Objectives: Remarkable interindividual differences in 3,4-methylenedioxymethamphetamine ('Ecstasy')-mediated toxicity have been reported in humans. Therefore, we tested whether CYP2D6 or its variant alleles as well as CYP3A4 influence the susceptibility to 3,4-methylenedioxymethamphetamine.
Methods: 3,4-Methylenedioxymethamphetamine cytotoxicity was determined in V79 cells expressing human wild-type CYP2D6 (CYP2D6*1), the low-activity alleles CYP2D6*2, *9, *10, and *17, as well as human CYP3A4. Metabolites of 3,4-methylenedioxymethamphetamine formed by the different cell lines were quantified by high-performance liquid chromatography/electrochemical detector.
Results: Toxicity of 3,4-methylenedioxymethamphetamine was clearly increased in cells expressing CYP2D6*1 compared with the parental cells devoid of CYP-dependent enzymatic activity. Toxicity in V79 CYP2D6*1 cells was also higher than in V79 cell lines expressing the low-activity alleles CYP2D6*2, *9, *10, or *17. In contrast to CYP2D6, the CYP3A4 isoenzyme did not enhance 3,4-methylenedioxymethamphetamine toxicity. Formation of the oxidative 3,4-methylenedioxymethamphetamine metabolite N-methyl-alpha-methyldopamine was greatly enhanced in V79 cell line transfected with CYP2D6*1 compared to all other cell lines. The increase in the cytotoxic effects of 3,4-methylenedioxymethamphetamine observed in this cell line was therefore suspected to be a consequence of the production of this metabolite. This was further investigated by testing the cytotoxicity of N-methyl-alpha-methyldopamine to the control cell line. The results confirmed our hypothesis as the metabolite proved to be more than 100-fold more toxic than the parent compound 3,4-methylenedioxymethamphetamine.
Conclusions: CYP2D6*1 mediates 3,4-methylenedioxymethamphetamine toxicity via formation of N-methyl-alpha-methyldopamine. Therefore, it will be important to investigate whether CYP2D6 ultrarapid metabolizers are overrepresented in the cases of 3,4-methylenedioxymethamphetamine intoxications.