Ask Dr. Shulgin Online ARCHIVE: August 27, 2001 MDMA Isomers Dear Dr. Shulgin: What are the differences between the physical and mental effects of the different isomers of MDMA? I have heard that the "R" isomer is more prone to produce the empathy feeling. --B-Zen

Dear B-Zen: Early in my studies of MDMA, I wanted to determine what the effects were for each of the two optical isomers of the compound. This question was of particular interest to me becuase MDMA was, in a structural sense, a hybrid of two classes of compounds. It had an amphetamine skeleton, as do amphetamine and methamphetamine. With both of these two stimulants, it is the dextro-isomer (the + isomer, the "S" isomer) that is the more potent compound. However, in a series of early studies with the psychedelic amphetamine compounds, those with 3,4- disubstitution such as MDA and TMA-2, the increased potency always leaned towards the - isomers, those with the "R" configuration. I felt that to assay the "S" and "R" isomers of MDMA might help me towards answering a question: Was this compound basically a stimulant drug with some minor leanings towards a psychedelic (the "S" isomer is the more effective one) or is it a psychedelic drug with minor leanings towards a stimulant (the "R" isomer would be the more effective one). I received research samples of each of the two isomers from my NIMH contacts, and set up a pretty much blind study. One of the results was clear and not unexpected. The "S" isomer was clearly the more potent one -- the effective dose was between 60 and 120 milligrams, whereas the "R" isomer was barely threshold at 160 milligrams. This was about a 2:1 weight ratio favoring the "S" or "stimulant" isomer as defining the action. What was unexpected was that neither isomer gave the magic of the racemic MDMA. It was almost as if both the separate pharmacological components needed to be present to experience the unusual properties of this drug. Someday in the distant future, when research can be easily conducted on compounds such as this one, I hope this study will be repeated. If this proves to be correct, I am sure that there is much to be learned from subtle combinations of drugs with opposite effects. But with the present "War on Drugs" crusade against any and all inquiry into the action of psychedelic drugs, this probably will not occur within my lifetime. -- Dr. Shulgin Terms of Use