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A Sweet Spot for MDMA doses? An interesting new paper by Tibor M. Brunt, Maarten W. Koeter, Raymond J. M. Niesink and Wim van den Brink analyzed ecstasy pills and effects descriptions of 5,786 anonymous drug users who handed in their tablets for chemical analysis at the Drug Information and Monitoring System in the Netherlands. MDMA alone was in almost 70% of tablets. Average MDMA dose was 82.5 mg (SD: 35.2, range: 2.0–218.0). Since people submitting the tablets briefly described the effects, the authors were able to make the attached analysis of how MDMA dose influences probability of positive (solid line) and adverse (dotted line) effects. Positive effects peak around 81-100 mg, while adverse effects become increasingly likely at doses over 121 mg. Comparing drugs, they find evidence that mephedrone and p-fluoroamphetamine may have MDMA-like social/entactogenic effects. Most (97.4%) of the adverse subjective effects reported were associated with: mCPP; MDMA; MDMA+mCPP; MDA; MDMA+p-methoxymethamphetamine (PMMA); amphetamine; benzylpiperazine (BZP); mCPP+metoclopramide; and 2 CB. Overall, MDMA had the highest probability of a desirable effect and a low probability of adverse effect (although sample sizes were small for some drugs like mephedrone).
Paper is (sadly) behind a paywall:

Tibor M. Brunt, Maarten W. Koeter, Raymond J. M. Niesink and Wim van den Brink
Linking the pharmacological content of ecstasy tablets to the subjective experiences of drug usersPsychopharmacology DOI: 10.1007/s00213-011-2529-4
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