Pharmacological Interaction Between Clonidine and Methylenedioxymethamphetamine (MDMA)

3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") is widely used by young people for its euphoric effects. MDMA releases serotonin (5-HT), norepinephrine (NE), and dopamine. It is unknown which of these monoamines mainly contributes to the subjective and physiological effects of MDMA in humans. Clonidine is a centrally acting alpha2-receptor agonist and sympatholytic which attenuates the release of NE from presynaptic nerve terminals and also lowers NE plasma concentration. To determine the role of NE in the response to MDMA in humans we test the effects of a clonidine pretreatment on the pharmacodynamics and pharmacokinetics of MDMA. We use a randomized double-blind placebo-controlled cross-over design with four experimental sessions. Clonidine (150 μg) or placebo will be administered 1 h before the administration of MDMA (125 mg) or placebo to 16 healthy volunteers. Subjective and cardiovascular responses will be repeatedly assessed throughout the experiments and plasma samples are collected for pharmacokinetics. We hypothesize that clonidine will significantly attenuate predominantly the cardiovascular response to MDMA.