Aims: Not every tablet sold as "ecstasy" contains MDMA (3,4-methylenedioxymethamphetamine). The historical origins and evolution of this mismatch will be reviewed, in order to estimate the proportions of ecstasy tablets containing MDMA at different periods over the past 30 years.
Methods: Surveys into the pharmacological constituents of ecstasy tablets, dosage levels, and empirical reports of their perceived purity, provide the main data for this review.
Results: During the 1980s and early 1990s there were few problems with the purity of ecstasy tablets, and the biochemical evidence shows that they nearly always contained MDMA. During the mid-1990s, the majority of ecstasy tablets continued to contain MDMA, while many others comprised MDA (3,4-methylenedioxyamphetamine), MDEA (3,4-methylenedioxyethylamphetamine), or amphetamine drug mixtures. However, a small proportion (4-20% according to survey, time and place), comprised non-amphetamine drugs such as caffeine, ephedrine, ketamine, paracetamol, or placebo. During the late 1990s, the proportion of ecstasy tablets containing MDMA increased to around 80-90%. The latest reports suggest that non-MDMA tablets are now very infrequent, with purity levels between 90% and 100%. Dosage levels of tablets are also highly variable, with low dose tablet often encountered during the mid-1990s, and high dose tablets now seen more frequently. The theoretical and practical implications of these findings will be debated.
Conclusions: The ecstasy purity problem was predominantly a phenomenon of the mid to late 1990s, when many tablets contained substances other than MDMA. Before and since then, the proportion of ecstasy tablets containing MDMA has been very high.