psychoactive substance poisoning, an in-depth risk assessment is mandatory and the opinion of the unpredictability of the effects is taken as a principle.

Neurochemical and Cardiovascular Effects of 4-Chloro Ring-Substituted Synthetic Cathinones in Rats

Synthetic cathinones are a class of new psychoactive substances that display psychomotor stimulant properties, and novel cathinone analogs continue to emerge in illicit drug markets worldwide. The aim of the present study was to characterize the pharmacology of 4-chloro ring-substituted cathinones that are appearing in illicit drug markets compared with the effects of 4-methylmethcathinone (mephedrone). Synaptosomes were prepared from rat caudate for dopamine transporter (DAT) assays or from whole brain minus caudate and cerebellum for norepinephrine transporter (NET) and serotonin transporter (SERT) assays. Findings from transporter uptake inhibition and release assays showed that mephedrone and 4-chloromethcathinone (4-CMC) function as substrates at DAT, NET, and SERT, with similar potency at all three transporters. In contrast, 4-chloro-α-pyrrolidinopropiophenone (4-CαPPP) was an uptake inhibitor at DAT and NET, with similar potency at each site, but had little activity at SERT. 4-Chloroethcathinone (4-CEC) was a low-potency uptake inhibitor at DAT and NET but a substrate at SERT. In rats implanted with telemetry transmitters, mephedrone and 4-CMC increased blood pressure, heart rate, and locomotor activity to a similar extent. 4-CEC and 4-CαPPP were less potent at increasing blood pressure and had modest stimulatory effects on heart rate and activity. 4-CMC also transiently decreased temperature at the highest dose tested. All three 4-chloro ring-substituted cathinones are biologically active, but only 4-CMC has potency comparable to mephedrone. Collectively, our findings suggest that 4-CMC and other 4-chloro cathinones may have abuse potential and adverse effects in humans that are analogous to those associated with mephedrone. SIGNIFICANCE STATEMENT: The 4-chloro ring-substituted cathinones all produced significant cardiovascular stimulation, with 4-chloromethcathinone (4-CMC) showing potency similar to mephedrone. All of the drugs are likely to be abused given their effects at the dopamine transporter, particularly 4-CMC.

Synthesis of emerging cathinones and validation of a SPE GC-MS method for their simultaneous quantification in blood

Over the past 15 years, synthetic cathinones have emerged as an important class of new psychoactive substances (NPS) worldwide. The proliferation of these psychostimulants and their sought-after effects among recreational drug users pose a serious threat to public health and enormous challenges to forensic laboratories. For forensic institutions, it is essential to be one step ahead of covert laboratories, foreseeing the structural changes possible to introduce in the core skeleton of cathinones while maintaining their stimulating activity. In this manner, it is feasible to equip themselves with standards of possible new cathinones and validated analytical methods for their qualitative and quantitative detection. Therefore, the aim of the work herein described was to synthesize emerging cathinones based on the evolving patterns in the illicit drug market, and to develop an analytical method for their accurate determination in forensic situations. Five so far unreported cathinones [4'-methyl-N-dimethylbuphedrone (4-MDMB), 4'-methyl-N-ethylbuphedrone (4-MNEB), 4'-methyl-N-dimethylpentedrone (4-MDMP), 4'-methyl-N-dimethylhexedrone (4-MDMH), and 4'-methyl-N-diethylbuphedrone (4-MDEB)] and a sixth one, 4'-methyl-N-ethylpentedrone, already reported to EMCDDA and also known as 4-MEAP, were synthesized and fully characterized by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). An analytical method for the simultaneous quantification of these cathinones in blood, using solid phase extraction (SPE) combined with gas chromatography-mass spectrometry (GC-MS) was developed and validated. The results prove that this methodology is selective, linear, precise, and accurate. For all target cathinones, the extraction efficiency was higher than 73%, linearity was observed in the range of 10 (lower limit of quantification, LLOQ) to 800 ng/mL, with coefficients of determination higher than 0.99, and the limits of detection (LODs) were 5 ng/mL for all target cathinones. The stability of these cathinones in blood matrices is dependent on the storage conditions; 4-MNEB is the most stable compound and 4-MDMH is the least stable compound. The low limits obtained allow the detection of the compounds in situations where they are involved, even if present at low concentrations.

Metabolic stability and metabolite profiling of emerging synthetic cathinones

Synthetic cathinones constitute the second largest groups of new psychoactive substances (NPS), which are especially popular among adolescents and young adults. Due to their potential toxicity, the recreational use of these NPS constitute a serious worldwide public health problem. However, their fast appearance in the market renders the continuous updating of NPS information highly challenging for forensic authorities. The unavailability of pharmacokinetic data for emerging NPS is critical for forensic and clinical verifications. With the ultimate goal of having a proactive approach towards the NPS issue, high resolution mass spectrometry was used in the current work to assess preliminary pharmacokinetic data for 8 selected cathinones: 4 reported substances (4-CIC, 3-CMC, 4-CMC and 4-MEAP) and 4 previously unreported ones (3-CIC, 4-MDMB, 4-MNEB and 4-MDMP) for which the emergence on the NSP market is expected to be eminent, were also included in this study. Based on the calculation of pharmacokinetic parameters, half-life and intrinsic clearance, 4-CMC and 4-MDMB are low and high clearance compounds, respectively, and all the remaining cathinones included in this study are intermediate clearance compounds. This fact anticipates the key role of metabolites as suitable biomarkers to extend detection windows beyond those provided by the parent cathinones. Reduction of the keto group and hydroxylation on the alkyl chains were the common metabolic pathways identified for all cathinones. However, the relative importance of these metabolic transformations is dependent on the cathinone substituents. The glucuronic acid conjugation to metabolites stemming for keto group reduction constituted the sole Phase II transformation identified. To our knowledge, this study constitutes the first metabolite profiling of the already reported synthetic cathinones 4-CIC, 3-CMC and 4-CMC. Noteworthy is the fact that 3-CMC accounts for almost a quarter of the quantity of powders seized during 2020. The analytical methods developed, and the metabolites characterized, are now available to be included in routine screening methods to attest the consumption of the 8 cathinones studied.

Fatal cases involving new psychoactive substances and trends in analytical techniques

New psychoactive substances (NPS) are an emerging public health issue and deaths are commonly associated with polydrug abuse. Moreover, the number of new substances available is constantly increasing, causing intoxications in low doses, characteristics that impose to toxicology and forensic laboratories to keep routine methods up to date, with high detectability and constantly acquiring new analytical standards. Likewise, NPS metabolites and respective elimination pathways are usually unknown, making it difficult the detection and confirmation of the drug involved in the fatal case in an analytical routine. A literature search was performed on PubMed, Scopus and Web of Science databases for papers related to chromatographic analyses from fatal cases related to NPS use published from 2016 to 2021. A total of 96 papers were retrieved and reviewed in this study. Opioids, synthetic cathinones, phenethylamines/amphetamines and cannabinoids were the NPS classes most found in the fatal cases. In many cases, multiple compounds were detected in the biological samples, including prescription and other illegal drugs. Liquid chromatography-tandem mass spectrometry, an alternative to overcome the gas chromatography-mass spectrometry limitations for some compounds, was the analytical technique most used in the studies, and high resolution mass spectrometry was often applied to NPS metabolite investigation and structural characterization and identification of unknown compounds. Toxicological screening and quantitation methods need to be continuously updated to include new substances that are emerging on the drug market that can be fatal at very low doses.

Unsupervised convolutional variational autoencoder deep embedding clustering for Raman spectra

Unsupervised deep learning methods place increased emphasis on the process of cluster analysis of unknown samples without requiring sample labels. Clustering algorithms based on deep embedding networks have been recently developed and are widely used in data mining, speech processing and image recognition, but barely any of them have been used on spectra data. This study presents an unsupervised clustering algorithm for Raman spectra, called the convolutional variational autoencoder deep embedding clustering method (CVDE). It improves the network structure of the multi-layer perception (MLP) that is commonly used in other methods based on the VAE-GMM model, like VaDE, by replacing the hidden fully connected layer in the MLP with three convolution layers and two pooling layers for better clustering on the Raman spectra. The three convolution layers extend vertical channels to learn features, while pooling layers directly reduce the horizontal coding dimensions to prevent gradient explosion and overfitting. Furthermore, such network structures can easily incorporate the gradient-weighted class activation mapping (Grad-Cam) method to visualise the importance of spectral features for clustering, facilitating network tuning and spectral difference analysis. Moreover, through comparative experiments, CVDE has proven that it affords better clustering performance than current advanced clustering methods on not only the MNIST dataset but also two sets of Raman spectra: soybean oil Raman spectra with very small Raman feature differences and drug Raman spectra with a small data size. The clustering accuracies of these three datasets reach 94.48%, 90.43% and 98.70% respectively. Thus, CVDE is suitable for applications in static spectra, such as Raman spectra and LIBS spectra, and is more versatile than supervised methods in the spectral and chemical analysis fields.

Toxicological Analysis of Intoxications with Synthetic Cathinones

Synthetic cathinones (SCs) are currently the second largest and the second most frequently seized group of new psychoactive substances. They are sold as replacements for controlled stimulants such as amphetamine, cocaine and 3,4-methylenedioxymethamphetamine. Administration of low doses of SCs can cause euphoria and increased alertness, and administration of high doses or chronic use of cathinones can cause serious adverse effects such as hallucinations, delirium, hyperthermia and tachycardia. In the years 2013-2019 in our practice, as many as 16 different SCs were detected in biological materials. This article lists the observed concentrations in 39 fatal and 18 non-fatal cases, in which a single SC as well as an SC in combination with amphetamine or ethyl alcohol were detected and quantified in biological materials. The quantitative analyses were carried out by liquid chromatography with tandem mass spectrometry. The analyzed cases of taking SCs were associated with intoxication (2 cases), fatal intoxication (36), driving under the influence of drugs (10) and other circumstances (9) such as violence, insulting an officer and holding a hostage. Taking SCs has serious side effects that can lead to multiple organ failure and death. Screening for the presence of SCs in biological materials should be part of the routine course of treatment in intoxication cases, both at the stage of clinical diagnosis and at the stage of forensic toxicological analysis. Ethyl alcohol and amphetamine may contribute to increased SC toxicity. These data could be valuable for further interpretation of other results from toxicological analyses.

Overview of analytical methods for determining novel psychoactive substances, drugs and their metabolites in biological samples

Recent years have witnessed a growing in interest in psychoactive substances, particularly those available in e-commerce. These have led to an increase in the number of drug-related poisonings, deaths, and road accidents. Illegal drugs are available on an unprecedented scale and cause previously unknown adverse effects, which creates a challenge for analysts to find rapid methods for identifying these substances and taking appropriate action in the shortest possible time. New psychoactive substances (NPSs) can be lethal at very low concentrations, which give particularly serious cause for concern. These drugs are easily accessible and often regarded (or claimed) to be safe, which encourages many people, in particular young people, to try them. The widespread use of these substances is compounded by the awareness that they are difficult to detect with the existing rapid screening tests. Simple, fast, sensitive, and specific methods for determining the largest possible number of black-market psychoactive substances and their metabolites are therefore essential. Such methods will facilitate treatment and increase the effectiveness of measures aiming to reduce drug addiction. The objective of this review article was to critically compare the most commonly used analytical methods for determining NPS and their metabolites in biological material, with special emphasis on the sample preparation process, and to highlight the possibilities offered by the existing analytical methods.

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.

A Review of Synthetic Cathinone-Related Fatalities From 2017 to 2020

BACKGROUND

Synthetic cathinones (SCs) are designer analogs of the natural active principle of khat. Since their appearance on the black market in 2003, their popularity has increased annually, and they have become the most seized class of new psychoactive substances reported to the UNODC Early Warning Advisory system. The constant introduction of newly synthesized molecules makes this issue difficult to monitor. The authors reviewed the most recent SC-related fatalities worldwide to highlight new trends of consumption, reporting acute pharmacological and toxicological symptoms, scene investigations, analytical methods, and reported SC concentrations in diverse biological matrices.

METHODS

A literature search was performed using scientific databases such as PubMed, Scopus, Science Direct, Web of Science, and Research Gate to identify relevant scientific publications from 2017 to 2020. In addition, a search was conducted through the EU EWS.

RESULTS

From 2017 to 2020, 31 different SCs were identified in 75 reported fatal intoxications in the literature, alone or in combination with other substances. The most abused SCs were N-ethylpentylone, N-ethylhexedrone, and 4-chloromethcathinone. The EU EWS included less detail on 72 additional SC-related fatalities from 2017 to 2020.

CONCLUSIONS

New SCs continuously replace older natural and synthetic stimulant drugs, making determining the cause of death difficult. Analytical methods and high-performance mass spectrometry instruments are essential to detect the low concentrations of these potent new SCs. Little data are available on the pharmacology of these new drugs; the evaluation of toxicological antemortem and postmortem findings provides critical data on the drug's pharmacology and toxicology and for the interpretation of new SC cases.

Fatal intoxication with U-47700 in combination with other NPS (N-ethylhexedrone, adinazolam, 4-CIC, 4-CMC) confirmed by identification and quantification in autopsy specimens and evidences

Purpose

We present a case of fatal intoxication with U-47700 in combination with other NPS (N-ethylhexedrone, adinazolam, 4-chloro-N-isopropylcathinone (4-CIC), 4-chloromethcathinone (4-CMC) and sertraline) confirmed by identification and quantification in biological materials and evidences found at the scene in 2017 in Poland.

Methods

Blood and urine samples were extracted with ethyl acetate from alkaline medium (pH 9); powders/crystals were diluted with methanol. The analysis was carried out using ultra-high-performance liquid chromatography–tandem mass spectrometry. Validation criteria were evaluated for blood and urine at the concentrations of 10 and 100 ng/mL.

Results

The validation parameters of the method were within acceptable ranges. In the presented case, the determined concentrations of drugs were as follows, in blood: U-47700, 1470 ng/mL; N-ethylhexedrone, 58 ng/mL; adinazolam, 18 ng/mL; 4-CIC, 8.0 ng/mL; 4-CMC, 1.7 ng/mL; in urine: U-47700, 3940 ng/mL; N-ethylhexedrone, 147 ng/mL; adinazolam, 82 ng/mL; 4-CIC, 130 ng/mL; 4-CMC, 417 ng/mL. Sertraline (blood, 89 ng/mL; urine, 32 ng/mL) was also determined in both materials. The same substances were also found in 5 powders/crystals: U-47700 (12% by weight), N-ethylhexedrone (54%), adinazolam (14%), 4-CIC (23%), 4-CMC (26%). After 775 days of storage, biological samples at + 4 °C, the most stable substance was sertraline and the less, synthetic cathinones, especially 4-CIC and 4-CMC.

Conclusions

The described case of fatal intoxication with NPS presented postmortem concentrations of U-47700, 4-CMC, N-ethylhexedrone, adinazolam and 4-CIC for the first time in the literature. The paper also showed stability study of these substances stored at + 4 °C for 775 days.

Four Synthetic Cathinones: 3-Chloromethcathinone, 4-Chloromethcathinone, 4-Fluoro-α-Pyrrolidinopentiophenone, and 4-Methoxy-α-Pyrrolidinopentiophenone Produce Changes in the Spontaneous Locomotor Activity and Motor Performance in Mice with Varied Profiles

Two chloromethcathinones, 3-chloromethcathinone (3-CMC) and 4-chloromethcathinone (4-CMC), and two para-substituted α-pyrrolidinophenones, 4-methoxy-α-pyrrolidinopentiophenone (4-MeO-PVP) and 4-fluoro-α-pyrrolidinopentiophenone (4-F-PVP), represent synthetic cathinones, the second most frequently abused group of new psychoactive substances (NPSs), which has aroused a worldwide health concern in the last decade. Synthetic cathinones act as psychostimulants by elevating extracellular levels of monoaminergic neurotransmitters. This study investigates effects of 3-CMC, 4-CMC, 4-MeO-PVP, and 4-F-PVP on the spontaneous locomotor activity and motor performance of mice. Additionally, neurotoxicity of substituted methcathinones against SH-SY5Y neuroblastoma cells was evaluated. All test cathinones stimulate in a dose-dependent manner horizontal locomotor activity of mice. Consistently to our prior findings, pyrrovalerones, but not methcathinone derivatives, produce dose-dependent elevation of vertical locomotor activity (rearing behavior). None of the tested compounds decreases the time spent on the accelerating rotarod, pointing to the lack of considerable motor disability in mice after acute exposition. Only 4-MeO-PVP at the high tested dose (20 mg/kg) increases motor performance of mice. Considering that α-pyrrolidinophenones are highly potent and selective DA uptake inhibitors, while chloromethcathinones enhance non-selective DA/5-HT release, we suggest that the increase of vertical locomotor activity and performance on rotarod in mice may serve as a behavioral indicator of the monoaminergic profile of synthetic cathinones. Finally, this study gives first insights into cytotoxicity of both 3-CMC and 4-CMC displayed against SH-SY5Y cells, which emerges and intensifies after prolonged incubation, suggesting the indirect mechanism of action, unrelated to interactions with monoamine transporters.

Interpol review of toxicology 2016-2019

This review paper covers the forensic-relevant literature in toxicology from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20.Papers%202019.pdf.

Para-Halogenation of Amphetamine and Methcathinone Increases the Mitochondrial Toxicity in Undifferentiated and Differentiated SH-SY5Y Cells

Halogenation of amphetamines and methcathinones has become a common method to obtain novel psychoactive substances (NPS) also called “legal highs”. The para-halogenated derivatives of amphetamine and methcathinone are available over the internet and have entered the illicit drug market but studies on their potential neurotoxic effects are rare. The primary aim of this study was to explore the neurotoxicity of amphetamine, methcathinone and their para-halogenated derivatives 4-fluoroamphetamine (4-FA), 4-chloroamphetamine (PCA), 4-fluoromethcathinone (4-FMC), and 4-chloromethcathinone (4-CMC) in undifferentiated and differentiated SH-SY5Y cells. We found that 4-FA, PCA, and 4-CMC were cytotoxic (decrease in cellular ATP and plasma membrane damage) for both cell types, whereby differentiated cells were less sensitive. IC₅₀ values for cellular ATP depletion were in the range of 1.4 mM for 4-FA, 0.4 mM for PCA and 1.4 mM for 4-CMC. The rank of cytotoxicity observed for the para-substituents was chloride > fluoride > hydrogen for both amphetamines and cathinones. Each of 4-FA, PCA and 4-CMC decreased the mitochondrial membrane potential in both cell types, and PCA and 4-CMC impaired the function of the electron transport chain of mitochondria in SH-SY5Y cells. 4-FA, PCA, and 4-CMC increased the ROS level and PCA and 4-CMC induced apoptosis by the endogenous pathway. In conclusion, para-halogenation of amphetamine and methcathinone increases their neurotoxic properties due to the impairment of mitochondrial function and induction of apoptosis. Although the cytotoxic concentrations were higher than those needed for pharmacological activity, the current findings may be important regarding the uncontrolled recreational use of these compounds.

Hyperthermia Increases Neurotoxicity Associated with Novel Methcathinones

Hyperthermia is one of the severe acute adverse effects that can be caused by the ingestion of recreational drugs, such as methcathinones. The effect of hyperthermia on neurotoxicity is currently not known. The primary aim of our study was therefore to investigate the effects of hyperthermia (40.5 °C) on the neurotoxicity of methcathinone (MC), 4-chloromethcathinone (4-CMC), and 4-methylmethcathinone (4-MMC) in SH-SY5Y cells. We found that 4-CMC and 4-MMC were cytotoxic (decrease in cellular ATP and plasma membrane damage) under both hyper- (40.5 °C) and normothermic conditions (37 °C), whereby cells were more sensitive to the toxicants at 40.5 °C. 4-CMC and 4-MMC impaired the function of the mitochondrial electron transport chain and increased mitochondrial formation of reactive oxygen species (ROS) in SH-SY5Y cells, which were accentuated under hyperthermic conditions. Hyperthermia was associated with a rapid expression of the 70 kilodalton heat shock protein (Hsp70), which partially prevented cell death after 6 h of exposure to the toxicants. After 24 h of exposure, autophagy was stimulated by the toxicants and by hyperthermia but could only partially prevent cell death. In conclusion, hyperthermic conditions increased the neurotoxic properties of methcathinones despite the stimulation of protective mechanisms. These findings may be important for the understanding of the mechanisms and clinical consequences of the neurotoxicity associated with these compounds.

Successful use of a novel lux® i-Amylose-1 chiral column for enantioseparation of "legal highs" by HPLC

Bath salts, fumigations, cleaners and air fresheners, behind these terms substances are hidden, which count as "Legal Highs". These fancy names are used to pretend Legal Highs as harmless compounds, to circumvent legal regulations for marketing as well as to increase the sales. Besides classic illicit drugs of synthetic origin such as amphetamines, cocaine and MDMA, the trade of these compounds, also known as new psychoactive substances (NPS), is not uncommon today. In many countries, NPS are still not subject to drug control. Among them, there are stimulants such as new amphetamine derivatives or cathinones, which possess a chiral centre. Little is known about the fact that the two possible enantiomers may differ in their pharmacological effect. The aim of this study was to test a novel HPLC column for the enantioseparation of a set of 112 NPS coming from different chemical groups and collected by internet purchases during the years 2010-2018. The CSP, namely Lux® 5 μm i-Amylose-1, LC Column 250 x 4.6 mm, was run in normal phase mode under isocratic conditions, UV detection was performed at 245 nm and 230 nm, injection volume was 10 μl and flow rate was 1 ml/min. With a mobile phase consisting of n-hexane/isopropanol/diethylamine (90:10:0.1), herein, 79 NPS were resolved into their enantiomers successfully, for 37 of them baseline resolution was achieved. After increase of lipophily of the mobile phase to 99:1:0.1, another 27 compounds were baseline separated. It was found that all separated NPS are traded as racemic compounds.

Locomotor activity and discriminative stimulus effects of five novel synthetic cathinone analogs in mice and rats

BACKGROUND

The development of novel synthetic psychoactive substances continues to accelerate. There are little or no data on the pharmacological mechanisms, behavioral effects, or abuse liability of many of the newer compounds, despite increasing reports of severe adverse effects in recreational users.

METHODS

The current study investigated the discriminative stimulus and locomotor stimulant effects of a group of synthetic cathinone analogs: N-ethylpentylone, dimethylone, dibutylone, clephedrone, 3',4'-tetramethylene-α-pyrrolidinovalerophenone (TH-PVP). Locomotor activity was assessed in an open-field assay using Swiss-Webster mice. Discriminative stimulus effects were assessed in Sprague-Dawley rats trained to discriminate either cocaine, methamphetamine or MDMA from vehicle.

RESULTS

N-Ethylpentylone, dimethylone, dibutylone and clephedrone increased locomotor activity. Maximal effects were similar among the test compounds. Relative potencies were: methamphetamine > N-ethylpentylone > clephedrone > dimethylone > MDMA > cocaine > dibutylone. TH-PVP dose-dependently depressed locomotor activity. N-Ethylpentylone, dimethylone, dibutylone and clephedrone substituted fully for the discriminative stimulus effects of methamphetamine. N-Ethylpentylone, dibutylone and clephedrone fully substituted for cocaine, whereas dimethylone produced a maximum of 67% drug-appropriate responding. Dimethylone, dibutylone and clephedrone fully substituted for MDMA, whereas N-ethylpentylone produced only 50% drug-appropriate responding. TH-PVP produced a maximum of 38% methamphetamine-appropriate responding, 50% cocaine-appropriate responding, and less than 1% MDMA-appropriate responding.

CONCLUSIONS

These data provide initial evidence that the novel psychoactive substances N-ethylpentylone, dimethylone, dibutylone, and clephedrone demonstrate potential for abuse as psychostimulants and/or club drugs, given their ability to stimulate locomotor activity and their substitution for the discriminative stimulus effects of methamphetamine, cocaine and/or MDMA. TH-PVP has minimal activity in the assays tested and may have little or no abuse liability.

Para-Halogenation Affects Monoamine Transporter Inhibition Properties and Hepatocellular Toxicity of Amphetamines and Methcathinones

Halogenated derivatives of amphetamine-type stimulants are appearing on the drug market, often with altered pharmacological profile and sometimes different legal status compared to the non-halogenated substances. The aim of the present study was to investigate the pharmacological profile and hepatocellular toxicity of para-halogenated amphetamines and cathinones. The potential of amphetamine, 4-fluoroamphetamine, 4-chloroamphetamine, methcathinone, 4-fluoromethcathinone, and 4-chloromethcathinone to inhibit the monoamine transporters for norepinephrine, dopamine, and serotonin was determined in transporter-transfected human embryonic kidney 293 cells. Cell membrane integrity, ATP content, oxygen consumption rate, and superoxide levels were measured in human hepatoma HepG2 cells after exposure to the substances for 24 h. All compounds inhibited the norepinephrine transporter at submicromolar concentrations and the dopamine transporter at low micromolar concentrations. The selectivity of the compounds to inhibit the dopamine versus serotonin transporter decreased with increasing size of the para-substituent, resulting in potent serotonin uptake inhibition for the halogenated derivatives. All substances depleted the cellular ATP content at lower concentrations (0.25–2 mM) than cell membrane integrity loss occurred (≥0.5 mM), suggesting mitochondrial toxicity. The amphetamines and 4-chloromethcathinone additionally impaired the mitochondrial respiratory chain, confirming mitochondrial toxicity. The following toxicity rank order for the para-substituents was observed: chloride > fluoride > hydrogen. In conclusion, para-halogenation of stimulants increases the risk for serotonergic neurotoxicity. Furthermore, para-halogenation may increase hepatic toxicity mediated by mitochondrial impairment in susceptible users.