Methylenedioxyphenethylamines

3,4-methylenedioxy-substituted phenethylamines and amphetamines: MDMA, MDA, MDEA, MBDB, MDOH, MMDA and BDB. The methylenedioxy bridge is what shifts a stimulant scaffold towards serotonin release, and it is why these are filed under Entactogens rather than Stimulants or Psychedelics. Members differ more than the shared ring suggests — MDA is longer and carries genuine psychedelic character, and the N-alkyl homologues are duller and shorter-lived.

MDMA is metabolised in part to MDA, and it inhibits the enzyme doing that metabolising, so exposure climbs faster than dose does: a second dose in a night is not equivalent to the first. The class-level harms are hyperthermia, hyponatraemia, serotonin syndrome with MAOIs and SSRIs, and cardiac strain. Tablets sold as MDMA are also where PMA and PMMA, filed under Psychedelic Phenethylamines, turn up.