Toxicokinetics and analytical toxicology of amphetamine-derived designer drugs ('Ecstasy')

Post mortem chiral analysis of MDMA and MDA in human blood and hair

Drug-related fatalities in the EU are predominantly associated with opioids. MDMA (Ecstasy) consumption results in fewer lethal intoxications despite its widespread use. This study investigates MDMA-related fatalities, focusing on enantiomer ratios of MDMA and its metabolite MDA to explore the role of metabolism in fatal outcomes. MDMA induces euphoria, increased empathy, and physiological effects such as tachycardia, hypertension, and hyperthermia. Metabolism mainly involves CYP1A2 and CYP2D6, with polymorphism of the latter influencing metabolism rates. Our institute observed several MDMA-related fatalities, which prompted an investigation into the potential role of inefficient drug metabolism in these cases. A novel quantitative chiral analysis method was developed and validated for MDMA, MDA, amphetamine and methamphetamine enantiomers in human blood. Analysis of post mortem blood samples from eleven MDMA-related fatalities exhibited a wide range of concentrations and enantiomer ratios. Variability in R/S MDMA ratios, however, could be linked to the time period of metabolism. Hair analysis revealed high MDMA concentrations in all segments, irrespective of prior drug abuse anamnesis. Therefore, hair analysis may not be suitable for the assessment of past drug use in ecstasy-related fatalities. The results indicated that elevated levels of the MDMA enantiomer are correlated with longer survival times in cases of intoxication. However, there was no clear evidence for slowed MDMA metabolism as a cause of lethal intoxications. While challenges remain due to the diversity of cases, this study contributes valuable insights into ecstasy intoxications, aiding future interpretation of post mortem analysis.

Bioisosteric analogs of MDMA: Improving the pharmacological profile?

3,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') is re-emerging in clinical settings as a candidate for the treatment of specific neuropsychiatric disorders (e.g. post-traumatic stress disorder) in combination with psychotherapy. MDMA is a psychoactive drug, typically regarded as an empathogen or entactogen, which leads to transporter-mediated monoamine release. Despite its therapeutic potential, MDMA can induce dose-, individual-, and context-dependent untoward effects outside safe settings. In this study, we investigated whether three new methylenedioxy bioisosteres of MDMA improve its off-target profile. In vitro methods included radiotracer assays, transporter electrophysiology, bioluminescence resonance energy transfer and fluorescence-based assays, pooled human liver microsome/S9 fraction incubations, metabolic stability studies, isozyme mapping, and liquid chromatography coupled to high-resolution mass spectrometry. In silico methods included molecular docking. Compared with MDMA, all three MDMA bioisosteres (ODMA, TDMA, and SeDMA) showed similar pharmacological activity at human serotonin, dopamine, and norepinephrine transporters (hSERT, hDAT, and hNET, respectively) but decreased agonist activity at 5-HT2A/2B/2C receptors. Regarding their hepatic metabolism, they differed from MDMA, with N-demethylation being the only metabolic route shared, and without forming phase II metabolites. In addition, TDMA showed an enhanced intrinsic clearance in comparison to its congeners. Additional screening for their interaction with human organic cation transporters (hOCTs) and plasma membrane monoamine transporter (hPMAT) revealed a weaker interaction of the MDMA analogs with hOCT1, hOCT2, and hPMAT. Our findings suggest that these new MDMA bioisosteres might constitute appealing therapeutic alternatives to MDMA, sparing the primary pharmacological activity at hSERT, hDAT, and hNET, but displaying a reduced activity at 5-HT2A/2B/2C receptors and alternative hepatic metabolism. Whether these MDMA bioisosteres may pose lower risk alternatives to the clinically re-emerging MDMA warrants further studies.

Balancing Therapeutic Efficacy and Safety of MDMA and Novel MDXX Analogues as Novel Treatments for Autism Spectrum Disorder

Autism spectrum disorder (ASD) encompasses a range of neurodevelopmental syndromes diagnostically characterized by deficits in social communication and social interaction and repetitive, inflexible patterns of behaviors, interests, and thoughts. ASD affects people worldwide, irrespective of race, ethnicity, or socio-economic status, with debilitating effects on employment and interpersonal relationships. Though the atypical antipsychotics aripiprazole and risperidone are approved to treat irritability associated with ASD, these drugs may elicit treatment-limiting adverse effects, such as suicidal ideation, sedation, diarrhea, loss of appetite, dizziness, and weight gain. However, there are no approved pharmacotherapeutics for global symptoms of ASD, and better treatments are needed. Drugs with pro-social effects, such as 3,4-methylenedioxymethamphetamine (MDMA) and its analogues, may be beneficial here, as social anxiety and social avoidance are major complications of ASD that adversely impact the quality of life for sufferers and caregivers. This review describes the complex pharmacology of methylenedioxy amphetamine analogues (hereafter referred to as MDXX drugs), focusing on MDMA and 3,4-methylenedioxy-N-methyl-α-ethylphenylethylamine (MBDB) and how they may help treat ASD. Specifically, we address the roles of various drug-binding sites, metabolic enzymes, and chemical structure-activity relationships that mediate these substances' pharmacological and toxicological effects. Throughout the review, we emphasize the distinct profiles of individual stereoisomers of the MDXX drugs and how combining these enantiomers as racemic mixtures may explain the complexity of drug effects on behavior and physiology. We propose that the MDXX drugs represent a fruitful chemical space for developing clinically effective and relatively safer molecules and formulations for treating ASD.

Machine Learning Models to Predict Cytochrome P450 2B6 Inhibitors and Substrates

Cytochrome P450 2B6 (CYP2B6) is responsible for the metabolism of ∼7% of marketed drugs. The in vitro drug interaction studies guidance for industry issued by the FDA stipulates that drug sponsors need to evaluate whether the investigated drugs interact with the major drug-metabolizing P450s including CYP2B6. Therefore, there has been greater attention to the development of predictive models for CYP2B6 inhibitors and substrates. In this study, conventional machine learning and deep learning models were developed to predict CYP2B6 inhibitors and substrates. Our results showed that the best CYP2B6 inhibitor model yielded the AUC values of 0.95 and 0.75 with the 10-fold cross-validation and the test set, respectively, and the best CYP2B6 substrate model produced the AUC values of 0.93 and 0.90 with the 10-fold cross-validation and the test set, respectively. The generalization ability of the CYP2B6 inhibitor and substrate models was assessed by using the external validation sets. Several significant substructural fragments relevant to CYP2B6 inhibitors and substrates were detected via frequency substructure analysis and information gain. In addition, the applicability domain of the models was defined by employing a nonparametric method based on the probability density distribution. We anticipate that our results would be useful for the prediction of potential CYP2B6 inhibitors and substrates in the early stage of drug discovery.

Analysis of 2,5-dimethoxy-amphetamines and 2,5-dimethoxy-phenethylamines aiming their determination in biological matrices: a review

PURPOSE

The present review aims to provide an overview of methods for the quantification of 2,5-dimethoxy-amphetamines and -phenethylamines in different biological matrices, both traditional and alternative ones.

METHODS

A complete literature search was carried out with PubMed, Scopus and the World Wide Web using relevant keywords, e.g., designer drugs, amphetamines, phenethylamines, and biological matrices.

RESULTS

Synthetic phenethylamines represent one of the largest classes of "designer drugs", obtained through chemical structure modifications of psychoactive substances to increase their pharmacological activities. This practice is also favored by the fact that every new synthetic compound is not considered illegal by existing legislation. Generally, in a toxicological laboratory, the first monitoring of drugs of abuse is made by rapid screening tests that sometimes can occur in false positive or false negative results. To reduce evaluation errors, it is mandatory to submit the positive samples to confirmatory methods, such as gas chromatography or liquid chromatography combined to mass spectrometry, for a more specific qualitative and quantitative analysis.

CONCLUSIONS

This review highlights the great need for updated comprehensive analytical methods, particularly when analyzing biological matrices, both traditional and alternative ones, for the search of newly emerging designer drugs.

Detection of 3,4-Methylene Dioxy Amphetamine in Urine by Magnetically Improved Surface-Enhanced Raman Scattering Sensing Strategy

Abuse of illicit drugs has become a major issue of global concern. As a synthetic amphetamine analog, 3,4-Methylene Dioxy Amphetamine (MDA) causes serotonergic neurotoxicity, posing a serious risk to human health. In this work, a two-dimensional substrate of ITO/Au is fabricated by transferring Au nanoparticle film onto indium–tin oxide glass (ITO). By magnetic inducing assembly of Fe₃O₄@Au onto ITO/Au, a sandwich-based, surface-enhanced Raman scattering (SERS) detection strategy is designed. Through the use of an external magnet, the MDA is retained in the region of hot spots formed between Fe₃O₄@Au and ITO/Au; as a result, the SERS sensitivity for MDA is superior compared to other methods, lowering the limit of detection (LOD) to 0.0685 ng/mL and attaining a corresponding linear dynamic detection range of 5–10⁵ ng/mL. As an actual application, this magnetically improved SERS sensing strategy is successfully applied to distinguish MDA in urine at trace level, which is beneficial to clinical and forensic monitors.

MDMA Intoxication in a Potential Organ Donor with Cardiac Arrest

Amphetamine and its derivatives' consumption is still an important public health issue, namely in terms of compounds variability and disposition to consumers. However, some of them, like 3,4-methylenedioxymethamphetamine (MDMA), still live in the illicit market, with continuous success. Nevertheless, there is always new information and data on MDMA intoxication, both in vivo and in postmortem context. The authors report an intoxication case with MDMA, in an 18-year-old male, considered a potential organ donor after a cardiac arrest. Whole blood samples were collected in vivo, at the emergency room (ER), and postmortem, at the National Institute of Legal Medicine and Forensic Sciences. After a general screening procedure, samples were extracted by solid phase extraction (OASIS® MCX), followed by gas chromatography-mass spectrometry analysis. The whole blood postmortem sample was positive for lidocaine (<500 ng/mL), compatible with the ER intervention, and positive for MDMA (2278 ng/mL) and methylenedioxyamphetamine (MDA) (49 ng/mL), while whole blood samples collected in vivo (during the maintenance of the individual under advanced life support), were positive for MDMA (504-1918 ng/mL) and MDA (20-89 ng/mL). Samples were negative for other substances, namely ethanol, other drugs of abuse and medicines. Results interpretation is pivotal to understand the behavior of the substance. Thus, in this case, MDMA postmortem behavior should be carefully evaluated, considering as possible influencers, in the specific context of the case, the time lapse between death verification, maintenance of the advanced life support and body manipulation for organ collection purposes. Also referred and discussed is the antemortem/postmortem ratio of MDMA obtained values, compared with literature references. There is no doubt that death was due to MDMA intoxication, but information from the analysis performed on the in vivo samples suggests that this type of sample should also be considered, in a complementary role, whenever possible.

Post-mortem distribution of the synthetic cannabinoid MDMB-CHMICA and its metabolites in a case of combined drug intoxication

This case report centres on the post-mortem distribution of the synthetic cannabinoid MDMB-CHMICA and its metabolites in the case of a 27-year-old man found dead after falling from the 24th floor of a high-rise building. Toxicological analysis of post-mortem samples confirmed, besides consumption of the synthetic cannabinoids MDMB-CHMICA (1.7 ng/mL femoral blood) and EG-018, the abuse of THC (9.3 ng/mL femoral blood), amphetamine (1050 ng/mL femoral blood), MDMA (275 ng/mL femoral blood), and cocaine. Regarding EG-018 and cocaine, only traces were detected in heart blood as well as in the brain (EG-018) and urine (cocaine), respectively, which is why no quantification was conducted in the femoral blood sample. It was concluded from femoral blood analysis that, at the time of death, the man was under the influence of the synthetic cannabinoid MDMB-CHMICA, THC, amphetamine and MDMA. Comprehensive screenings of all post-mortem specimens were conducted to elucidate the post-mortem distribution of MDMB-CHMICA and its metabolites. The MDMB-CHMICA concentrations ranged between 0.01 ng/mL (urine) and 5.5 ng/g (brain). Comparably low concentrations were detected in cardiac and femoral blood (2.1 ng/mL and 1.7 ng/mL, respectively) as well as in the psoas major muscle (1.2 ng/g). Higher concentrations were found in the lung (2.6 ng/g), liver (2.6 ng/g), and kidney (3.8 ng/g). Gastric content yielded a MDMB-CHMICA concentration of 2.4 ng/g (1.1 μg absolute). Screening for MDMB-CHMICA metabolites resulted in the detection of mainly monohydroxylated metabolites in the blood, kidney, and liver specimens. Results indicated that monohydroxylated metabolites of MDMB-CHMICA are appropriate target analytes for detecting MDMB-CHMICA intake.

Studies on Para-Methoxymethamphetamine (PMMA) Metabolite Pattern and Influence of CYP2D6 Genetics in Human Liver Microsomes and Authentic Samples from Fatal PMMA Intoxications

Para-methoxymethamphetamine (PMMA) has caused numerous fatal poisonings worldwide and appears to be more toxic than other ring-substituted amphetamines. Systemic metabolism is suggested to be important for PMMA neurotoxicity, possibly through activation of minor catechol metabolites to neurotoxic conjugates. The aim of this study was to examine the metabolism of PMMA in humans; for this purpose, we used human liver microsomes (HLMs) and blood samples from three cases of fatal PMMA intoxication. We also examined the impact of CYP2D6 genetics on PMMA metabolism by using genotyped HLMs isolated from CYP2D6 poor, population-average, and ultrarapid metabolizers. In HLMs, PMMA was metabolized mainly to 4-hydroxymethamphetamine (OH-MA), whereas low concentrations of para-methoxyamphetamine (PMA), 4-hydroxyamphetamine (OH-A), dihydroxymethamphetamine (di-OH-MA), and oxilofrine were formed. The metabolite profile in the fatal PMMA intoxications were in accordance with the HLM study, with OH-MA and PMA being the major metabolites, whereas OH-A, oxilofrine, HM-MA and HM-A were detected in low concentrations. A significant influence of CYP2D6 genetics on PMMA metabolism in HLMs was found. The catechol metabolite di-OH-MA has previously been suggested to be involved in PMMA toxicity. Our studies show that the formation of di-OH-MA from PMMA was two to seven times lower than from an equimolar dose of the less toxic drug MDMA, and do not support the hypothesis of catechol metabolites as major determinants of fatal PMMA toxicity. The present study revealed the metabolite pattern of PMMA in humans and demonstrated a great impact of CYP2D6 genetics on human PMMA metabolism.

Pooled human liver preparations, HepaRG, or HepG2 cell lines for metabolism studies of new psychoactive substances? A study using MDMA, MDBD, butylone, MDPPP, MDPV, MDPB, 5-MAPB, and 5-API as examples

Metabolism studies play an important role in clinical and forensic toxicology. Because of potential species differences in metabolism, human samples are best suitable for elucidating metabolism. However, in the case of new psychoactive substances (NPS), human samples of controlled studies are not available. Primary human hepatocytes have been described as gold standard for in vitro metabolism studies, but there are some disadvantages such as high costs, limited availability, and variability of metabolic enzymes. Therefore, the aim of our study was to investigate and compare the metabolism of six methylenedioxy derivatives (MDMA, MDBD, butylone, MDPPP, MDPV, MDPB) and two bioisosteric analogues (5-MAPB, 5-API) using pooled human liver microsomes (pHLM) combined with cytosol (pHLC) or pooled human liver S9 fraction (pS9) all after addition of co-substrates for six phase I and II reactions. In addition, HepaRG and HepG2 cell lines were used. Results of the different in vitro tools were compared to each other, to corresponding published data, and to metabolites identified in human urine after consumption of MDMA, MDPV, or 5-MAPB. Incubations with pHLM plus pHLC showed similar results as pS9. A more cost efficient model for prediction of targets for toxicological screening procedures in human urine should be identified. As expected, the incubations with HepaRG provided better results than those with HepG2 concerning number and signal abundance of the metabolites. Due to easy handling without special equipment, incubations with pooled liver preparations should be the most suitable alternative to find targets for toxicological screening procedures for methylenedioxy derivatives and bioisosteric analogues.

Impact of Cytochrome P450 2D6 Function on the Chiral Blood Plasma Pharmacokinetics of 3,4-Methylenedioxymethamphetamine (MDMA) and Its Phase I and II Metabolites in Humans

3,4-methylenedioxymethamphetamine (MDMA; ecstasy) metabolism is known to be stereoselective, with preference for S-stereoisomers. Its major metabolic step involves CYP2D6-catalyzed demethylenation to 3,4-dihydroxymethamphetamine (DHMA), followed by methylation and conjugation. Alterations in CYP2D6 genotype and/or phenotype have been associated with higher toxicity. Therefore, the impact of CYP2D6 function on the plasma pharmacokinetics of MDMA and its phase I and II metabolites was tested by comparing extensive metabolizers (EMs), intermediate metabolizers (IMs), and EMs that were pretreated with bupropion as a metabolic inhibitor in a controlled MDMA administration study. Blood plasma samples were collected from 16 healthy participants (13 EMs and three IMs) up to 24 h after MDMA administration in a double-blind, placebo-controlled, four-period, cross-over design, with subjects receiving 1 week placebo or bupropion pretreatment followed by a single placebo or MDMA (125 mg) dose. Bupropion pretreatment increased the maximum plasma concentration (C_max) and area under the plasma concentration-time curve from 0 to 24 h (AUC₂₄) of R-MDMA (9% and 25%, respectively) and S-MDMA (16% and 38%, respectively). Bupropion reduced the C_max and AUC₂₄ of the CYP2D6-dependently formed metabolite stereoisomers of DHMA 3-sulfate, DHMA 4-sulfate, and 4-hydroxy-3-methoxymethamphetamine (HMMA sulfate and HMMA glucuronide) by approximately 40%. The changes that were observed in IMs were generally comparable to bupropion-pretreated EMs. Although changes in stereoselectivity based on CYP2D6 activity were observed, these likely have low clinical relevance. Bupropion and hydroxybupropion stereoisomer pharmacokinetics were unaltered by MDMA co-administration. The present data might aid further interpretations of toxicity based on CYP2D6-dependent MDMA metabolism.

Linear pharmacokinetics of 3,4-methylenedioxypyrovalerone (MDPV) and its metabolites in the rat: relationship to pharmacodynamic effects

3,4-Methylenedioxypyrovalerone (MDPV) is a commonly abused synthetic cathinone in the United States and is associated with dangerous side effects. MDPV is a dopamine transporter blocker that is 10-fold more potent than cocaine as a locomotor stimulant in rats. Previous in vitro and in vivo metabolism studies identified 3,4-dihydroxypyrovalerone (3,4-catechol-PV) and 4-hydroxy-3-methoxypyrovalerone (4-OH-3-MeO-PV) as the two primary MDPV metabolites. This study examined MDPV pharmacokinetics and metabolism, along with associated pharmacodynamic effects in rats receiving 0.5, 1.0 and 2.0 mg/kg subcutaneous (s.c.) MDPV. Blood was collected by an indwelling jugular catheter before dosing and at 10, 20, 30, 60, 120, 240 and 480 minutes thereafter. Plasma specimens were analyzed by liquid chromatography coupled to high-resolution tandem mass spectrometry. Maximum concentrations (Cmax ) and area-under-the-curve (AUC) for MDPV and two metabolites increased proportionally with administered dose, showing linear pharmacokinetics. MDPV exhibited the highest Cmax at all doses (74.2-271.3 μg/l) and 4-OH-3-MeOH-PV the highest AUC (11 366-47 724 minutes per μg/l), being the predominant metabolite. MDPV time to Cmax (Tmax ) was 12.9-18.6 minutes, while 3,4-catechol-PV and 4-OH-3-MeO-PV peaked later with Tmax 188.6-240 minutes after s.c. dosing. Horizontal locomotor activity (HLA) and stereotypy correlated positively with plasma MDPV concentrations, while HLA correlated negatively with MDPV metabolites. These results suggest that the parent compound mediates motor stimulation after systemic MDPV administration, but additionally, metabolites may be inhibitory, may not be active or may not pass the blood brain barrier.

Chiral Plasma Pharmacokinetics of 3,4-Methylenedioxymethamphetamine and its Phase I and II Metabolites following Controlled Administration to Humans

Generally, pharmacokinetic studies on 3,4-methylenedioxymethamphetamine (MDMA) in blood have been performed after conjugate cleavage, without taking into account that phase II metabolites represent distinct chemical entities with their own effects and stereoselective pharmacokinetics. The aim of the present study was to stereoselectively investigate the pharmacokinetics of intact glucuronide and sulfate metabolites of MDMA in blood plasma after a controlled single MDMA dose. Plasma samples from 16 healthy participants receiving 125 mg of MDMA orally in a controlled study were analyzed using liquid chromatography-tandem mass spectroscopy after chiral derivatization. Pharmacokinetic parameters of R- and S-stereoisomers were determined. Sulfates of 3,4-dihydroxymethamphetamine (DHMA), and sulfate and glucuronide of 4-hydroxy-3-methoxymethamphetamine (HMMA) were identified, whereas free phase I metabolites were not detected. Stereoselective differences in Cmax and AUC24 were observed with the following preferences: R>S for MDMA and DHMA 4-sulfate; S>R for 3,4-methylenedioxyamphetamine (MDA), DHMA 3-sulfate, and HMMA glucuronide; and no preference in Cmax for HMMA sulfate. R/S ratios were >1 for all analytes after 24 hours, independent of the initial chiral preference. These are the first data on chiral pharmacokinetics of MDMA phase II metabolites in human plasma in vivo after controlled administration. The main human MDMA metabolites were shown to be sulfate and glucuronide conjugates.

Liquid chromatography-quadrupole time-of-flight mass spectrometry for screening in vitro drug metabolites in humans: investigation on seven phenethylamine-based designer drugs

Phenethylamine-based designer drugs are prevalent within the new psychoactive substance market. Characterisation of their metabolites is important in order to identify suitable biomarkers which can be used for better monitoring their consumption. Careful design of in vitro metabolism experiments using subcellular liver fractions will assist in obtaining reliable outcomes for such purposes. The objective of this study was to stepwise investigate the in vitro human metabolism of seven phenethylamine-based designer drugs using individual families of enzymes. This included para-methoxyamphetamine, para-methoxymethamphetamine, 4-methylthioamphetamine, N-methyl-benzodioxolylbutanamine, benzodioxolylbutanamine, 5-(2-aminopropyl) benzofuran and 6-(2-aminopropyl) benzofuran. Identification and structural elucidation of the metabolites was performed using liquid chromatography-quadrupole-time-of-flight mass spectrometry. The targeted drugs were mainly metabolised by cytochrome P450 enzymes via O-dealkylation as the major pathway, followed by N-dealkylation, oxidation of unsubstituted C atoms and deamination (to a small extent). These drugs were largely free from Phase II metabolism. Only a limited number of metabolites were found which was consistent with the existing literature for other phenethylamine-based drugs. Also, the metabolism of most of the targeted drugs progressed at slow rate. The reproducibility of the identified metabolites was assessed through examining formation patterns using different incubation times, substrate and enzyme concentrations. Completion of the work has led to a set of metabolites which are representative for specific detection of these drugs in intoxicated individuals and also for meaningful evaluation of their use in communities by wastewater-based drug epidemiology.

Development and application of an analytical method for curdione quantification in pregnant Sprague-Dawley rats by LC-MS/MS

The vaginal administration route suffers from relatively low absorption efficiency, which may hinder the identification of the toxicokinetics of curdione in pregnant women. A sensitive analytical method for determining the plasma concentration of curdione was developed and applied in the determination of curdione in pregnant Sprague-Dawley rats as a simulated model. Glimepiride was used as an internal standard and chromatographic separation was achieved on a Capcell Pak C18 MGIII column. A gradient elution profile with 0.5% formic acid (A)-0.5% formic acid-acetonitrile (B) was selected as mobile phase. The selected reaction monitoring mode was used for quantification based on the target fragment ions m/z 237.2 to m/z 135.1 for curdione and m/z 491.3 to m/z 352.1 for the glimepiride. The standard curve was linear over the range of 0.5-500 ng/mL for curdione in rat plasma and yielded a consistent peak pattern, even at the lower limit of quantitation of 0.5 ng/mL. The retention times of curdione and IS were 6.55 and 6.59 min, respectively. The mean recovery of curdione in rat plasma was 95.5-101.1%. The intra-day and inter-day precisions were between 2.35 and 9.08%. This LC-MS/MS method provides a simple and sensitive means for determining the plasma concentration.

Effects of 3,4-methylenedioxymethamphetamine (MDMA) and its main metabolites on cardiovascular function in conscious rats

BACKGROUND AND PURPOSE

The cardiovascular effects produced by 3,4-methylenedioxymethamphetamine (MDMA; 'Ecstasy') contribute to its acute toxicity, but the potential role of its metabolites in these cardiovascular effects is not known. Here we examined the effects of MDMA metabolites on cardiovascular function in rats.

EXPERIMENTAL APPROACH

Radiotelemetry was employed to evaluate the effects of s.c. administration of racemic MDMA and its phase I metabolites on BP, heart rate (HR) and locomotor activity in conscious male rats.

KEY RESULTS

MDMA (1-20 mg·kg(-1)) produced dose-related increases in BP, HR and activity. The peak effects on HR occurred at a lower dose than peak effects on BP or activity. The N-demethylated metabolite, 3,4-methylenedioxyamphetamine (MDA), produced effects that mimicked those of MDMA. The metabolite 3,4-dihydroxymethamphetamine (HHMA; 1-10 mg·kg(-1)) increased HR more potently and to a greater extent than MDMA, whereas 3,4-dihydroxyamphetamine (HHA) increased HR, but to a lesser extent than HHMA. Neither dihydroxy metabolite altered motor activity. The metabolites 4-hydroxy-3-methoxymethamphetamine (HMMA) and 4-hydroxy-3-methoxyamphetamine (HMA) did not affect any of the parameters measured. The tachycardia produced by MDMA and HHMA was blocked by the β-adrenoceptor antagonist propranolol.

CONCLUSIONS AND IMPLICATIONS

Our results demonstrate that HHMA may contribute significantly to the cardiovascular effects of MDMA in vivo. As such, determining the molecular mechanism of action of HHMA and the other hydroxyl metabolites of MDMA warrants further study.

Simultaneous analysis of amphetamine-type stimulants in plasma by solid-phase microextraction and gas chromatography-mass spectrometry

Brazil is considered one of the countries with the highest number of amphetamine-type stimulant (ATS) users worldwide, mainly diethylpropion (DIE) and fenproporex (FEN). The use of ATS is mostly linked to diverted prescription stimulants and this misuse is widely associated with (ab)use by drivers. A validated method was developed for the simultaneous analysis of amphetamine (AMP), DIE and FEN in plasma samples employing direct immersion-solid-phase microextraction, and gas chromatographic/mass spectrometric analysis. Trichloroacetic acid 10% was used for plasma deproteinization. In situ derivatization with propylchloroformate was employed. The linear range of the method covered from 5.0 to 100 ng/mL. The detection limits were 1.0 (AMP), 1.5 (DIE) and 2.0 ng/mL (FEN). The accuracy assessment of the control samples was within 85.58-108.33% of the target plasma concentrations. Recoveries ranged from 46.35 to 84.46% and precision was <15% of the value of relative standard deviation. This method is appropriate for screening and confirmation in plasma forensic toxicology analyses of these basic drugs.

Mixtures of 3,4-methylenedioxymethamphetamine (ecstasy) and its major human metabolites act additively to induce significant toxicity to liver cells when combined at low, non-cytotoxic concentrations

Hepatic injury after 3,4-methylenedioxymethamphetamine (MDMA; ecstasy) intoxications is highly unpredictable and does not seem to correlate with either dosage or frequency of use. The mechanisms involved include the drug metabolic bioactivation and the hyperthermic state of the liver triggered by its thermogenic action and exacerbated by the environmental circumstances of abuse at hot and crowded venues. We became interested in understanding the interaction between ecstasy and its metabolites generated in vivo as users are always exposed to mixtures of parent drug and metabolites. With this purpose, Hep G2 cells were incubated with MDMA and its main human metabolites methylenedioxyamphetamine (MDA), α-methyldopamine (α-MeDA) and N-methyl-α-methyldopamine (N-Me-α-MeDA), individually and in mixture (drugs combined in proportion to their individual EC01 ), at normal (37 °C) and hyperthermic (40.5 °C) conditions. After 48 h, viability was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Extensive concentration-response analysis was performed with single drugs and the parameters of the individual non-linear logit fits were used to predict joint effects using the well-founded models of concentration addition (CA) and independent action (IA). Experimental testing revealed that mixture effects on cell viability conformed to CA, for both temperature settings. Additionally, substantial combination effects were attained even when each substance was present at concentrations that individually produced unnoticeable effects. Hyperthermic incubations dramatically increased the toxicity of the tested drug and metabolites, both individually and combined. These outcomes suggest that MDMA metabolism has hazard implications to liver cells even when metabolites are found in low concentrations, as they contribute additively to the overall toxic effect of MDMA.

In vitro metabolism of 3,4-methylenedioxymethamphetamine in human hepatocytes

Users of the illicit drug, 3,4-methylenedioxymethamphetamine (MDMA), show signs of neurotoxicity. However, the precise mechanism of neurotoxicity caused by use of MDMA has not yet been elucidated. Synthetic glutathione (GSH) conjugates of MDMA are transported into the brain by the GSH transporter and subsequently produce neurotoxicity. The objective of this research is to show direct evidence of the formation of GSH adducts of MDMA in human hepatocytes. High-performance liquid chromatography coupled with tandem mass spectrometry was utilized to examine in vitro incubations of MDMA with cryopreserved human hepatocytes. The use of hydrophilic liquid chromatography in combination with linear ion trap mass spectrometry permitted the identification of two possible GSH metabolites. Enhanced product ion scans of m/z = 499 and 487 amu of extracts from hepatocytes treated with 1.0 mM MDMA show a distinct fragmentation pattern (m/z 194.2, 163, 135, 105), suggesting the formation of MDMA-GSH conjugate, MDMA-SG and 3,4-dihydroxymethamphetamine-SG. The formation of an MDMA-GSH conjugate was further supported by the apparent lack of the same fragmentation pattern from hepatocyte samples without MDMA treatment. The results generated from this study yield valuable qualitative and quantitative information about the neurotoxic thioether metabolites formed from MDMA in humans.

Nephrotoxic effects of designer drugs: synthetic is not better!

Designer drugs are synthetic, psychoactive substances with similar structures and activity to existing scheduled drugs or controlled chemical compounds. The use of these drugs is not generally considered illegal and they cannot be detected using standard toxicology tests--essentially they are considered to be 'legal highs'. Over the past several years, increasing numbers of designer drugs have become available. These drugs are classified as amphetamine derivatives, phenylpiperazine derivatives, synthetic cathinones, synthetic cannabinoids, phencyclidine derivatives and synthetic opioids. Although euphoria is the desired effect, neuropsychiatric and cardiac manifestations are frequently observed in individuals using these drugs at high doses or using drugs that are contaminated with other substances. Some designer drugs are also associated with adverse renal effects, including acute kidney injury from pigment nephropathy, acute tubular necrosis, obstructive nephropathy and hyponatraemia. The misuse of these drugs should be recognized and clinicians made aware of the potential for acute nephrotoxicity as the health burden of these compounds increases.

Nonlinear pharmacokinetics of (+/-)3,4-methylenedioxymethamphetamine (MDMA) and its pharmacodynamic consequences in the rat

3,4-Methylenedioxymethamphetamine (MDMA) is a widely abused illicit drug that can cause severe and even fatal adverse effects. However, interest remains for its possible clinical applications in posttraumatic stress disorder and anxiety treatment. Preclinical studies to determine MDMA's safety are needed. We evaluated MDMA's pharmacokinetics and metabolism in male rats receiving 2.5, 5, and 10 mg/kg s.c. MDMA, and the associated pharmacodynamic consequences. Blood was collected via jugular catheter at 0, 0.5, 1, 2, 4, 6, 8, 16, and 24 hours, with simultaneous serotonin (5-HT) behavioral syndrome and core temperature monitoring. Plasma specimens were analyzed for MDMA and the metabolites (±)-3,4-dihydroxymethamphetamine (HHMA), (±)-4-hydroxy-3-methoxymethamphetamine (HMMA), and (±)-3,4-methylenedioxyamphetamine (MDA) by liquid chromatography-tandem mass spectrometry. After 2.5 mg/kg MDMA, mean MDMA Cmax was 164 ± 47.1 ng/ml, HHMA and HMMA were major metabolites, and <20% of MDMA was metabolized to MDA. After 5- and 10-mg/kg doses, MDMA areas under the curve (AUCs) were 3- and 10-fold greater than those after 2.5 mg/kg; HHMA and HMMA AUC values were relatively constant across doses; and MDA AUC values were greater than dose-proportional. Our data provide decisive in vivo evidence that MDMA and MDA display nonlinear accumulation via metabolic autoinhibition in the rat. Importantly, 5-HT syndrome severity correlated with MDMA concentrations (r = 0.8083; P < 0.0001) and core temperature correlated with MDA concentrations (r = 0.7595; P < 0.0001), suggesting that MDMA's behavioral and hyperthermic effects may involve distinct mechanisms. Given key similarities between MDMA pharmacokinetics in rats and humans, data from rats can be useful when provided at clinically relevant doses.

In vitro metabolism and pharmacokinetic studies on methylone

Abuse of the stimulant designer drug methylone (methylenedioxymethcathinone) has been documented in most parts of the world. As with many of the new designer drugs that continuously appear in the illicit drug market, little is known about the pharmacokinetics of methylone. Using in vitro studies, CYP2D6 was determined to be the primary enzyme that metabolizes methylone, with minor contributions from CYP1A2, CYP2B6, and CYP2C19. The major metabolite was identified as dihydroxymethcathinone, and the minor metabolites were N-hydroxy-methylone, nor-methylone, and dihydro-methylone. Measuring the formation of the major metabolite, biphasic Michaelis-Menten kinetic parameters were determined: V(max,1) = 0.046 ± 0.005 (S.E.) nmol/min/mg protein, K(m,1) = 19.0 ± 4.2 μM, V(max,2) = 0.22 ± 0.04 nmol/min/mg protein, and K(m,2) = 1953 ± 761 μM; the low-capacity and high-affinity contribution was assigned to the activity of CYP2D6. Additionally, a time-dependent loss of CYP2D6 activity was observed when the enzyme was preincubated with methylone, reaching a maximum rate of inactivation at high methylone concentrations, indicating that methylone is a mechanism-based inhibitor of CYP2D6. The inactivation parameters were determined to be K(I) = 15.1 ± 3.4 (S.E.) μM and k(inact) = 0.075 ± 0.005 minute(-1).

Prenatal exposure to substance of abuse: a worldwide problem

Substance abuse during pregnancy is an important public health issue affecting the mother and the growing infant. Preterm labor, miscarriage, abruption and postpartum hemorrhage are obstetric complications which have been associated with women who are dependent on abused substances. Moreover, women are also at an increased risk of medical problems such as poor nutrition, anemia, urinary tract infections as well as sexually transmitted infections, hepatitis, HIV and problems related to infection. Intrauterine growth restriction, prematurity, stillbirth, neonatal abstinence syndrome, and Sudden Infant Death Syndrome represent only some of fetal effects. Later on, during childhood, it has been shown that in utero exposure to substances of abuse is associated with increased rates of respiratory infections, asthma, ear and sinus infections. Moreover, these children are more irritable, have difficulty focusing their attention, and have more behavioral problems. Therefore, the assessment of in utero exposure to abused substance is extremely necessary and is relevant for the care of the mother and the offspring. In this sense, several approaches are possible; however, recently the evaluation of in utero exposure to abused drugs has been achieved by testing biological specimens coming from fetus or newborn, pregnant or nursing mother, or from both the fetus and the mother. Maternal and neonatal biological materials reflect exposure in a specific time period and each of them has different advantages and disadvantages in terms of accuracy, time window of exposure and cost/benefit ratio. The methodology for identification and determination of abused substances in biological materials are of great importance. Consequently, sensitive and specific bioanalytical methods are necessary to accurately measure biomarkers. Different immunoassays methods are used as screening methods for drug testing in the above reported specimens, however, the results from immunoassays should be carefully interpreted and confirmed by a more specific and sensitive chromatographic methods such as GC-MS or LC-MS. The interest in the development and optimization of analytical techniques to detect abused substances in different specimens is explained by the several possibilities and information that they can provide.

Caffeine provokes adverse interactions with 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') and related psychostimulants: mechanisms and mediators

Concomitant consumption of caffeine with recreational psychostimulant drugs of abuse can provoke severe acute adverse reactions in addition to longer term consequences. The mechanisms by which caffeine increases the toxicity of psychostimulants include changes in body temperature regulation, cardiotoxicity and lowering of the seizure threshold. Caffeine also influences the stimulatory, discriminative and reinforcing effects of psychostimulant drugs. In this review, we consider our current understanding of such caffeine-related drug interactions, placing a particular emphasis on an adverse interaction between caffeine and the substituted amphetamine, 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy'), which has been most recently described and characterized. Co-administration of caffeine profoundly enhances the acute toxicity of MDMA in rats, as manifested by high core body temperature, tachycardia and increased mortality. In addition, co-administration of caffeine enhances the long-term serotonergic neurotoxicity induced by MDMA. Observations to date support an interactive model of drug-induced toxicity comprising MDMA-related enhancement of dopamine release coupled to a caffeine-mediated antagonism of adenosine receptors in addition to inhibition of PDE. These experiments are reviewed together with reports of caffeine-related drug interactions with cocaine, d-amphetamine and ephedrine where similar mechanisms are implicated. Understanding the underlying mechanisms will guide appropriate intervention strategies for the management of severe reactions and potential for increased drug-related toxicity, resulting from concomitant caffeine consumption.

Toxicity of amphetamines: an update

Amphetamines represent a class of psychotropic compounds, widely abused for their stimulant, euphoric, anorectic, and, in some cases, emphathogenic, entactogenic, and hallucinogenic properties. These compounds derive from the β-phenylethylamine core structure and are kinetically and dynamically characterized by easily crossing the blood-brain barrier, to resist brain biotransformation and to release monoamine neurotransmitters from nerve endings. Although amphetamines are widely acknowledged as synthetic drugs, of which amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) are well-known examples, humans have used natural amphetamines for several millenniums, through the consumption of amphetamines produced in plants, namely cathinone (khat), obtained from the plant Catha edulis and ephedrine, obtained from various plants in the genus Ephedra. More recently, a wave of new amphetamines has emerged in the market, mainly constituted of cathinone derivatives, including mephedrone, methylone, methedrone, and buthylone, among others. Although intoxications by amphetamines continue to be common causes of emergency department and hospital admissions, it is frequent to find the sophism that amphetamine derivatives, namely those appearing more recently, are relatively safe. However, human intoxications by these drugs are increasingly being reported, with similar patterns compared to those previously seen with classical amphetamines. That is not surprising, considering the similar structures and mechanisms of action among the different amphetamines, conferring similar toxicokinetic and toxicological profiles to these compounds. The aim of the present review is to give an insight into the pharmacokinetics, general mechanisms of biological and toxicological actions, and the main target organs for the toxicity of amphetamines. Although there is still scarce knowledge from novel amphetamines to draw mechanistic insights, the long-studied classical amphetamines-amphetamine itself, as well as methamphetamine and MDMA, provide plenty of data that may be useful to predict toxicological outcome to improvident abusers and are for that reason the main focus of this review.

Lost in translation: preclinical studies on 3,4-methylenedioxymethamphetamine provide information on mechanisms of action, but do not allow accurate prediction of adverse events in humans

3,4-Methylenedioxymethamphetamine (MDMA) induces both acute adverse effects and long-term neurotoxic loss of brain 5-HT neurones in laboratory animals. However, when choosing doses, most preclinical studies have paid little attention to the pharmacokinetics of the drug in humans or animals. The recreational use of MDMA and current clinical investigations of the drug for therapeutic purposes demand better translational pharmacology to allow accurate risk assessment of its ability to induce adverse events. Recent pharmacokinetic studies on MDMA in animals and humans are reviewed and indicate that the risks following MDMA ingestion should be re-evaluated. Acute behavioural and body temperature changes result from rapid MDMA-induced monoamine release, whereas long-term neurotoxicity is primarily caused by metabolites of the drug. Therefore acute physiological changes in humans are fairly accurately mimicked in animals by appropriate dosing, although allometric dosing calculations have little value. Long-term changes require MDMA to be metabolized in a similar manner in experimental animals and humans. However, the rate of metabolism of MDMA and its major metabolites is slower in humans than rats or monkeys, potentially allowing endogenous neuroprotective mechanisms to function in a species specific manner. Furthermore acute hyperthermia in humans probably limits the chance of recreational users ingesting sufficient MDMA to produce neurotoxicity, unlike in the rat. MDMA also inhibits the major enzyme responsible for its metabolism in humans thereby also assisting in preventing neurotoxicity. These observations question whether MDMA alone produces long-term 5-HT neurotoxicity in human brain, although when taken in combination with other recreational drugs it may induce neurotoxicity.

Investigations on the stereoselectivity of the phase II metabolism of the 3,4-methylenedioxyethylamphetamine (MDEA) metabolites 3,4-dihydroxyethylamphetamine (DHEA) and 4-hydroxy-3-methoxyethylamphetamine (HMEA)

Different elimination was reported for the two enantiomers of the designer drug 3,4-methylenedioxyethylamphetamine (MDEA) in vivo. In the present work, the enantioselectivity of glucuronidation and sulfation of the MDEA phase I metabolites 3,4-dihydroxyethylamphetamine (DHEA) and 4-hydroxy-3-methoxyethylamphetamine (HMEA) was investigated. First, glucuronide standards were synthesized using rat liver microsomes. Incubations were performed with recombinant human UDP-glucuronyltransferases (UGT) and pooled human liver microsomes (pHLM) for glucuronidation and using recombinant human sulfotransferases (SULT) and pooled human liver cytosol (pHLC) for sulfation. Product formation experiments were performed by quantification of the phase II metabolites using liquid chromatography-high-resolution mass spectrometry. Additionally, substrate depletion experiments were conducted by gas chromatography-mass spectrometry after chiral derivatization for sulfation. UGT2B7, 2B15, and 2B17 were involved in glucuronidation of HMEA and SULT1A1 and SULT1A3 and SULT1A3 and SULT1E1 in the sulfation of DHEA and HMEA, respectively. SULTs provided much higher affinity, whereas UGTs showed higher capacities. Marked stereoselectivity could be observed for UGT2B15, UGT2B17, and pHLM toward S-HMEA, for SULT1A3 and pHLC toward S-DHEA and for SULT1A3 and pHLC toward R-HMEA. In conclusion, the phase II metabolism might also contribute to the observed different pharmacokinetic properties of MDEA.

Molecularly imprinted solid-phase extraction for the selective determination of methamphetamine, amphetamine, and methylenedioxyphenylalkylamine designer drugs in human whole blood by gas chromatography-mass spectrometry

A novel method is described for the extraction of methamphetamine, amphetamine, and methylenedioxyphenylalkylamine designer drugs, such as 3,4-methylenedioxy-methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxyethylamphetamine, N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine, and 3,4-(methylenedioxyphenyl)-2-butanamine, from human whole blood using molecularly imprinted solid-phase extraction as highly selective sample clean-up technique. Whole blood samples were diluted with 10 mmol/L ammonium acetate (pH 8.6) and applied to a SupelMIP-Amphetamine molecularly imprinted solid-phase extraction cartridge. The cartridge was then washed to eliminate interferences, and the amphetamines of interest were eluted with formic acid/methanol (1:100, v/v). After derivatization with trifluoroacetic anhydride, the analytes were quantified using gas chromatography-mass spectrometry. Recoveries of the seven amphetamines spiked into whole blood were 89.1-102%. The limits of quantification for each compound in 200 μL of whole blood were between 0.25 and 1.0 ng. The maximum intra- and inter-day coefficients of variation were 9.96 and 13.8%, respectively. The results show that methamphetamine, amphetamine, and methylenedioxyphenylalkyl-amine designer drugs can be efficiently extracted from crude biological samples such as whole blood by molecularly imprinted solid-phase extraction with good reproducibility. This extraction method will be useful for the pretreatment of human samples before gas chromatography-mass spectrometry.

Urinary excretion kinetics of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) and its phase I and phase II metabolites in humans following controlled MDMA administration

BACKGROUND

3,4-Methylendioxymethamphetamine (MDMA) is excreted inhuman urine as unchanged drug and phase I and II metabolites. Previous urinary excretion studies after controlled oral MDMA administration have been performed only after conjugate cleavage. Therefore, we investigated intact MDMA glucuronide and sulfate metabolite excretion.

METHODS

We used LC-high-resolution MS and GC-MS to reanalyze blind urine samples from 10 participants receiving 1.0 or 1.6 mg/kg MDMA orally. We determined median C(max),t(max), first and last detection times, and total urinary recovery; calculated ratios of sulfates and glucuronides; and performed in vitro-in vivo correlations.

RESULTS

Phase II metabolites of 3,4-dihydroxymethamphetamine (DHMA),4-hydroxy-3-methoxymethamphetamine (HMMA),3,4-dihydroxyamphetamine (DHA), and 4-hydroxy-3-methoxyamphetamine were identified, although only DHMA sulfates, HMMA sulfate, and HMMA glucuronide had substantial abundance. Good correlation was observed for HMMA measured after acid hydrolysis and the sum of unconjugated HMMA, HMMA glucuronide, and HMMA sulfate (R(2) = 0.87). More than 90% of total DHMA and HMMA were excreted as conjugates. The analyte with the longest detection time was HMMA sulfate. Median HMMA sulfate/glucuronide and DHMA 3-sulfate/4-sulfate ratios for the first 24 h were 2.0 and 5.3, respectively, in accordance with previous in vitro calculations from human liver microsomes and cytosol experiments.

CONCLUSIONS

Human MDMA urinary metabolites are primarily sulfates and glucuronides,with sulfates present in higher concentrations than glucuronides. This new knowledge may lead to improvements in urine MDMA and metabolite analysis in clinical and forensic toxicology, particularly for the performance of direct urine analysis.

Investigation on the enantioselectivity of the sulfation of the methylenedioxymethamphetamine metabolites 3,4-dihydroxymethamphetamine and 4-hydroxy-3-methoxymethamphetamine using the substrate-depletion approach

Different pharmacokinetic properties are known for the two enantiomers of the entactogen 3,4-methylendioxy-methamphetamine (MDMA), most likely due to enantioselective metabolism. The aim of the present work was 1) the investigation of the main sulfotransferases (SULT) isoenzymes involved in the sulfation of the main MDMA phase I metabolites 3,4-dihydroxymethamphetamine (DHMA) and 4-hydroxy-3-methoxymethamphetamine (HMMA) and 2) the evaluation of a possible enantioselectivity of this phase II metabolic step. Therefore, racemic DHMA and HMMA were incubated with heterologously expressed SULTs, and quantification of the sulfates by liquid chromatography-high-resolution mass spectrometry was conducted. Because separation of DHMA and HMMA sulfate could not be achieved by liquid chromatography, enantioselective kinetic parameters were determined using the substrate-depletion approach with enantioselective quantification of substrate consumption by gas chromatography-negative ion chemical ionization mass spectrometry. SULT1A1 and SULT1A3 catalyzed sulfation of DHMA, and SULT1A3 and SULT1E1 catalyzed sulfation of HMMA. SULT1A1 and SULT1E1 revealed classic Michaelis-Menten kinetics, whereas SULT1A3 kinetics showed deviation from the typical Michaelis-Menten kinetics, resulting in a concentration-dependent self-inhibition. SULT1A3 showed the highest affinity and capacity of the SULT isoforms. Marked enantioselectivity could be observed for S-DHMA sulfation by SULT1A3 and in human liver cytosol, whereas no differences were observed for HMMA sulfation. Finally, comparison of K(m) and V(max) values calculated using achiral product formation and chiral substrate depletion showed good correlation within 2-fold of each other. In conclusion, preferences for S-enantiomers were observed for DHMA sulfation, but not for HMMA sulfation.

Stereoselective urinary MDMA (ecstasy) and metabolites excretion kinetics following controlled MDMA administration to humans

The R- and S-enantiomers of racemic 3,4-methylenedioxymethamphetamine (MDMA) exhibit different dose-concentration curves. In plasma, S-MDMA was eliminated at a higher rate, most likely due to stereoselective metabolism. Similar data were shown in various in vitro experiments. The aim of the present study was the in vivo investigation of stereoselective elimination of MDMA's phase I and phase II metabolites in human urine following controlled oral MDMA administration. Urine samples from 10 participants receiving 1.0 and 1.6 mg/kg MDMA separated by at least one week were analyzed blind by liquid chromatography-high resolution-mass spectrometry and gas chromatography-mass spectrometry after chiral derivatization with S-heptafluorobutyrylprolyl chloride. R/S ratios at C(max) were comparable after low and high doses with ratios >1 for MDMA, free DHMA, and HMMA sulfate, and with ratios <1 for MDA, free HMMA, DHMA sulfate and HMMA glucuronide. In the five days after the high MDMA dose, a median of 21% of all evaluated compounds were excreted as R-stereoisomers and 17% as S-stereoisomers. Significantly greater MDMA, DHMA, and HMMA sulfate R-enantiomers and HMMA and HMMA glucuronide S-stereoisomers were excreted. No significant differences were observed for MDA and DHMA sulfate stereoisomers. Changes in R/S ratios could be observed over time for all analytes, with steady increases in the first 48 h. R/S ratios could help to roughly estimate time of MDMA ingestion and therefore, improve interpretation of MDMA and metabolite urinary concentrations in clinical and forensic toxicology.

Development and validation of LC-HRMS and GC-NICI-MS methods for stereoselective determination of MDMA and its phase I and II metabolites in human urine

3,4-Methylenedioxymethamphetamine (MDMA) is a racemic drug of abuse and its R- and S-enantiomers are known to differ in their dose-response curve. The S-enantiomer was shown to be eliminated at a higher rate than the R-enantiomer most likely explained by stereoselective metabolism that was observed in various in vitro experiments. The aim of this work was the development and validation of methods for evaluating the stereoselective elimination of phase I and particularly phase II metabolites of MDMA in human urine. Urine samples were divided into three different methods. Method A allowed stereoselective determination of the 4-hydroxy-3-methoxymethamphetamine (HMMA) glucuronides and only achiral determination of the intact sulfate conjugates of HMMA and 3,4-dihydroxymethamphetamine (DHMA) after C18 solid-phase extraction by liquid chromatography-high-resolution mass spectrometry with electrospray ionization. Method B allowed the determination of the enantiomer ratios of DHMA and HMMA sulfate conjugates after selective enzymatic cleavage and chiral analysis of the corresponding deconjugated metabolites after chiral derivatization with S-heptafluorobutyrylprolyl chloride using gas chromatography-mass spectrometry with negative-ion chemical ionization. Method C allowed the chiral determination of MDMA and its unconjugated metabolites using method B without sulfate cleavage. The validation process including specificity, recovery, matrix effects, process efficiency, accuracy and precision, stabilities and limits of quantification and detection showed that all methods were selective, sensitive, accurate and precise for all tested analytes.

Efflux transporters- and cytochrome P-450-mediated interactions between drugs of abuse and antiretrovirals

Multidrug regimens and corresponding drug interactions cause many adverse reactions and treatment failures. Drug efflux transporters: P-gp, MRP, BCRP in conjunction with metabolizing enzymes (CYPs) are major factors in such interactions. Most effective combination antiretrovirals (ARV) therapy includes a PI or a NNRTI or two NRTI. Coadministration of such ARV may induce efflux transporters and/or CYP3A4 resulting in sub-therapeutic blood levels and therapeutic failure due to reduced absorption and/or increased metabolism. A similar prognosis is true for ARV-compounds and drugs of abuse combinations. Morphine and nicotine enhance CYP3A4 and MDR1 expression in vitro. A 2.5 fold rise of cortisol metabolite was evident in smokers relative to nonsmokers. Altered functions of efflux transporters and CYPs in response to ARV and drugs of abuse may result in altered drug absorption and metabolism. Appropriate in vitro models can be employed to predict such interactions. Influence of genetic polymorphism, SNP and inter-individual variation in drug response has been discussed. Complexity underlying the relationship between efflux transporters and CYP makes it difficult to predict the outcome of HAART as such, particularly when HIV patients taking drugs of abuse do not adhere to HAART regimens. HIV(+) pregnant women on HAART medications, indulging in drugs of abuse, may develop higher viral load due to such interactions and lead to increase in mother to child transmission of HIV. A multidisciplinary approach with clear understanding of mechanism of interactions may allow proper selection of regimens so that desired therapeutic outcome of HAART can be reached without any side effects.

Effect of 3,4-methylenedioxyamphetamine on dendritic spine dynamics in rat neocortical neurons--involvement of heat shock protein 27

Along with chronic neurotoxic effects, the long-term consumption of amphetamines has been associated to psychiatric symptoms and memory disturbances. Dendritic spine dynamics have been discussed as a possible morphological correlate. However, the underlying mechanisms are still elusive. 3,4-Methylenedioxyamphetamine (MDA), a major drug of abuse and a main metabolite after 3,4-methylenedioxymethamphetamine (MDMA) intake, provokes a loss of dendritic spine-like protrusions in primary cultures of rat cortical neurons. 3,4-Methylenedioxyamphetamine also induced a rapid activation of the p38 mitogen activated protein kinase (p38 MAPK) pathway and phosphorylation of heat shock protein 27 (hsp27) indicative for its decreased chaperone activity. Concurrent pharmacological inhibition of the p38 MAPK by SB203580 abolished hsp27 phosphorylation and diminished the loss of dendritic spine-like protrusions. Moreover, upon MDA treatment dendritic spine-like protrusions were stabilized in neurons constitutively expressing hsp27. In parallel experiments we observed a robust activation of the heat shock transcription factor 1 (HSF-1) and a subsequent increase of hsp27 and hsp70. The regulation of small heat shock proteins corroborates the existence of a neuronal stress response after MDA treatment. Pharmacological targeting of small heat shock protein phosphorylation may provide a new strategy to preserve spine integrity after amphetamine exposure.

Mother-to-child transmission (MTCT) of HIV and drugs of abuse in post-highly active antiretroviral therapy (HAART) era

In the pre-highly active antiretroviral therapy (HAART) era, prenatal "vertical" mother-to-child transmission (MTCT) of HIV was about 25% and exposure of pregnant mothers to drugs of abuse (illicit drugs and tobacco smoking) was a significant contributory factor of MTCT. However, with the introduction of HAART, the rate of MTCT of HIV has decreased to less that 2%. But, it is estimated that currently about 5.1% of pregnant women use illicit drugs and 16.4% smoke tobacco. The residual prevalence of MTCT is of concern and may be related to this continued prevalence of substance use among pregnant mothers. In this report, we review and present evidence that supports the hypothesis that drugs of abuse do have the potential to increase MTCT of HIV in the presence of HAART. Exposure to drugs of abuse during pregnancy may increase MTCT of HIV through a variety of mechanisms that are addressed in detail including possible damage to the placenta, induction of preterm birth, and increasing maternal plasma viral load though a variety of putative mechanisms such as: (a) promoting HIV replication in monocyte/macrophages; (b) increasing the expression of CCR5 receptors; (c) decreasing the expression of CCR5 receptor ligands; (d) increasing the expression of CXCR4 receptors; (e) increasing the expression of DC-SIGN; (f) impairing the efficacy of HAART through drug-drug interaction; and (g) promoting HIV mutation and replication through non-adherence to HAART.

3,4-Methylenedioxymethamphetamine alters left ventricular function and activates nuclear factor-Kappa B (NF-κB) in a time and dose dependent manner

3,4-Methylenedioxymethamphetamine (MDMA) is an illicit psychoactive drug with cardiovascular effects that have not been fully described. In the current study, we observed the effects of acute MDMA on rabbit left ventricular function. We also observed the effects of MDMA on nuclear factor-kappa B (NF-κB) activity in cultured rat ventricular myocytes (H9c2). In the rabbit, MDMA (2 mg/kg) alone caused a significant increase in heart rate and a significant decrease in the duration of the cardiac cycle. Inhibition of nitric oxide synthase (NOS) by pretreatment with L-NAME (10 mg/kg) alone caused significant dysfunction in heart rate, systolic pressure, diastolic pressure, duration of relaxation, duration of cardiac cycle, and mean left ventricular pressure. Pretreatment with L-NAME followed by treatment with MDMA caused significant dysfunction in additional parameters that were not abnormal upon exposure to either compound in isolation: duration of contraction, inotropy, and pulse pressure. Exposure to 1.0 mM MDMA for 6 h or 2.0 μM MDMA for 12 h caused increased nuclear localization of NF-κB in cultured H9c2 cells. The current results suggest that MDMA is acutely detrimental to heart function and that an intact cardiovascular NOS system is important to help mitigate early sequelae in some functional parameters. The delayed timing of NF-κB activation suggests that this factor may be relevant to MDMA induced cardiomyopathy of later onset.

Mechanisms mediating the ability of caffeine to influence MDMA ('Ecstasy')-induced hyperthermia in rats

BACKGROUND AND PURPOSE

Caffeine exacerbates the hyperthermia associated with an acute exposure to 3,4 methylenedioxymethamphetamine (MDMA, 'Ecstasy') in rats. The present study investigated the mechanisms mediating this interaction.

EXPERIMENTAL APPROACH

Adult male Sprague-Dawley rats were treated with caffeine (10 mg x kg(-1); i.p.) and MDMA (15 mg x kg(-1); i.p.) alone and in combination. Core body temperatures were monitored before and after drug administration.

KEY RESULTS

Central catecholamine depletion blocked MDMA-induced hyperthermia and its exacerbation by caffeine. Caffeine provoked a hyperthermic response when the catecholamine releaser d-amphetamine (1 mg x kg(-1)) was combined with the 5-HT releaser D-fenfluramine (5 mg x kg(-1)) or the non-selective dopamine receptor agonist apomorphine (1 mg x kg(-1)) was combined with the 5-HT(2) receptor agonist DOI (2 mg x kg(-1)) but not following either agents alone. Pretreatment with the dopamine D(1) receptor antagonist Schering (SCH) 23390 (1 mg x kg(-1)), the 5-HT(2) receptor antagonist ketanserin (5 mg x kg(-1)) or alpha(1)-adreno- receptor antagonist prazosin (0.2 mg x kg(-1)) blocked MDMA-induced hyperthermia and its exacerbation by caffeine. Co-administration of a combination of MDMA with the PDE-4 inhibitor rolipram (0.025 mg x kg(-1)) and the adenosine A(1/2) receptor antagonist 9-chloro-2-(2-furanyl)-[1,2,4]triazolo[1,5-C]quinazolin-5-amine 15943 (10 mg x kg(-1)) or the A(2A) receptor antagonist SCH 58261 (2 mg x kg(-1)) but not the A(1) receptor antagonist DPCPX (10 mg x kg(-1)) exacerbated MDMA-induced hyperthermia.

CONCLUSIONS AND IMPLICATIONS

A mechanism comprising 5-HT and catecholamines is proposed to mediate MDMA-induced hyperthermia. A combination of adenosine A(2A) receptor antagonism and PDE inhibition can account for the exacerbation of MDMA-induced hyperthermia by caffeine.