The science of stimulant abuse.

Stimulant medications, although classified by the US Drug Enforcement Agency as controlled with a Schedule IIa rating, are ubiquitous in our society because of their popularity as an effective treatment for childhood ADHD. The number of stimulant products available for practitioners has tripled in the last decade. Although stimulants' action on central dopamine systems can be reinforcing, especially when delivered via intraperitoneal or intravenous routes in laboratory animals, they are far less addicting when taken orally by children in the context of a medical treatment. Fortunately, the therapeutic stimulants, available orally, have different pharmacodynamic and pharmacokinetic properties than the illicit stimulants, methamphetamine and cocaine. The lack of intravenous forms of the therapeutic stimulants acts as a natural barrier and tends to prevent addiction. Furthermore, MPH produces dysphoria in school age children, further limiting its reinforcing properties. These pharmacokinetics and pharmacodynamics of methylphenidate and amphetamine treatments for ADHD thus are less addicting because of their delivery systems. Future products, employing novel methods that only allow the drug molecule to be available if ingested, should further increase the safety of these important therapeutic agents.