“Club drugs” have become alarmingly popular. The use of 3,4‐methylenedioxymethamphetamine (MDMA, Ecstasy) and γ‐hydroxybutyrate (GHB), in particular, has increased dramatically from 1997–1999. The pharmacokinetics of MDMA and GHB appear to be nonlinear, making it difficult to estimate a dose‐response relationship. The drug MDMA is an amphetamine analog with sympathomimetic properties, whereas...