The subjective effects of MDMA and mCPP in moderate MDMA users.

The present study is part of a research program designed to better understand the neurochemical mechanisms underlying the abuse liability of 3,4-methylenedioxymethamphetamine (MDMA) in humans. In these studies, MDMA will be compared to prototypical dopamine (D-amphetamine) and serotonin (meta-chlorophenylpiperazine, mCPP) releasing agents on a variety of measures related to dependence. In order to determine an acceptable dose range (safe but active) of MDMA and mCPP for these studies, moderate MDMA users were administered escalating doses of MDMA (75, 110 and 145 mg/70 kg) and mCPP (17.5, 35 and 52.5 mg/70 kg). Each participant received a single dose under controlled laboratory conditions, i.e. this was a six-group design with a separate group for each dose. There were five participants tested in each group. MDMA increased blood pressure and heart rate whereas mCPP had no effect on these physiological measures. MDMA produced increases in subjective effects indicative of both stimulant (increases in POMS Elation, ARCI Amphetamine, VAS High and Stimulated scale scores) and hallucinogenic effects (increases on five of the six scales of the Hallucinogenic Rating Scale). mCPP produced similar stimulant effects (e.g. increases on POMS Elation, VAS High and Stimulated), as well as hallucinogenic effects (four of the six scales of the Hallucinogenic Rating Scale), which has not been observed in previous studies.