dextroamphetamine

dextroamphetamine, chemical compound known for its stimulatory effects on the central nervous system (CNS). Dextroamphetamine is commonly used to treat narcolepsy and to control symptoms of attention-deficit/hyperactivity disorder (ADHD). It is marketed under the brand names Dexedrine Spansule, ProCentra, and Zenzedi and often is combined with amphetamine in a formulation marketed as Adderall.

History

The first amphetamine compound was synthesized by Romanian chemist Lazar Edeleanu in 1887. The effects of the drug, however, were not well understood. In the late 1920s amphetamine was synthesized again, by American chemist Gordon Alles, in the form of amphetamine sulfate. Its stimulant effects were recognized soon after, with the dextro enantiomer—dextroamphetamine—found to be the more potent of the molecule’s two isomers. In 1937 the pharmaceutical company Smith, Kline, and French began to synthesize and market dextroamphetamine under the name Dexedrine. As more-stringent drug regulations were implemented in the following decades, Dexedrine was formally approved by the U.S. Food and Drug Administration (FDA) in 1976 to treat ADHD and narcolepsy. In 1996 Adderall entered the market and quickly supplanted Dexedrine as the drug of choice for ADHD.

Use and mechanisms

Dextroamphetamine controls symptoms of ADHD and narcolepsy by increasing attention and wakefulness and decreasing restlessness. It stimulates the CNS via its sympathomimetic actions, which mimic natural mechanisms of sympathetic nervous system stimulation. Other effects associated with dextroamphetamine include increased blood pressure and respiratory stimulation. Medications that include dextroamphetamine can take the form of liquid, tablet, or extended-release capsule.

The exact mechanisms by which dextroamphetamine produces its effects remain unclear. The drug induces chemical changes within the brain by inhibiting the reuptake into neurons of monoamine neurotransmitters, such as dopamine, norepinephrine, and serotonin, that are released into the synaptic cleft (the space between the ends of neurons). In addition, dextroamphetamine directly stimulates the release of dopamine and norepinephrine from neurons. The physiological significance of these actions is unknown.

Side effects and potential for misuse

Dextroamphetamine can cause a variety of side effects, the most common of which include headache, insomnia, weight loss, dry mouth, and changes in libido. More significant side effects can include seizures, mood or behavioral changes, and changes in cardiovascular function. Dextroamphetamine-based medications also may interact with other prescription and non-prescription medications, as well as with vitamin and herbal supplements. The drug also can adversely affect patients with other medical conditions, particularly glaucoma, hyperthyroidism, heart conditions, or mood disorders. Dextroamphetamine poses additional risks in young patients, in whom it can potentially affect growth and induce severe cardiovascular anomalies that culminate in sudden death.

Dextroamphetamine can become addictive when taken improperly, especially when taken in unusually large doses, at increased frequency, or for long periods of time. Excessive misuse of dextroamphetamine may lead to overdose, which is associated with a variety of symptoms, ranging from restlessness and dizziness to seizures, loss of consciousness, and death. In the United States both dextroamphetamine sulfate and dextroamphetamine-amphetamine are classified by the FDA and the Drug Enforcement Administration as Schedule II controlled substances, a classification indicating high risk for abuse.