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Markus R. Meyer

Saarland University

8 papers in the library · 281 citations · publishing 2009-2025

Papers

Absorption, Distribution, Metabolism and Excretion Pharmacogenomics of Drugs of Abuse

Pharmacogenomics February 1, 2011 Markus R. Meyer, Hans H. Maurer 107 citations

The effects of drugs of abuse and other foreign substances depend on an individual's genetic makeup and the specific enzymes that break down those substances. This article summarizes current knowledge about the enzymes—such as cytochrome P450, glucuronyltransferases, esterases, and reductases—involved in metabolizing frequently abused opioids (oxycodone, hydrocodone, methadone, fentanyl, buprenorphine, tramadol, heroin, morphine, codeine), anesthetics (GHB, propofol, ketamine, phencyclidine), cognitive enhancers (methylphenidate, modafinil), plant-derived hallucinogens (LSD, salvinorin A, psilocybin, psilocin), and nicotine. Understanding these metabolic pathways helps predict drug interactions, explain individual differences in drug response, assess toxicity, and improve drug testing interpretation.

Enantioselectivity in the Methylation of the Catecholic Phase I Metabolites of Methylenedioxy Designer Drugs and Their Capability To Inhibit Catechol-O-methyltransferase-Catalyzed Dopamine 3-Methylation

Chemical Research in Toxicology May 22, 2009 Markus R. Meyer, Hans H. Maurer 39 citations

The designer drugs MDMA, MDEA, and MBDB are chiral compounds whose metabolism is enantioselective, favoring the S-enantiomer. This study investigated whether the elimination of their catecholamine metabolites via O-methylation by catechol-O-methyltransferase (COMT) is also enantioselective. Using human liver cytosol and microsomes, the S-enantiomers of all three catecholamines were preferentially O-methylated by both soluble and membrane-bound COMT. The membrane-bound COMT had 10-fold higher affinity for substrates, while the soluble form had 10-fold higher turnover rate. All tested catechols uncompetitively inhibited dopamine methylation. Enantioselective elimination may contribute to different pharmacokinetic properties of the enantiomers.

Pharmacological and biotransformation studies of 1-acyl-substituted derivatives of -lysergic acid diethylamide (LSD)

Neuropharmacology November 19, 2019 Adam L. Halberstadt, Muhammad Chatha, Adam K. Klein et al. 37 citations

The ergoline d-lysergic acid diethylamide (LSD) is one of the most potent psychedelic drugs. 1-Acetyl-LSD (ALD-52) and other 1-acyl-substituted LSD derivatives, including 1-propanoyl-LSD (1P-LSD) and 1-butanoyl-LSD (1B-LSD), have appeared as designer drugs assumed to act as prodrugs for LSD. Competitive binding studies and calcium mobilization assays showed 1-acyl-substitution reduced affinity for most monoamine receptors, including 5-HT2A sites, by one to two orders of magnitude, and these derivatives had weak efficacy or acted as antagonists in Ca2+-mobilization assays. Despite this, they induced head twitches in mice with relatively high potency. High levels of LSD were detected in rat plasma after subcutaneous administration of ALD-52 and 1P-LSD, demonstrating rapid and efficient deacylation in vivo, consistent with the prediction that these compounds serve as prodrugs for LSD.

Urinary Excretion Kinetics of 3,4-Methylenedioxymethamphetamine (MDMA, Ecstasy) and Its Phase I and Phase II Metabolites in Humans following Controlled MDMA Administration

Clinical Chemistry October 7, 2011 Andrea E. Schwaninger, Markus R. Meyer, Allan J. Barnes et al. 33 citations

After oral MDMA (ecstasy) intake, human urine contains mostly sulfate and glucuronide conjugates of MDMA metabolites, with sulfates present at higher concentrations than glucuronides. More than 90% of the metabolites DHMA and HMMA were excreted as conjugates. HMMA sulfate had the longest detection window in urine. The ratio of HMMA sulfate to glucuronide was 2.0, and the ratio of DHMA 3-sulfate to 4-sulfate was 5.3 during the first 24 hours, matching predictions from earlier lab experiments. These findings can improve direct urine analysis for MDMA and its metabolites in clinical and forensic toxicology.

Screening for illicit drugs in pooled human urine and urinated soil samples and studies on the stability of urinary excretion products of cocaine, MDMA, and MDEA in wastewater by hyphenated mass spectrometry techniques

Drug Testing and Analysis February 17, 2016 Marie Mardal, Juliet Kinyua, Pedram Ramin et al. 31 citations

Wastewater-based epidemiology can track community drug use, but biomarkers are often diluted. Pooled urine and urinated soil from festivals were screened for illicit drug excretion products. Cocaine and ecstasy-like compounds were most frequent. A method was developed to quantify their excretion products. Hydroxymethoxymethamphetamine (HMMA), MDMA, MDA, HMMA sulfate, benzoylecgonine, and cocaethylene retained 85–102% of initial concentration after 8 hours, while cocaine and ecgonine methyl ester dropped to 74% and 67%, respectively. HMMA increased over 24 hours, likely from conjugate cleavage and MDMA biotransformation. HMMA is suggested as a stable analytical target for MDMA consumption in wastewater.

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

Biochemical Pharmacology September 29, 2011 Andrea E. Schwaninger, Markus R. Meyer, Allan J. Barnes et al. 23 citations

The R- and S-enantiomers of MDMA are eliminated differently in human urine. After controlled oral doses of 1.0 and 1.6 mg/kg, urine from ten participants was analyzed. Over five days, a median of 21% of the measured compounds were excreted as R-stereoisomers and 17% as S-stereoisomers. Significantly more R-enantiomers of MDMA, DHMA, and HMMA sulfate were excreted, while more S-stereoisomers of HMMA and HMMA glucuronide were excreted. No significant differences appeared for MDA and DHMA sulfate. The ratio of R- to S-stereoisomers changed steadily over the first 48 hours, suggesting it could help estimate time of MDMA ingestion in clinical and forensic toxicology.

Can the Intake of a Synthetic Tryptamine be Detected Only by Blood Plasma Analysis? A Clinical Toxicology Case Involving 4-HO-MET

Journal of Analytical Toxicology June 3, 2021 Lea Wagmann, Sascha K. Manier, Markus R. Meyer 11 citations

A non-fatal clinical case involving the synthetic tryptamine 4-HO-MET (metocin or methylcybin) was analyzed using blood plasma. Liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-HRMS-MS) detected the parent compound and four metabolites—N-demethyl-, oxo-, hydroxy-4-HO-MET, and the N-oxide—while gas chromatography-mass spectrometry did not detect it. The plasma concentration of 4-HO-MET was 193 ng/mL. These findings provide data for clinical and forensic toxicologists interpreting future cases involving synthetic tryptamines, particularly when only blood samples are available.

Next-Generation MDMA Analogue SDMA: Pharmacological and Metabolic Insights

ACS Chemical Neuroscience December 2, 2025 Nina Kastner, Núria Nadal‐gratacós, Selina Hemmer et al.

Replacing the 1,3-benzodioxole group in MDMA (ecstasy) with a 1,3-benzoxathiole yields two analogues, SDA and SDMA, that interact with monoamine transporters similarly to MDMA but with key differences. SDA and SDMA inhibit dopamine and norepinephrine transporters more potently than MDMA and act as partial releasers at serotonin and dopamine transporters. Metabolism studies show SDA and SDMA are cleared faster, while MDMA and MDA degrade only weakly. In mice, SDMA does not produce rewarding effects, unlike MDMA, and SDA only shows a preference for the drug-paired compartment at the lowest dose. SDMA shares similar locomotor and hyperthermic profiles with MDMA, whereas SDA induces increased hyperlocomotion and more sustained hyperthermia. SDMA may be a safer candidate for further study.