New designer drug p-methoxymethamphetamine: studies on its metabolism and toxicological detection in urine using gas chromatography–mass spectrometry

https://doi.org/10.1016/S1570-0232(02)01018-8Get rights and content

Abstract

Studies are described on the metabolism and the toxicological analysis of the new designer drug rac-p-methoxymethamphetamine (PMMA) in rat urine using gas chromatography–mass spectrometry (GC–MS). The identified metabolites indicated that PMMA was extensively metabolized mainly by O-demethylation to pholedrine and to a minor extent to p-methoxyamphetamine (PMA), 1-hydroxypholedrine diastereomers (one being oxilofrine), 4′-hydroxy-3′-methoxymethamphetamine and 4′-hydroxy-3′-methoxyamphetamine. The authors’ systematic toxicological analysis (STA) procedure using full-scan GC–MS after acid hydrolysis, liquid–liquid extraction and microwave-assisted acetylation allowed the detection of the main metabolites of PMMA in rat urine after a dose corresponding to that of drug users. Therefore, this procedure should be suitable for detection of PMMA intake in human urine via its metabolites. However, it must be considered that pholedrine and oxilofrine are also in therapeutic use. Differentiation of PMMA, PMA and/or pholedrine intake is discussed.

Introduction

A wide variety of phenylisopropylamine derivatives are offered and consumed as drugs of abuse. One of these derivatives, p-methoxymethamphetamine [PMMA, R,S-N-methyl-1-(4-methoxyphenyl)-2-aminopropane], has surfaced on the illicit drug market in form of tablets containing PMMA only as well as mixtures with other designer drugs [1], [2], [3], [4], [5]. It is already scheduled in the German Act of Controlled substances and, according to a decision of the council of the EU, will be placed under control measures and criminal penalties in all EU member states [6]. PMMA is the N-methyl analogue of the common designer drug p-methoxyamphetamine [PMA, R,S-1-(4-methoxyphenyl)-2-aminopropane] which has been responsible for a number of fatalities in Europe, Australia and the USA [7], [8], [9], [10], [11], [12], [13], [14]. Mixtures of both compounds have also been seized and fatalities after intake of these mixtures have been reported [2], [3]. The PMMA isomer methoxyphenamine [R,S-N-methyl-1-(2-methoxyphenyl)-2-aminopropane, Orthoxine®] was in use as a bronchodilator [15]. Analytical differentiation of the two isomers was described by Dal Cason [4].

Pharmacological discrimination studies using rats showed that PMMA lacks amphetamine-like effects in contrast to PMA. It was shown to share considerable similarities with MDMA [R,S-N-methyl-1-(3,4-methylenedioxyphenyl)-2-aminopropane], but without the amphetaminergic stimulant component of MDMA. It produced stimulant effects similar to MBDB [R,S-N-methyl-1-(3,4-methylenedioxyphenyl)-2-aminobutane] and DMA [1-(3,4-dimethoxyphenyl)-2-aminopropane] [16], [17], [18], [19], [20]. The only data available on the effects in humans has been published by Shulgin, who described its effects as somewhat different from those of MDMA [21]. Structurally related compounds which are widely abused have been shown to possess serotonergic neurotoxic potential. Likewise, Steel et al. showed long-term (possibly neurotoxic) effects on brain serotonin neurons for PMMA, however, being less potent compared to neurotoxic effects of MDMA [5]. Furthermore, they uttered concerns about the possibility of a narrow margin between the behaviorally active and lethal doses of PMMA as described for PMA. This was due to their observation of 43% lethality in male Spague–Dawley rats after the administration of 80 mg/kg body mass.

The metabolism of PMMA has not been studied yet. However, the knowledge about metabolic steps is a prerequisite for developing toxicological screening procedures and for toxicological risk assessment, as in both cases the metabolites may play a major role. So far, only few analytical data on PMMA itself have been published [4]. Screening procedures for detection of PMMA and its metabolites have not been published yet.

Therefore, the aim of the presented study was to identify the PMMA metabolites in rat urine using GC–MS in the electron impact (EI) and positive-ion chemical ionization (PICI) mode and to study the detectability of PMMA within the authors’ systematic toxicological analysis (STA) procedure in urine by GC–MS in the EI mode [22], [23].

Section snippets

Chemicals and reagents

All chemicals and biochemicals used were obtained from Merck (Darmstadt, Germany) and were of analytical grade. rac-PMMA–HCl and rac-PMA–HCl as reference metabolites were provided by Bayerisches Landeskriminalamt (Munich, Germany) for research purposes before the drug had been scheduled in the German Controlled Substances Act. Pholedrine was obtained from Sigma (Taufkirchen, Germany) and oxilofrine from Aventis Pharma (Bad Soden, Germany).

Urine samples

The investigations were performed using urine of male

Sample preparation

Cleavage of conjugates was necessary before extraction and GC–MS analysis of the suspected metabolites in order not to overlook conjugated metabolites. For studies on the metabolism, gentle enzymatic hydrolysis was preferred, whereas for studies on the toxicological detection, rapid acid hydrolysis was performed. Acid hydrolysis has proved to be very efficient and fast for cleavage of conjugates [22], [26], [30], [31], [32], [33]. However, some compounds covered by this STA are altered or

Conclusions

The presented studies showed that PMMA is extensively metabolized. Urine screening must be focused on the main metabolite pholedrine. For differentiation of an illegal intake of PMMA from a legal intake of pholedrine, it should be screened for the parent compound and the minor but more unique metabolites PMA and 4-HO-AM. The authors’ STA procedure allowed the detection of an intake of a dose of PMMA, that corresponds to a common drug users’ dose in rat urine via its metabolites. Therefore, it

Acknowledgements

The authors thank Wolfgang Roemhild, Magdeburg, Thomas Kraemer, Frank T. Peters, Dietmar Springer, Gabriele Ulrich and Armin A. Weber, Homburg, for their support.

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