MDMA Halflife
In the last few years there has been some good research done on the pharmacokinetics of MDMA by Mendelson and colleagues at UCSF (unpublished) and by de la Torre and colleagues, published in the Annals of the New York Academy of Science (2000). One major piece of pharmacology which most users don't know and isn't intuitively obvious is that MDMA's elimination half-life in humans is quite long, around 9 hours. This means that 9 hours after you swallow a single dose of ecstasy, concentrations in the blood have only dropped to half of their peak levels. MDMA levels are still at 1/4 their peak 18 hours after ingestion and 1/8 of their peak levels at 27 hours. It isn't until more than a day and a half after taking MDMA that the body is no longer experiencing direct pharmacological effects of the chemical.