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Denis S Theobald

Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, University of Saarland, D-66421 Homburg (Saar), Germany.

5 papers in the library · 250 citations · publishing 2005-2007

Papers

Screening for and validated quantification of phenethylamine-type designer drugs and mescaline in human blood plasma by gas chromatography/mass spectrometry.

Journal of mass spectrometry : JMS June 1, 2005 Vilma Habrdova, Frank T Peters, Denis S Theobald et al. 61 citations

A new method using gas chromatography/mass spectrometry was developed to screen and quantify seven 2C-series designer drugs (2C-D, 2C-E, 2C-P, 2C-B, 2C-I, 2C-T-2, 2C-T-7) and mescaline in human blood plasma. The method involves solid-phase extraction and derivatization, and was validated per international guidelines. Validation for 2C-T-2 and 2C-T-7 was unacceptable; for the other analytes, the method was linear from 5 to 500 microg/L with accuracy and precision within acceptable limits. This addresses the scarcity of data on analyzing these substances in blood or plasma.

DOI: 10.1002/jms.853 Full text Mescaline Drug detection Substance identification Drug screening +24

Identification of monoamine oxidase and cytochrome P450 isoenzymes involved in the deamination of phenethylamine-derived designer drugs (2C-series).

Biochemical pharmacology January 15, 2007 Denis S Theobald, Hans H Maurer 59 citations

For several phenethylamine-type designer drugs (2C-series), the main metabolic step is deamination to an aldehyde. Using human enzymes expressed in cell culture, monoamine oxidase A and B (MAO-A and MAO-B) were the primary catalysts of this reaction for all compounds tested. For four of the six drugs (2C-D, 2C-E, 2C-T-2, and 2C-T-7), the cytochrome P450 enzyme CYP2D6 contributed to a very small extent. Because MAO enzymes are the major route of metabolism, these designer drugs are likely to be susceptible to drug-drug interactions with MAO inhibitors.

DOI: 10.1016/j.bcp.2006.09.022 Full text Drug metabolism Designer drugs Mao enzymes Drug interactions

New designer drug 4-iodo-2,5-dimethoxy-beta-phenethylamine (2C-I): studies on its metabolism and toxicological detection in rat urine using gas chromatographic/mass spectrometric and capillary electrophoretic/mass spectrometric techniques.

Journal of mass spectrometry : JMS July 1, 2006 Denis S Theobald, Michael Pütz, Erhard Schneider et al. 51 citations

The designer drug 2C-I is metabolized in rats through O-demethylation, deamination, oxidation, and reduction pathways, producing multiple metabolites that are partly excreted in conjugated form. A systematic toxicological analysis using gas chromatography/mass spectrometry after acid hydrolysis, liquid-liquid extraction, and microwave-assisted acetylation reliably detected a dose of 2C-I in rat urine equivalent to a common human drug user's dose. Assuming similar metabolism in humans, this detection method should be suitable for proving 2C-I intake in human urine.

DOI: 10.1002/jms.1045 Full text Toxicology: human toxicology Drug detection Detecting Reliably detected +11

Studies on the metabolism and toxicological detection of the designer drug 4-ethyl-2,5-dimethoxy-beta-phenethylamine (2C-E) in rat urine using gas chromatographic-mass spectrometric techniques.

Journal of chromatography. B, Analytical technologies in the biomedical and life sciences October 2, 2006 Denis S Theobald, Hans H Maurer 42 citations

The designer drug 2C-E is metabolized in rats through several pathways: O-demethylation, N-acetylation, hydroxylation of the ethyl side chain, oxidation to ketones or acids, and deamination followed by reduction to alcohols. Most metabolites are excreted in conjugated form. A systematic toxicological analysis using full-scan GC-MS detected intake of a dose corresponding to a common drug users' dose in rat urine. Assuming similar metabolism in humans, the procedure should be suitable for proving 2C-E intake in human urine.

DOI: 10.1016/j.jchromb.2006.03.001 Full text Drug metabolism Biotransformation Drug processing Metabolic changes +18

Studies on the toxicological detection of the designer drug 4-bromo-2,5-dimethoxy-beta-phenethylamine (2C-B) in rat urine using gas chromatography-mass spectrometry.

Journal of chromatography. B, Analytical technologies in the biomedical and life sciences February 1, 2007 Denis S Theobald, Giselher Fritschi, Hans H Maurer 37 citations

The designer drug 2C-B is extensively metabolized and excreted mainly as metabolites in urine. In rats, a systematic toxicological analysis using full-scan GC-MS detected the O-demethyl deaminohydroxy metabolite and two isomers of the O-demethyl metabolite after a common drug abuser's dose. The authors suggest that, assuming similar metabolism in humans, this procedure should be suitable for proving 2C-B intake in human urine.

DOI: 10.1016/j.jchromb.2006.08.049 Full text Drug detection Drug testing Drug screening Substance detection +20