Pharmacological and toxicological effects of beta-3,4-methylenedioxyamphetamine isomers

Enantioselective degradation of amphetamine-like environmental micropollutants (amphetamine, methamphetamine, MDMA and MDA) in urban water

This paper aims to understand enantioselective transformation of amphetamine, methamphetamine, MDMA (3,4-methylenedioxy-methamphetamine) and MDA (3,4-methylenedioxyamphetamine) during wastewater treatment and in receiving waters. In order to undertake a comprehensive evaluation of the processes occurring, stereoselective transformation of amphetamine-like compounds was studied, for the first time, in controlled laboratory experiments: receiving water and activated sludge simulating microcosm systems. The results demonstrated that stereoselective degradation, via microbial metabolic processes favouring S-(+)-enantiomer, occurred in all studied amphetamine-based compounds in activated sludge simulating microcosms. R-(-)-enantiomers were not degraded (or their degradation was limited) which proves their more recalcitrant nature. Out of all four amphetamine-like compounds studied, amphetamine was the most susceptible to biodegradation. It was followed by MDMA and methamphetamine. Photochemical processes facilitated degradation of MDMA and methamphetamine but they were not, as expected, stereoselective. Preferential biodegradation of S-(+)-methamphetamine led to the formation of S-(+)-amphetamine. Racemic MDMA was stereoselectively biodegraded by activated sludge which led to its enrichment with R-(-)-enantiomer and formation of S-(+)-MDA. Interestingly, there was only mild stereoselectivity observed during MDMA degradation in rivers. This might be due to different microbial communities utilised during activated sludge treatment and those present in the environment. Kinetic studies confirmed the recalcitrant nature of MDMA.

Prostaglandin H synthase-catalyzed bioactivation of amphetamines to free radical intermediates that cause CNS regional DNA oxidation and nerve terminal degeneration

Reactive oxygen species (ROS) are implicated in amphetamine-initiated neurodegeneration, but the mechanism is unclear. Here, we show that amphetamines are bioactivated by CNS prostaglandin H synthase (PHS) to free radical intermediates that cause ROS formation and neurodegenerative oxidative DNA damage. In vitro incubations of purified PHS-1 with 3,4-methylenedioxyamphetamine (MDA) and methamphetamine (METH) demonstrated PHS-catalyzed time- and concentration-dependent formation of an amphetamine carbon- and/or nitrogen-centered free radical intermediate, and stereoselective oxidative DNA damage, evidenced by 8-oxo-2'-deoxyguanosine (8-oxo-dG) formation. Similarly in vivo, MDA and METH caused dose- and time-dependent DNA oxidation in multiple brain regions, remarkably dependent on the regional PHS levels, including the striatum and substantia nigra, wherein neurodegeneration of dopaminergic nerve terminals was evidenced by decreased immunohistochemical staining of tyrosine hydroxylase. Motor impairment using the rotarod test was evident within 3 wk after the last drug dose, and persisted for at least 6 months. Pretreatment with the PHS inhibitor acetylsalicylic acid blocked MDA-initiated DNA oxidation and protected against functional motor impairment for at least 1.5 months after drug treatment. This is the first direct evidence for PHS-catalyzed bioactivation of amphetamines causing temporal and regional differences in CNS oxidative DNA damage directly related to structural and functional neurodegenerative consequences.

Stereochemical effects of 3,4-methylenedioxymethamphetamine (MDMA) and related amphetamine derivatives on inhibition of uptake of [3H]monoamines into synaptosomes from different regions of rat brain

3,4-Methylenedioxymethamphetamine (MDMA) is a recently popularized recreational drug, although some have advocated its psychotherapeutic potential. Since the pharmacology of MDMA is largely uncharacterized, the stereochemical profiles of MDMA and some of its homologs were derived on inhibition of synaptosomal uptake of [3H]monoamines and compared to those of amphetamine and the hallucinogenic phenylisopropylamine 2,5-dimethoxy-4-methylamphetamine (DOM). In contrast to the 5-fold stereoselectivity observed with amphetamine, only the S-(+) enantiomer of MDMA and 3,4-methylenedioxyamphetamine (MDA) inhibited [3H]dopamine uptake into striatal synaptosomes. Neither stereoisomer of the alpha-ethyl homolog of MDMA, N-methyl-1-(1,3-benzodioxol-5-yl)-2-butanamine (MBDB), inhibited [3H]dopamine uptake. The two stereoisomers of amphetamine and the MDMA-related compounds were equipotent in inhibiting [3H]norepinephrine uptake into hypothalamic synaptosomes. Both stereoisomers of MDMA, MDA and MBDB were potent inhibitors of [3H]serotonin uptake into hippocampal synaptosomes, but only S-(+)-amphetamine produced an appreciable inhibition of [3H]serotonin uptake. Neither stereoisomer of DOM inhibited synaptosomal uptake of any [3H]monoamine. These results suggest that MDMA and its homologs may be more closely related to amphetamine rather than to DOM in their biochemical mode of action. The pronounced effects of the methylenedioxy-substituted compounds on [3H]serotonin and [3H]norepinephrine uptake implicate these neurotransmitters in the pharmacological effects of these drugs.

Pharmacodynamic modeling of the EEG effects of ketamine and its enantiomers in man

The pharmacodynamics of a racemic mixture of ketamine R,S(+/-)-ketamine and of each enantiomer, S(+)-ketamine and R(-)-ketamine, were studied in five volunteers. The median frequency of the electroencephalogram (EEG) power spectrum, a continuous noninvasive measure of the degree of central nervous system (CNS) depression (pharmacodynamics), was related to measured serum concentrations of drug (pharmacokinetics). The concentration-effect relationship was described by an inhibitory sigmoid Emax pharmacodynamic model, yielding estimates of both maximal effect (Emax) and sensitivity (IC50) to the racemic and enantiomeric forms of ketamine. R(-)-ketamine was not as effective as R,S(+/-)-ketamine or S(+)-ketamine in causing EEG slowing. The maximal decrease (mean +/- SD) of the median frequency (Emax) for R(-)-ketamine was 4.4 +/- 0.5 Hz and was significantly different from R,S(+/-)-ketamine (7.6 +/- 1.7 Hz) and S(+)-ketamine (8.3 +/- 1.9 Hz). The ketamine serum concentration that caused one-half of the maximal median frequency decrease (IC50) was 1.8 +/- 0.5 micrograms/mL for R(-)-ketamine; 2.0 +/- 0.5 micrograms/mL for R,S(+/-)-ketamine; and 0.8 +/- 0.4 microgram/mL for S(+)-ketamine. Because the maximal effect (Emax) of the R(-)-ketamine was different from that of S(+)-ketamine and R,S(+/-)-ketamine, it was not possible to directly compare the potency (i.e., IC50) of these compounds. Accordingly, a classical agonist/partial-agonist interaction model was examined, using the separate enantiomer results to predict racemate results. Although the model did not predict racemate results well, its failure was not so great as to provide clear evidence of synergism (or excess antagonism) of the enantiomers.

Ecstacy: a review of MDMA and MDA

The Drug Enforcement Administration classified the drug methylenedioxymethamphetamine, MDMA, also known as Ecstacy, as a Schedule I controlled substance on July 1, 1985. The controversy surrounding the classification of MDMA is related to the question of its efficacy as an adjunct to psychotherapy and the larger issue of how to regulate the production and use of designer drugs. The authors review the literature on MDMA and its predecessor, MDA, a substance that differs from MDMA by one methyl group.

Effects of an i.v. lethal dose of 3,4-methylenedioxyamphetamine (MDA) in the dog and antagonism by chlorpromazine

A high intravenous (i.v.) dose of MDA (20 mg/kg) to mongrel dogs elevated body temperature, heart rate, mean arterial pressure and other cardiovascular parameters initially, but only the 1st two remained high. Other functions soon became quite depressed, and death shortly ensued. Arterial pO2 decreased, but pH and pCO2 showed a biphasic response after an initial decrease, Dogs that received chlorpromazine (10 mg/kg, i.v.) after MDA showed stabilization of physiological parameters, and survival through 48 hr.

Hallucinogenic amphetamine selectively destroys brain serotonin nerve terminals

(+/-)-3,4-Methylenedioxyamphetamine (MDA), an amphetamine analog with hallucinogenic activity, produced selective long-lasting reductions in the level of serotonin, the number of serotonin uptake sites, and the concentration of 5-hydroxyindoleacetic acid in rat brain. Morphological studies suggested that these neurochemical deficits were due to serotonin nerve terminal degeneration. These results show that MDA has toxic activity for serotonin neurons in rats and raise the question of whether exposure to MDA and related hallucinogenic amphetamines can produce serotonin neurotoxicity in the human brain.

3,4-methylenedioxyamphetamine overdose

MDA was indicated in the death of a 35-year-old male. Blood, tissue, and urine concentrations of MDA were measured by ultraviolet spectrophotometry after identification by gas chromatography/mass spectrometry. The concentrations found were within the range of previously reported fatal MDA levels.