R/S concentration ratios for MDMA, MDA, DHMA 3-sulfate, DHMA 4-sulfate, HMMA sulfate, and HMMA glucuronide over time. Black circles and solid lines represent 13 CYP2D6 extensive metabolizers (EM). Triangles and dotted lines represent three CYP2D6 intermediate metabolizers (IM). Open circles and solid lines represent 13 CYP2D6 EMs after pretreatment with bupropion. The data are expressed as mean and SEM. *p < 0.05, **p < 0.01, ***p < 0.001, significant within-subject difference between placebo+MDMA and bupropion+MDMA in CYP2D6 EM subjects (Wilcoxon matched-pairs test); +p < 0.05, ++p < 0.01, significant differences between placebo+MDMA-treated CYP2D6 IMs and bupropion+MDMA-treated CYP2D6 EMs (Mann-Whitney test).