Psychopharmacology
June 30, 2011
M. Kirkpatrick, Erik W. Gunderson, Audrey Y. Perez et al.
119 citations
Methamphetamine and MDMA, despite chemical similarities, produce both overlapping and distinct effects in the same individuals. In a residential study with 11 adult volunteers, both drugs acutely increased cardiovascular measures and positive subjective effects while decreasing food intake. Participants had difficulty distinguishing between the drugs. Methamphetamine improved cognitive performance and disrupted sleep, whereas MDMA increased negative subjective-effect ratings. Few residual effects were noted for either drug. These differences may help explain the drugs' differing public perception and abuse potential, though recreational route of administration could also account for many attributed effects.
Psychoneuroendocrinology
April 19, 2014
M. Kirkpatrick, Sunday M. Francis, Royce J. Lee et al.
106 citations
MDMA (ecstasy) increases feelings of sociability and closeness. This study tested whether those effects come from a rise in the hormone oxytocin. In 14 healthy MDMA users given MDMA, oxytocin nasal spray, or placebo, only the higher MDMA dose (1.5 mg/kg) raised blood oxytocin levels to a peak of 83.7 pg/ml around 90–120 minutes, versus 18.6 pg/ml after placebo. The higher oxytocin spray (40 IU) raised levels to 48.0 pg/ml. MDMA increased heart rate, blood pressure, and feelings of euphoria and sociability, but oxytocin spray did not. The subjective effects of MDMA were not linked to oxytocin levels, suggesting oxytocin may not be the main cause of MDMA's prosocial effects.
Psychopharmacology
March 15, 2014
M. Kirkpatrick, M. Baggott, J. Mendelson et al.
78 citations
Across three independent laboratories in Basel, San Francisco, and Chicago, 220 healthy volunteers received either placebo or MDMA (1.5 mg/kg or a 125-mg fixed dose) under double-blind conditions. Despite differences in study methods and participants' prior drug use, MDMA produced very similar cardiovascular and subjective effects at all sites. Prior MDMA use was inversely related to feeling "Any Drug Effect" only at sites testing more experienced users. The pharmacological effects of MDMA are robust and highly reproducible across settings, with modest evidence for tolerance in regular users.