Abstract
para-Methyl-4-methylaminorex (4,4′-DMAR) is a phenethylamine derivative with psychostimulant activity whose abuse has been associated with several deaths and a wide range of adverse effects. We recently validated a high-performance liquid chromatography—tandem mass spectrometry method to measure the compound’s concentrations in plasma, and we applied it to describe the pharmacokinetic properties of 4,4′-DMAR after a single dose in rats. In this study, we investigated the brain disposition and metabolism of cis-4,4′-DMAR after intraperitoneal injection as well as its central behavioral effects. Locomotor activity increased after a single injection of 10 mg/kg, peaking at 2 hours and disappearing at 5 hours; in these conditions, brain absorption was very rapid, (tmax = 30–60 minutes) and large (brain-to-plasma ratio = 24); the half-life was approximately 50 minutes. After 14 daily doses, the compound’s effect on locomotor activity was greater (approximately 20% compared with the effect after the first dose), but not for pharmacokinetic reasons. Using high-resolution mass spectrometry, we also identified four metabolites of cis-4,4′-DMAR in the plasma and brain of treated rats. Semiquantitative analysis indicated low brain permeability and very low brain concentrations, suggesting that these metabolites do not contribute to central behavioral effects; however, the metabolite originating from oxidation of the para-methyl group (M2) persisted in the plasma longer and at higher concentrations than the parent molecule and could be used to evaluate drug intake in human consumers. Finally, we describe the rewarding effect of cis-4,4′-DMAR in the conditioning place preference test, suggesting a high risk of addiction in humans.
Footnotes
- Received February 16, 2017.
- Accepted April 3, 2017.
↵1 Current affiliation: Department of Diagnostics and Public Health, Verona University, Verona, Italy.
This research was supported by the Drug Policies Department of the Presidency of the Council of Ministers of Italy [Project NPS-Risk Assessment].
↵This article has supplemental material available at jpet.aspetjournals.org.
- Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics
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