4-Methylthioamphetamine

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Helena Carmo - One of the best experts on this subject based on the ideXlab platform.

  • An insight into the hepatocellular death induced by amphetamines, individually and in combination: the involvement of necrosis and apoptosis
    Archives of Toxicology, 2013
    Co-Authors: Diana Dias Da Silva, Helena Carmo, Adam Lynch, Elisabete Silva
    Abstract:

    The liver is a vulnerable target for amphetamine toxicity, but the mechanisms involved in the drug’s hepatotoxicity remain poorly understood. The purpose of the current research was to characterize the mode of death elicited by four amphetamines and to evaluate whether their combination triggered similar mechanisms in immortalized human HepG2 cells. The obtained data revealed a time- and temperature-dependent mortality of HepG2 cells exposed to 3,4-methylenedioxymethamphetamine (MDMA, ecstasy ; 1.3 mM), methamphetamine (3 mM), 4-Methylthioamphetamine (0.5 mM) and d -amphetamine (1.7 mM), alone or combined (1.6 mM mixture). At physiological temperature (37 °C), 24-h exposures caused HepG2 death preferentially by apoptosis, while a rise to 40.5 °C favoured necrosis. ATP levels remained unaltered when the drugs where tested at normothermia, but incubation at 40.5 °C provoked marked ATP depletion for all treatments. Further investigations on the apoptotic mechanisms triggered by the drugs (alone or combined) showed a decline in BCL - 2 and BCL -_ XL mRNA levels, with concurrent upregulation of BAX , BIM , PUMA and BID genes. Elevation of Bax, cleaved Bid, Puma, Bak and Bim protein levels was also seen. To the best of our knowledge, Puma, Bim and Bak have never been linked with the toxicity induced by amphetamines. Time-dependent caspase-3/-7 activation, but not mitochondrial membrane potential (∆ψ_m) disruption, also mediated amphetamine-induced apoptosis. The cell dismantling was confirmed by poly(ADP-ribose)polymerase proteolysis. Overall, for all evaluated parameters, no relevant differences were detected between individual amphetamines and the mixture (all tested at equieffective cytotoxic concentrations), suggesting that the mode of action of the amphetamines in combination does not deviate from the mode of action of the drugs individually, when eliciting HepG2 cell death.

  • Combination effects of amphetamines under hyperthermia - the role played by oxidative stress.
    Journal of Applied Toxicology, 2013
    Co-Authors: Diana Silva, Elisabete Silva, Helena Carmo
    Abstract:

    Rise in body temperature is a life-threatening consequence of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) abuse. We evaluated the impact of hyperthermia on the cytotoxicity of combinations of MDMA and three other amphetamines, often co-ingested. For this, Hep G2 cells were exposed to MDMA, d-amphetamine, methamphetamine and 4-Methylthioamphetamine, individually or combined, at 40.5 °C. The results were compared with normothermia data (37.0 °C). Mixture additivity expectations were calculated by independent action and concentration addition (CA) models. To delineate the mechanism(s) underlying the elicited effects, a range of stress endpoints was evaluated, including quantification of reactive oxygen/nitrogen species (ROS/RNS), lipid peroxidation, reduced/oxidized glutathione (GSH/GSSG), ATP and mitochondrial membrane potential (Δψm) changes. Our data show that, in hyperthermia, amphetamines acted additively and mixture effects were accurately predicted by CA. At 40.5 °C, even slight increases in the concentrations of each drug/mixture promoted significant rises in cytotoxicity, which quickly shifted from roughly undetectable to maximal mortality. Additionally, the increase of RNS/ROS production, decrease of GSH, ATP depletion and mitochondrial impairment were exacerbated under hyperthermia. Importantly, when equieffective cytotoxic concentrations of the mixture and individual amphetamines were compared for all tested stress endpoints, mixture effects did not deviate from those elicited by individual treatments, suggesting that these amphetamines have a similar mode of action, which is not altered in combination. Concluding, our data indicate that amphetamine mixtures produce deleterious effects, even when individual drugs are combined at negligible concentrations. These effects are strongly exacerbated in hyperthermia, emphasizing the potential increased risks of ecstasy intake, especially when hyperthermia occurs concurrently with polydrug abuse. Copyright © 2013 John Wiley & Sons, Ltd.

  • The risky cocktail: what combination effects can we expect between ecstasy and other amphetamines?
    Archives of Toxicology, 2013
    Co-Authors: Diana Dias Da Silva, Helena Carmo, Elisabete Silva
    Abstract:

    The recreational and illicit use of amphetaminic designer compounds, specially 3,4-methylenedioxymethamphetamine (MDMA; Ecstasy ), is of concern worldwide. Such psychostimulating drugs are frequently present as complex mixtures in ‘rave’ pills, making concomitant polysubstance use a common trend. However, the understanding of possible combination effects with these substances is still scarce. The present study was aimed at predicting the cytotoxic effects of mixtures of four amphetaminic derivatives: MDMA, methamphetamine, 4-Methylthioamphetamine and d-amphetamine in a human hepatoma cell line. Concentration–response curves for all single-mixture components were recorded by the MTT assay. Data obtained for individual agents were then used to compute the additivity expectations for mixtures of definite composition, using the pharmacological models of concentration addition (CA) and independent action . By comparing the predicted calculations with the experimentally observed effects, we concluded that CA accurately predicts the combination of amphetamines, which act together to generate additive effects over a large range of concentrations. Notably, we observed substantial mixture effects even when each drug was present at low concentrations, which individually produced unnoticeable effects. Nonetheless, for all tested mixtures, a small deviation from additivity was observed towards higher concentrations, particularly at high effect levels. A possible metabolic interaction, which could explain such deviation, was investigated, and it was observed that at higher mixture concentrations increased MDMA metabolism could be contributing to divergences from additivity. In conclusion, the present work clearly demonstrates that potentially harmful interactions among amphetaminic drugs are expected when these drugs are taken concomitantly.

  • CYP2D6 increases toxicity of the designer drug 4-Methylthioamphetamine (4-MTA).
    Toxicology, 2006
    Co-Authors: Helena Carmo, Marc Brulport, Matthias Hermes, Franz Oesch, Douwe De Boer, Fernando Remião, Félix Carvalho, Michael R. Schön, Niels Krebsfaenger, Johannes Doehmer
    Abstract:

    Abstract 4-Methylthioamphetamine (4-MTA) belongs to a group of new amphetamine derivatives that is usually sold as “ecstasy” or “flatliners” on the illicit drug market. Large interindividual differences in 4-MTA mediated toxicity have been reported in humans. Therefore, we tested whether CYP2D6 or its variant alleles as well as CYP3A4 influence the susceptibility to 4-MTA. For this purpose, we used the colony formation assay with Chinese hamster lung fibroblast V79 cells expressing human wild-type CYP2D6 (CYP2D6*1), the low activity alleles CYP2D6*2, CYP2D6*9, as well as human CYP3A4. The obtained results showed that the expression of wild type CYP2D6*1 clearly enhanced the susceptibility to the cytotoxic effects of 4-MTA compared with the parental cells devoid of CYP-dependent enzymatic activity. Toxicity in V79 CYP2D6*1 was also higher compared to the V79 cell lines expressing the low activity alleles CYP2D6*2 and CYP2D6*9. In contrast to CYP2D6, the CYP3A4 isoenzyme did not enhance 4-MTA toxicity. In conclusion, our results suggest that CYP2D6 rapid metabolizers may be more susceptible to 4-MTA toxicity than CYP2D6 poor metabolizers.

  • Simultaneous determination of amphetamine derivatives in human urine after SPE extraction and HPLC-UV analysis.
    Biomedical Chromatography, 2004
    Co-Authors: Maria Elisa Soares, Helena Carmo, Fernando Remião, Félix Carvalho, Márcia Carvalho, Maria De Lourdes Bastos
    Abstract:

    Amphetamine derivatives are a class of compounds increasingly abused as recreational drugs in various regions of the world. Although d-amphetamine (AMPH) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) are among the most commonly used, the abuse of other designer drugs such as 4-bromo-2,5-dimethoxyphenethylamine (2C-B) and 4-Methylthioamphetamine (4-MTA) and their involvement in acute intoxications has been increasingly reported. There is evidence that abusers ingest these compounds either alone or in combination and the respective monitoring is important for both legal and health care purposes in hospital emergency. In the present study a simple and clean solid-phase extraction procedure from urine of AMPH and MDMA, and their major metabolites p-hydroxyamphetamine (OH-AMPH) and methylenedioxyamphetamine (MDA) and 2C-B and 4-MTA was developed. Analysis was performed by HPLC-UV and the precision of the technique was between 2.9 and 5.3% for all compounds. For the overall procedure, the precision values were between 3.3 and 5.9%. Recoveries obtained from spiked urines at three concentration levels were better than 84 ± 4% for the six compounds. The limit of detection of the method for the compounds (between 5.3 and 84.0 ng) enables their identification in urine after ingestion of fatal and non-fatal doses. The main advantages of the present method lie in its simple, clean and reliable SPE extraction method of the six amphetamine derivatives from urine followed by their simultaneous detection and quantification by liquid chromatography with UV detection. Copyright © 2004 John Wiley & Sons, Ltd.

Hans H. Maurer - One of the best experts on this subject based on the ideXlab platform.

  • Screening for and validated quantification of amphetamines and of amphetamine- and piperazine-derived designer drugs in human blood plasma by gas chromatography/mass spectrometry.
    Journal of Mass Spectrometry, 2020
    Co-Authors: Frank T. Peters, Roland F. Staack, Simone Schaefer, Thomas Kraemer, Hans H. Maurer
    Abstract:

    The classical stimulants amphetamine, methamphetamine, ethylamphetamine and the amphetamine-derived designer drugs MDA, MDMA (‘ecstasy’), MDEA, BDB and MBDB have been widely abused for a relatively long time. In recent years, a number of newer designer drugs have entered the illicit drug market. 4-Methylthioamphetamine (MTA), p-methoxyamphetamine (PMA) and p-methoxymethamphetamine (PMMA) are also derived from amphetamine. Other designer drugs are derived from piperazine, such as benzylpiperazine (BZP), methylenedioxybenzylpiperazine (MDBP), trifluoromethylphenylpiperazine (TFMPP), m-chlorophenylpiperazine (mCPP) and p-methoxyphenylpiperazine (MeOPP). A number of severe or even fatal intoxications involving these newer substances, especially PMA, have been reported. This paper describes a method for screening for and simultaneous quantification of the above-mentioned compounds and the metabolites p-hydroxyamphetamine and p-hydroxymethamphetamine (pholedrine) in human blood plasma. The analytes were analyzed by gas chromatography/mass spectrometry in the selected-ion monitoring mode after mixed-mode solid-phase extraction (HCX) and derivatization with heptafluorobutyric anhydride. The method was fully validated according to international guidelines. It was linear from 5 to 1000 µg l−1 for all analytes. Data for accuracy and precision were within required limits with the exception of those for MDBP. The limit of quantification was 5 µg l−1 for all analytes. The applicability of the assay was proven by analysis of authentic plasma samples and of a certified reference sample. This procedure should also be suitable for confirmation of immunoassay results positive for amphetamines and/or designer drugs of the ecstasy type. Copyright © 2003 John Wiley & Sons, Ltd.

  • Studies on the metabolism and toxicological detection of the designer drug 4-Methylthioamphetamine (4-MTA) in human urine using gas chromatography-mass spectrometry.
    Journal of Chromatography B, 2005
    Co-Authors: Andreas H. Ewald, Frank T. Peters, Magdalene Weise, Hans H. Maurer
    Abstract:

    Abstract 4-Methylthioamphetamine (4-MTA) is a scheduled designer drug that has appeared on the illicit drug market and led to several non-fatal or even fatal poisonings. Only few data are available on its metabolism. The first aim of this study was to identify the 4-MTA metabolites in human urine and then to study whether the authors’ STA procedure is suitable for screening for and identification of 4-MTA and/or its metabolites in urine. After enzymatic cleavage of conjugates, solid-phase extraction (SPE) and acetylation the following metabolites could be identified by full-scan gas chromatography–mass spectrometry (GC–MS): deamino-oxo 4-MTA, deamino-hydroxy 4-MTA, ring hydroxy and β-hydroxy 4-MTA. 4-MTA sulfoxide could be identified as possible artifact. In urine samples after enzymatic hydrolysis, acidic extraction, and methylation, 4-methylthiobenzoic acid could be identified. The authors’ systematical toxicological analysis (STA) procedure using full-scan GC–MS after acid hydrolysis, liquid–liquid extraction (LLE) and acetylation allowed detection of 4-MTA as target analyte plus all the above-mentioned metabolites with the exception of 4-methylthiobenzoic acid. The extraction efficiency of 4-MTA was approximately 70% and the limit of detection (LOD) was 30 ng/ml ( S / N 3).

  • Studies on the metabolism and toxicological detection of the designer drug 4-Methylthioamphetamine (4-MTA) in human urine using gas chromatography-mass spectrometry.
    Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2005
    Co-Authors: Andreas H. Ewald, Frank T. Peters, Magdalene Weise, Hans H. Maurer
    Abstract:

    4-Methylthioamphetamine (4-MTA) is a scheduled designer drug that has appeared on the illicit drug market and led to several non-fatal or even fatal poisonings. Only few data are available on its metabolism. The first aim of this study was to identify the 4-MTA metabolites in human urine and then to study whether the authors' STA procedure is suitable for screening for and identification of 4-MTA and/or its metabolites in urine. After enzymatic cleavage of conjugates, solid-phase extraction (SPE) and acetylation the following metabolites could be identified by full-scan gas chromatography-mass spectrometry (GC-MS): deamino-oxo 4-MTA, deamino-hydroxy 4-MTA, ring hydroxy and beta-hydroxy 4-MTA. 4-MTA sulfoxide could be identified as possible artifact. In urine samples after enzymatic hydrolysis, acidic extraction, and methylation, 4-methylthiobenzoic acid could be identified. The authors' systematical toxicological analysis (STA) procedure using full-scan GC-MS after acid hydrolysis, liquid-liquid extraction (LLE) and acetylation allowed detection of 4-MTA as target analyte plus all the above-mentioned metabolites with the exception of 4-methylthiobenzoic acid. The extraction efficiency of 4-MTA was approximately 70% and the limit of detection (LOD) was 30 ng/ml (S/N 3).

  • Metabolism of designer drugs of abuse.
    Current Drug Metabolism, 2005
    Co-Authors: Roland F. Staack, Hans H. Maurer
    Abstract:

    Abstract Abuse of designer drugs is widespread among young people, especially in the so-called "dance club scene" or "rave scene", worldwide. Severe and even fatal poisonings have been attributed to the consumption of such drugs of abuse. However, in contrast to new medicaments, which are extensively studied in controlled clinical studies concerning metabolism, including cytochrome P450 isoenzyme differentiation, and further pharmacokinetics, designer drugs are consumed without any safety testing. This paper reviews the metabolism of new designer drugs of abuse that have emerged on the black market during the last years. Para-methoxyamphetamine (PMA), para-methoxymethamphetamine (PMMA) and 4-Methylthioamphetamine (4-MTA), were taken into consideration as new "classical" amphetamine-derived designer drugs. Furthermore, N-benzylpiperazine (BZP), 1-(3, 4-methylenedioxybenzyl)piperazine (MDBP), 1-(3-trifluoromethylphenyl)piperazine (TFMPP), 1-(3-chlorophenyl)piperazine (mCPP) and 1-(4-methoxyphenyl)piperazine (MeOPP) were taken into consideration as derivatives of the class of piperazine-derived designer drugs, as well as alpha-pyr-rolidinopropiophenone (PPP), 4'-methoxy-alpha-pyrrolidinopropiophenone (MOPPP), 3', 4'-methylenedioxy-alpha-pyrrolidino-propiophenone (MDPPP), 4'-methyl-alpha-pyrrolidinopropiophenone (MPPP), and 4'-methyl-alpha-pyrrolidinoexanophenone (MPHP) as derivatives of the class of alpha-pyrrolidinophenone-derived designer drugs. Papers describing identification of in vivo or in vitro human or animal metabolites and cytochrome P450 isoenzyme dependent metabolism have been considered and summarized.

J C Coumbaros - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of 4-methyl-5-arylpyrimidines and 4-arylpyrimidines: route specific markers for the Leuckardt preparation of amphetamine, 4-methoxyamphetamine, and 4-Methylthioamphetamine
    Forensic Science International, 2020
    Co-Authors: K P Kirkbride, A D Ward, N F Jenkins, G Klass, J C Coumbaros
    Abstract:

    General synthetic routes to 4-methyl-5-arylpyrimidines and 5-arylpyrimidines are described. 4-Benzylpyrimidine, 4methyl-5-phenylpyrimidine, 4-(4-methoxybenzyl)pyrimidine, and 4-methyl-5-(4-methoxyphenyl)pyrimidine have been positively identified as route-specific by-products in the Leuckardt preparations of amphetamine and 4-methoxyamphetamine. Using headspace solid phase microextraction (SPME) 4-(4-methoxybenzyl)pyrimidine and 4-methyl-5-(4-methoxyphenyl)pyrimidine have been identified in illicit tablets containing 4-methoxyamphetamine. This is an indication that illicit laboratories use the Leuckardt method for the preparation of 4-methoxyamphetamine. Flatliner tablets containing 4-Methylthioamphetamine have been screened for the presence of 4-(4-methylthiobenzyl)pyrimidine and 4-methyl-5-(4-methylthiophenyl)pyrimidine using both headspace and aqueous phase SPME. As these pyrimidines were not detected it would appear likely that illicit laboratories are not using the Leuckardt method for the preparation of 4-Methylthioamphetamine. # 2001 Elsevier Science Ireland Ltd. All rights reserved.

  • Synthesis of 4-methyl-5-arylpyrimidines and 4-arylpyrimidines: route specific markers for the Leuckardt preparation of amphetamine, 4-methoxyamphetamine, and 4-Methylthioamphetamine.
    Forensic science international, 2001
    Co-Authors: K P Kirkbride, A D Ward, N F Jenkins, G Klass, J C Coumbaros
    Abstract:

    General synthetic routes to 4-methyl-5-arylpyrimidines and 5-arylpyrimidines are described. 4-Benzylpyrimidine, 4-methyl-5-phenylpyrimidine, 4-(4-methoxybenzyl)pyrimidine, and 4-methyl-5-(4-methoxyphenyl)pyrimidine have been positively identified as route-specific by-products in the Leuckardt preparations of amphetamine and 4-methoxyamphetamine. Using headspace solid phase microextraction (SPME) 4-(4-methoxybenzyl)pyrimidine and 4-methyl-5-(4-methoxyphenyl)pyrimidine have been identified in illicit tablets containing 4-methoxyamphetamine. This is an indication that illicit laboratories use the Leuckardt method for the preparation of 4-methoxyamphetamine. Flatliner tablets containing 4-Methylthioamphetamine have been screened for the presence of 4-(4-methylthiobenzyl)pyrimidine and 4-methyl-5-(4-methylthiophenyl)pyrimidine using both headspace and aqueous phase SPME. As these pyrimidines were not detected it would appear likely that illicit laboratories are not using the Leuckardt method for the preparation of 4-Methylthioamphetamine.

Maria De Lourdes Bastos - One of the best experts on this subject based on the ideXlab platform.

  • Simultaneous determination of amphetamine derivatives in human urine after SPE extraction and HPLC-UV analysis.
    Biomedical Chromatography, 2004
    Co-Authors: Maria Elisa Soares, Helena Carmo, Fernando Remião, Félix Carvalho, Márcia Carvalho, Maria De Lourdes Bastos
    Abstract:

    Amphetamine derivatives are a class of compounds increasingly abused as recreational drugs in various regions of the world. Although d-amphetamine (AMPH) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) are among the most commonly used, the abuse of other designer drugs such as 4-bromo-2,5-dimethoxyphenethylamine (2C-B) and 4-Methylthioamphetamine (4-MTA) and their involvement in acute intoxications has been increasingly reported. There is evidence that abusers ingest these compounds either alone or in combination and the respective monitoring is important for both legal and health care purposes in hospital emergency. In the present study a simple and clean solid-phase extraction procedure from urine of AMPH and MDMA, and their major metabolites p-hydroxyamphetamine (OH-AMPH) and methylenedioxyamphetamine (MDA) and 2C-B and 4-MTA was developed. Analysis was performed by HPLC-UV and the precision of the technique was between 2.9 and 5.3% for all compounds. For the overall procedure, the precision values were between 3.3 and 5.9%. Recoveries obtained from spiked urines at three concentration levels were better than 84 ± 4% for the six compounds. The limit of detection of the method for the compounds (between 5.3 and 84.0 ng) enables their identification in urine after ingestion of fatal and non-fatal doses. The main advantages of the present method lie in its simple, clean and reliable SPE extraction method of the six amphetamine derivatives from urine followed by their simultaneous detection and quantification by liquid chromatography with UV detection. Copyright © 2004 John Wiley & Sons, Ltd.

  • Comparative metabolism of the designer drug 4-Methylthioamphetamine by hepatocytes from man, monkey, dog, rabbit, rat and mouse
    Naunyn-Schmiedeberg's Archives of Pharmacology, 2004
    Co-Authors: Helena Carmo, Franz Oesch, Douwe De Boer, Fernando Remião, Félix Carvalho, Eduarda Fernandes, Jan G. Hengstler, Michael Ringel, Lesseps A. Reys, Maria De Lourdes Bastos
    Abstract:

    Several cases of death associated with 4-Methylthioamphetamine (4-MTA) have raised public concern about the abuse of this designer drug that is usually sold as “Ecstasy” or “Flatliners”. Since only very little is known about the metabolism of 4-MTA in humans we performed an in vitro study incubating racemic 4-MTA with primary hepatocytes isolated from three male human donors. Additionally, hepatocytes from male monkey (Cynomolgus), dog (Beagle), rabbit (Chinchilla), rat (Sprague-Dawley), and mouse (CD1) were examined for the metabolism of racemic 4-MTA. We observed that 4-MTA was not extensively metabolised by hepatocytes from all species examined. The main metabolite was identified as 4-methylthiobenzoic acid which, for the first time has been described as a human metabolite. In addition to metabolism we also examined 4-MTA-induced toxicity as evidenced by the ATP cellular content. Interestingly, one of the three human donors showed a dramatically increased sensitivity to the reduction in ATP content induced by 4-MTA. Comparing the species examined, the most extensive formation of 4-methylthiobenzoic acid was observed in the rabbit hepatocytes followed by human, monkey, dog and mouse hepatocytes, whereas no formation of 4-methylthiobenzoic acid was seen in the rat hepatocytes. Toxicity data suggest that rabbit hepatocytes are more resistant to 4-MTA than the other species, which may be due to the more extensive metabolism. In conclusion, we have shown that 4-methylthiobenzoic acid is the main metabolite formed from 4-MTA by human hepatocytes and also by the hepatocytes of the other tested species except the rat. Toxicity data suggest only moderate interspecies differences.

  • 4-Methylthioamphetamine-induced hyperthermia in mice: influence of serotonergic and catecholaminergic pathways.
    Toxicology and Applied Pharmacology, 2003
    Co-Authors: Helena Carmo, Douwe De Boer, Fernando Remião, Félix Carvalho, Eduarda Fernandes, Lesseps A. Dos Reys, Maria De Lourdes Bastos
    Abstract:

    Abstract 4-Methylthioamphetamine (4-MTA), also known as p -methylthioamphetamine, is a new amphetamine derivative which in humans has been increasingly associated with severe intoxications and several deaths. As hyperthermia is considered to be one of the most life-threatening acute physiological consequences of amphetamine-related intoxications, it was our aim to determine whether 4-MTA induces changes in body temperature in a mouse model. Accordingly, we measured the subcutaneous temperature after acute administration of 4-MTA in CD1 mice. Because hyperthermia seems to result from the central and peripheral actions of catecholamines and serotonin (5-hydroxytriptamine or 5-HT), we also investigated the possible interactions of some catecholaminergic and serotonergic receptor blockers and the inhibition of monoamine oxidase (MAO) with this effect. 4-MTA induced hyperthermia in CD1 mice. Blockade of the 5-HT receptors with methysergide and MAO inhibition with pargyline resulted in the potentiation of the 4-MTA-induced hyperthermic effect. Blockade of the α 1 -adrenergic receptors with prazosin completely reverted the 4-MTA-induced hyperthermia while with the β-adrenergic receptor blocker dl -propranolol this reversal was not complete. Blockade of the α 2 -adrenergic receptors with yohimbine had no effect on the hyperthermia induced by 4-MTA. These results suggest that 4-MTA-induced hyperthermia is highly influenced by the catecholaminergic and serotonergic receptor activation and the MAO activity.

Félix Carvalho - One of the best experts on this subject based on the ideXlab platform.

  • Comparative effects of 3,4-methylenedioxymethamphetamine and 4-Methylthioamphetamine on rat liver mitochondrial function.
    Toxicology, 2010
    Co-Authors: José B A Custódio, Félix Carvalho, Eduarda Fernandes, Maria S Santos, Dália I R Gonçalves, António J M Moreno, Maria L Bastos, Joaquim A F Vicente, Maria A S Fernandes
    Abstract:

    Ecstasy, which is used as a recreational drug, is a common street name for 3, 4-methylenedioxymethamphetamine (MDMA). Another drug of abuse chemically related, though less common than MDMA, is the amphetamine derivative 4-Methylthioamphetamine (MTA). MDMA and MTA induce different systemic and organ-specific effects, including neurotoxicity, hyperthermia, nephrotoxicity, cardiotoxicity and hepatotoxicity. Therefore, it is clear that MDMA and MTA are responsible for inducing organ toxicity. The mechanisms underlying MDMA and MTA-induced hepatotoxicity are multifactorial, and therefore not completely understood. Recent findings indicate interference with cellular bioenergetics as an important toxicological feature of ecstasy. However, less is known about the involvement of mitochondria in MTA-induced hepatotoxicity. Thus, we compared the direct influence of MDMA and MTA on rat liver mitochondrial function [mitochondrial permeability transition (MPT), mitochondrial oxidative stress, and mitochondrial bioenergetics]. It was shown that MTA (from 0.025 up to 0.1mM) was more potent than MDMA (from 0.2 up to 0.5mM) in decreasing the sensitivity of rat liver mitochondria to MPT. However, higher concentrations of MTA (from 0.5 up to 2mM) were highly toxic to mitochondria. MTA simultaneously increased H(2)O(2) production in a monoamine oxidase (MAO)-dependent way, and uncoupled and inhibited mitochondrial respiration. In contrast, MDMA had only limited or no effects on these mitochondrial parameters. According to these results, it is possible to postulate that, depending on the concentration, MTA can potentially be more efficient in its effects on liver mitochondria than MDMA and, also, that its harmful effects may contribute to its hepatotoxicity.

  • CYP2D6 increases toxicity of the designer drug 4-Methylthioamphetamine (4-MTA).
    Toxicology, 2006
    Co-Authors: Helena Carmo, Marc Brulport, Matthias Hermes, Franz Oesch, Douwe De Boer, Fernando Remião, Félix Carvalho, Michael R. Schön, Niels Krebsfaenger, Johannes Doehmer
    Abstract:

    Abstract 4-Methylthioamphetamine (4-MTA) belongs to a group of new amphetamine derivatives that is usually sold as “ecstasy” or “flatliners” on the illicit drug market. Large interindividual differences in 4-MTA mediated toxicity have been reported in humans. Therefore, we tested whether CYP2D6 or its variant alleles as well as CYP3A4 influence the susceptibility to 4-MTA. For this purpose, we used the colony formation assay with Chinese hamster lung fibroblast V79 cells expressing human wild-type CYP2D6 (CYP2D6*1), the low activity alleles CYP2D6*2, CYP2D6*9, as well as human CYP3A4. The obtained results showed that the expression of wild type CYP2D6*1 clearly enhanced the susceptibility to the cytotoxic effects of 4-MTA compared with the parental cells devoid of CYP-dependent enzymatic activity. Toxicity in V79 CYP2D6*1 was also higher compared to the V79 cell lines expressing the low activity alleles CYP2D6*2 and CYP2D6*9. In contrast to CYP2D6, the CYP3A4 isoenzyme did not enhance 4-MTA toxicity. In conclusion, our results suggest that CYP2D6 rapid metabolizers may be more susceptible to 4-MTA toxicity than CYP2D6 poor metabolizers.

  • Simultaneous determination of amphetamine derivatives in human urine after SPE extraction and HPLC-UV analysis.
    Biomedical Chromatography, 2004
    Co-Authors: Maria Elisa Soares, Helena Carmo, Fernando Remião, Félix Carvalho, Márcia Carvalho, Maria De Lourdes Bastos
    Abstract:

    Amphetamine derivatives are a class of compounds increasingly abused as recreational drugs in various regions of the world. Although d-amphetamine (AMPH) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) are among the most commonly used, the abuse of other designer drugs such as 4-bromo-2,5-dimethoxyphenethylamine (2C-B) and 4-Methylthioamphetamine (4-MTA) and their involvement in acute intoxications has been increasingly reported. There is evidence that abusers ingest these compounds either alone or in combination and the respective monitoring is important for both legal and health care purposes in hospital emergency. In the present study a simple and clean solid-phase extraction procedure from urine of AMPH and MDMA, and their major metabolites p-hydroxyamphetamine (OH-AMPH) and methylenedioxyamphetamine (MDA) and 2C-B and 4-MTA was developed. Analysis was performed by HPLC-UV and the precision of the technique was between 2.9 and 5.3% for all compounds. For the overall procedure, the precision values were between 3.3 and 5.9%. Recoveries obtained from spiked urines at three concentration levels were better than 84 ± 4% for the six compounds. The limit of detection of the method for the compounds (between 5.3 and 84.0 ng) enables their identification in urine after ingestion of fatal and non-fatal doses. The main advantages of the present method lie in its simple, clean and reliable SPE extraction method of the six amphetamine derivatives from urine followed by their simultaneous detection and quantification by liquid chromatography with UV detection. Copyright © 2004 John Wiley & Sons, Ltd.

  • Comparative metabolism of the designer drug 4-Methylthioamphetamine by hepatocytes from man, monkey, dog, rabbit, rat and mouse
    Naunyn-Schmiedeberg's Archives of Pharmacology, 2004
    Co-Authors: Helena Carmo, Franz Oesch, Douwe De Boer, Fernando Remião, Félix Carvalho, Eduarda Fernandes, Jan G. Hengstler, Michael Ringel, Lesseps A. Reys, Maria De Lourdes Bastos
    Abstract:

    Several cases of death associated with 4-Methylthioamphetamine (4-MTA) have raised public concern about the abuse of this designer drug that is usually sold as “Ecstasy” or “Flatliners”. Since only very little is known about the metabolism of 4-MTA in humans we performed an in vitro study incubating racemic 4-MTA with primary hepatocytes isolated from three male human donors. Additionally, hepatocytes from male monkey (Cynomolgus), dog (Beagle), rabbit (Chinchilla), rat (Sprague-Dawley), and mouse (CD1) were examined for the metabolism of racemic 4-MTA. We observed that 4-MTA was not extensively metabolised by hepatocytes from all species examined. The main metabolite was identified as 4-methylthiobenzoic acid which, for the first time has been described as a human metabolite. In addition to metabolism we also examined 4-MTA-induced toxicity as evidenced by the ATP cellular content. Interestingly, one of the three human donors showed a dramatically increased sensitivity to the reduction in ATP content induced by 4-MTA. Comparing the species examined, the most extensive formation of 4-methylthiobenzoic acid was observed in the rabbit hepatocytes followed by human, monkey, dog and mouse hepatocytes, whereas no formation of 4-methylthiobenzoic acid was seen in the rat hepatocytes. Toxicity data suggest that rabbit hepatocytes are more resistant to 4-MTA than the other species, which may be due to the more extensive metabolism. In conclusion, we have shown that 4-methylthiobenzoic acid is the main metabolite formed from 4-MTA by human hepatocytes and also by the hepatocytes of the other tested species except the rat. Toxicity data suggest only moderate interspecies differences.

  • 4-Methylthioamphetamine-induced hyperthermia in mice: influence of serotonergic and catecholaminergic pathways.
    Toxicology and Applied Pharmacology, 2003
    Co-Authors: Helena Carmo, Douwe De Boer, Fernando Remião, Félix Carvalho, Eduarda Fernandes, Lesseps A. Dos Reys, Maria De Lourdes Bastos
    Abstract:

    Abstract 4-Methylthioamphetamine (4-MTA), also known as p -methylthioamphetamine, is a new amphetamine derivative which in humans has been increasingly associated with severe intoxications and several deaths. As hyperthermia is considered to be one of the most life-threatening acute physiological consequences of amphetamine-related intoxications, it was our aim to determine whether 4-MTA induces changes in body temperature in a mouse model. Accordingly, we measured the subcutaneous temperature after acute administration of 4-MTA in CD1 mice. Because hyperthermia seems to result from the central and peripheral actions of catecholamines and serotonin (5-hydroxytriptamine or 5-HT), we also investigated the possible interactions of some catecholaminergic and serotonergic receptor blockers and the inhibition of monoamine oxidase (MAO) with this effect. 4-MTA induced hyperthermia in CD1 mice. Blockade of the 5-HT receptors with methysergide and MAO inhibition with pargyline resulted in the potentiation of the 4-MTA-induced hyperthermic effect. Blockade of the α 1 -adrenergic receptors with prazosin completely reverted the 4-MTA-induced hyperthermia while with the β-adrenergic receptor blocker dl -propranolol this reversal was not complete. Blockade of the α 2 -adrenergic receptors with yohimbine had no effect on the hyperthermia induced by 4-MTA. These results suggest that 4-MTA-induced hyperthermia is highly influenced by the catecholaminergic and serotonergic receptor activation and the MAO activity.