"Some amphetamines, including dextroamphetamine, methamphetamine, and the related methylphenidate, are widely used medically to treat attention-deficit hyperactivity disorder, obesity, and narcolepsy, thus creating a supply subject to diversion for illicit use. Methamphetamine is easily manufactured illicitly."
Source
"Amphetamines," The Merck Manual for Health Care Professionals, Special Subjects: Drug Use and Dependence: Amphetamines, Merck & Co. Inc. (July 2008).
http://www.merckmanuals.com/p…
