Pharmacological interaction between 3,4-methylenedioxymethamphetamine (ecstasy) and paroxetine: pharmacological effects and pharmacokinetics.

3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") is increasingly used by young people for its euphoric and empathic effects. MDMA can be used in combination with other drugs such as selective serotonin reuptake inhibitors. A clinical trial was designed where subjects pretreated with paroxetine, one of the most potent inhibitors of both 5-hydroxytryptamine reuptake and CYP2D6 activity, were challenged with a single dose of MDMA. The aim of the study was to evaluate the pharmacodynamic and pharmacokinetic interaction between paroxetine and MDMA in humans. A randomized, double-blind, crossover, placebo-controlled trial was conducted in 12 healthy male subjects. Variables included physiological parameters, psychomotor performance, subjective effects, and pharmacokinetics. Subjects received 20 mg/day paroxetine (or placebo) orally for the 3 days before MDMA challenge (100 mg oral). MDMA alone produced the prototypical effects of the drug. Pretreatment with paroxetine was associated with marked decreases of both physiological and subjective effects of MDMA, despite a 30% increase in MDMA plasma concentrations. The decreases of 3-methoxy-4-hydroxymethamphetamine plasma concentrations suggest a metabolic interaction of paroxetine and MDMA. These data show that pretreatment with paroxetine significantly attenuates MDMA-related physiological and psychological effects. It seems that paroxetine could interact with MDMA at pharmacodynamic (serotonin transporter) and pharmacokinetic (CYP2D6 metabolism) levels. Marked decrease in the effects of MDMA could lead users to take higher doses of MDMA and to produce potential life-threatening toxic effects.

Contribution of cytochrome P450 2D6 to 3,4-methylenedioxymethamphetamine disposition in humans: use of paroxetine as a metabolic inhibitor probe.

BACKGROUND: 3,4-Methylenedioxymethamphetamine (MDMA) is a synthetic amphetamine derivative typically used for recreational purposes. The participation of cytochrome P450 (CYP) 2D6 in the oxidative metabolism of MDMA may suggest an increased risk of acute toxicity in CYP2D6 poor metabolisers. This study was aimed at assessing the contribution of CYP2D6 to MDMA disposition in vivo using paroxetine as a metabolic probe inhibitor. Paroxetine, a CYP2D6 inhibitor, was repeatedly administered before MDMA administration. STUDY DESIGN: This was a randomised, double-blind, crossover, placebo-controlled trial conducted in seven healthy male volunteers who were CYP2D6 extensive metabolisers. Treatment conditions (paroxetine/MDMA and placebo/MDMA) were randomly assigned. Each volunteer participated in two 3-day sessions. On days 1, 2 and 3 subjects received a single oral dose of paroxetine or placebo 20 mg. On the third day, a single oral dose of MDMA 100 mg was administered in both paroxetine and placebo conditions. METHODS: Plasma concentration-time profiles and urinary recoveries of MDMA and its metabolites were measured, as well as plasma concentrations of paroxetine, (3S,4R)-4-(4-fluorophenyl)-3-(3,4-methylenedioxyphenoxymethyl)-piperidine, and (3S,4R)-4-(4-fluorophenyl)-3-(3-methoxy-4-hydroxyphenoxymethyl)-piperidine (HM-paroxetine). RESULTS: Paroxetine given before MDMA resulted in significant increases of MDMA area under the plasma concentration-time curve from 0 to 27 hours (AUC(27)) [23%], AUC from zero to infinity (AUC(infinity)) [27%] and maximum plasma concentration (C(max)) [17%], without significant differences in MDMA time to reach C(max) (t(max)). MDMA elimination-related pharmacokinetic parameters showed a significant reduction of MDMA elimination rate constant (K(e)) [-14%] and plasmatic clearance (CL(P)) [-29%]. In the case of 3,4-dihydroxymethamphetamine (HHMA), a 21% decrease in C(max) with no significant differences in AUC(27), AUC(infinity), K(e) and elimination half-life) were found. 4-Hydroxy-3-methoxymethamphetamine (HMMA) showed a decrease in plasma concentrations with a reduction in AUC(27) (-28%), AUC(infinity) (-20%) and C(max) (-46%). In the case of 3,4-methylenedioxyamphetamine (MDA) an increase in C(max) (17%) and AUC(27) (16%) was found. Following paroxetine pretreatment, the urinary recovery (0-45 hours) of MDMA increased by 11%; HHMA and HMMA urinary recoveries were 27% and 16% lower, respectively compared with placebo. The ratio of C(max) values of paroxetine and its metabolite on days 1 and 3 showed a 3-fold reduction, with no differences in t(max). DISCUSSION AND CONCLUSION: The contribution of CYP2D6 to MDMA metabolism in humans is not >30%, therefore other CYP isoenzymes may contribute to O-demethylenation of MDMA. Accordingly, the relevance of genetic polymorphism in CYP2D6 activity on MDMA effects and MDMA-induced acute toxicity should be examined as well as the interactions of other CYP2D6 substrates with MDMA, once the enzyme is inhibited. The pharmacokinetics of HM-paroxetine in humans after the administration of repeated doses is reported for the first time in this study.

Stereochemical analysis of 3,4-methylenedioxymethamphetamine and its main metabolites in human samples including the catechol-type metabolite (3,4-dihydroxymethamphetamine).

3,4-Methylenedioxymethamphetamine (MDMA; "ecstasy") is a designer drug commonly misused in large segments of young populations. MDMA is usually formulated in tablets of its racemate (1:1 mixture of its enantiomers) in doses ranging from 50 to 200 mg. MDMA has an enantioselective metabolism, the (S)-enantiomer being metabolized faster than the (R)-enantiomer. Different pharmacologic properties have been attributed to each enantiomer. The carbon responsible for MDMA chirality is preserved along its metabolic disposition. An analytical method has been developed to determine MDMA enantiomers and those from its major metabolites, 3,4-methylenedioxyamphetamine (MDA), 3,4-dihydroxymeth-amphetamine (HHMA), and 4-hydroxy-3-methoxymethamphet-amine (HMMA). It has been applied to the analysis of plasma and urine samples from healthy recreational users of MDMA who participated voluntarily in a clinical trial and received 100 mg (R,S)-MDMA. HCl orally. (R)/(S) ratios both in plasma (0-48 h) and urine (0-72 h) for MDMA and MDA were >1 and <1, respectively. Ratios corresponding to HHMA and HMMA, close to unity, deviate from theoretical expectations and are most likely explained by the ability of MDMA to autoinhibit its own metabolism. The short elimination half-life of (S)-MDMA (4.8 h) is consistent with the subjective effects and psychomotor performance reported in subjects exposed to MDMA, whereas the much longer half-life of the (R)-enantiomer (14.8 h) correlates with mood and cognitive effects experienced on the next days after MDMA use.

Human pharmacology of MDMA: pharmacokinetics, metabolism, and disposition.

MDMA (3,4-methylenedioxymethamphetamine, ecstasy) is a widely misused psychostimulant drug abused among large segments of the young population. Pharmacologically it displays effects related to amphetamine-type drugs and a set of distinctive effects (closeness to others, facilitation to interpersonal relationship, and empathy) that have been named by some authors "entactogen" properties. MDMA is a potent releaser and/or reuptake inhibitor of presynaptic serotonin (5-HT), dopamine (DA), and norepinephrine (NE). These actions result from the interaction of MDMA with the membrane transporters involved in neurotransmitter reuptake and vesicular storage systems. The most frequent effects after MDMA/ecstasy administration are euphoria, well-being, happiness, stimulation, increased energy, extroversion, feeling close to others, increased empathy, increased sociability, enhanced mood, mild perceptual disturbances, changed perception of colors and sounds, somatic symptoms related to its cardiovascular and autonomic effects (blood pressure and heart rate increase, mydriasis), and moderate derealization but not hallucinations. Acute toxic effects are related to its pharmacologic actions. The serotonin syndrome (increased muscle rigidity, hyperreflexia, and hyperthermia), among others, is characteristic of acute toxicity episodes. MDMA metabolism is rather complex and includes 2 main metabolic pathways: (1) O-demethylenation followed by catechol-O-methyltransferase (COMT)-catalyzed methylation and/or glucuronide/sulfate conjugation; and (2) N-dealkylation, deamination, and oxidation to the corresponding benzoic acid derivatives conjugated with glycine. The fact that the polymorphic enzyme CYP2D6 partially regulates the O-demethylenation pathway prompted some expectations that subjects displaying the poor metabolizer phenotype may be at higher risk of acute toxicity episodes. In this metabolic pathway a mechanism-based inhibition of the enzyme operates because the formation of an enzyme-metabolite complex that renders all subjects, independently of genotype, phenotypically poor metabolizers after the administration of 2 consecutive doses. Therefore, the impact of CYP2D6 pharmacogenetics on acute toxicity is limited. One of the interesting features of MDMA metabolism is its potential involvement in the development of mid- to long-term neurotoxic effects as a result of progressive neurodegeneration of the serotonergic neurotransmission system.

Paroxetine inhibits acute effects of 3,4-methylenedioxymethamphetamine on the immune system in humans.

The effect of pretreatment with paroxetine on cell-mediated immune response and release of cytokines after the administration of 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") was investigated in a double-blind, randomized, crossover, controlled clinical trial in which 12 healthy male recreational users of MDMA participated. Subjects received 20 mg/day paroxetine (or placebo) for the 3 days before MDMA challenge (100 mg). Acute MDMA administration produced a time-dependent decrease in CD4 T-helper cells, a decrease in the functional responsiveness of lymphocytes to mitogenic stimulation, a simultaneous increase in natural killer (NK) cells as well as cortisol and prolactin stimulation kinetics. A high increase in the release of anti-inflammatory cytokines (transforming growth factor-beta and interleukin-10) with a simultaneous decrease of anti-inflammatory response (interleukin-2) was also observed. Pretreatment with paroxetine partially reduced MDMA effects on CD4 T and NK cells, whereas totally inhibiting the suppression of the immune response to mitogens and alterations in cytokines release. MDMA-induced alterations in the immune system as well as antagonistic effects mediated by paroxetine show a trend toward baseline levels at 24 h. These findings suggest that acute effects of MDMA on immune system are mainly mediated by its interaction with the serotonin transporter and subsequent serotonin release with a possible participation of other neuroendocrine regulatory systems.

Putting clinical pharmacology in context: the use of popular movies.

The usefulness of movies to illustrate the psychological and sociological conflicts of medical practice is widely recognized. However, the use of popular movies to teach less oriented medical sciences, such as pharmacology is not so common. In the present review, we report the use of three films (Awakenings, Lorenzo's Oil, and Miss Evers' Boys) as a teaching tool to allow students to better understand some conflicts which appear in the domain of clinical pharmacology. These movies may help to introduce some relevant topics such as the difficulties of planning and performing clinical research with new drugs, the need of considering bioethical principles when doing research with human beings, and the social and psychological aspects of drug therapy. The films may increase the motivation of students to understand clinical pharmacology principles and may become a driving force for an increased desire to learn.

Determination of MDMA and its metabolites in blood and urine by gas chromatography-mass spectrometry and analysis of enantiomers by capillary electrophoresis.

A gas chromatography-mass spectrometry (GC-MS) method was used for the simultaneous quantitation of 3,4-methylenedioxymethamphetamine (MDMA) and the 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxymethamphetamine (HMMA), and 4-hydroxy-3-methoxyamphetamine (HMA) metabolites in plasma and urine samples after the administration of 100 mg MDMA to healthy volunteers. Samples were hydrolyzed prior to a solid-phase extraction with Bond Elut Certify columns. Analytes were eluted with ethyl acetate (2% ammonium hydroxide) and analyzed as their trifluoroacyl derivatives. Linear calibration curves were obtained at plasma and urine concentration ranges of 25-400 ng/mL and 250-2000 ng/mL for MDMA and HMMA, and of 2.5-40 ng/mL and 100-1000 ng/mL for MDA and HMA. Following the same urine preparation procedure but without the derivatization step, a capillary electrophoresis (CE) method for enantiomerical resolution of compounds was developed using (2-hydroxy)propyl-beta-cyclodextrin at two different concentrations (10 and 50mM in 50mM H3PO4, pH 2.5) as chiral selector. Calibration curves for the CE method were prepared with the corresponding racemic mixture and were linear between 125 and 2000 ng/mL, 50 and 1000 ng/mL, and 125 and 1500 ng/mL for each enantiomer of MDMA, MDA, and HMMA, respectively. Stereoselective disposition of MDMA and MDA was confirmed. HMMA disposition seems to be in apparent contradiction with MDMA findings as the enantiomer ratio is close to 1 and constant over the time.

3,4-Methylenedioxymethamphetamine (ecstasy) and alcohol interactions in humans: psychomotor performance, subjective effects, and pharmacokinetics.

3,4-Methylenedioxymethamphetamine (MDMA) is frequently consumed in association with alcohol. The effect of this combination in humans has not been previously investigated. Nine male healthy volunteers received single oral doses of 100 mg of MDMA plus 0.8 g/kg ethanol, 100 mg of MDMA, 0.8 g/kg of ethanol, and placebo in a double blind, double dummy, randomized crossover trial. Measurements included psychomotor performance, subjective effects, and pharmacokinetics. Plasma concentrations of MDMA showed a 13% increase after the use of alcohol, whereas plasma concentrations of alcohol showed a 9 to 15% decrease after MDMA administration. The MDMA-alcohol combination induced longer lasting euphoria and well being than MDMA or alcohol alone. MDMA reversed the subjective sedation induced by alcohol but did not reduce drunkenness feelings. MDMA did not reverse the actions of alcohol on psychomotor abilities. Combined use of MDMA and alcohol causes dissociation between subjective and objective sedation. Subjects may feel euphoric and less sedated and might have the feeling of doing better, but actual performance ability continues to be impaired by the effect of alcohol. Confirmation of these findings in further studies will be highly relevant in terms of road safety.