Cycles of amphetamine and cocaine abuse have occurred throughout the world for more than a century. In the United States, use of methamphetamine, which is the primary type of amphetamine abused, has dramatically increased. The number of admissions for methamphetamine treatment increased nearly fourfold from 1994 to 2004. In many areas of the country, the number of patients enrolled for methamphetamine treatment surpasses the number of patients in treatment for cocaine and heroin. Cocaine also remains a major public health issue, based on arrest statistics and drug treatment records. In fact, emergency room visits related to cocaine use increased by more than 22% between 1994 and 2001 (Office of National Drug Control Policy 2001; Substance Abuse and Mental Health Services Administration 2006a, 2006b).