HEALTH-SYSTEM EDITION

P&T PORTFOLIO

Generic name

Dextroamphetamine

Proprietary name/manufacturer

Dexedrine/GlaxoSmithKline

FDA-approved indications

Treatment of attention deficit hyperactivity disorder (ADHD); treatment of narcolepsy

Pharmacology

Dextroamphetamine is a noncatechol sympathetic amine with CNS stimulant activity. The drug is thought to have a direct effect on both alpha- and beta-receptor sites in the peripheral system and to release norepinephrine in adrenergic nerve terminals. The CNS action is thought to occur in the cerebral cortex and reticular activating system. Its mechanism of action for the treatment of ADHD has not been clearly elucidated. Dextroamphetamine sustained-release capsules (Spansules) are formulated to release the active drug in a more gradual fashion than the standard formulation.

Efficacy

Several controlled clinical trials have shown the effectiveness of dextroamphetamine as an integral part of a total treatment program for some adults and children with ADHD. In these studies, dextroamphetamine has been shown to improve symptoms of hyperkinesis, hyperactivity, and minimal brain dysfunction as measured by an increase in attention span and reduction of purposeless activity. Both dextroamphetamine and methylphenidate appear similar in effectiveness and well tolerated when used to treat ADHD. In addition, dextroamphetamine (immediate- and extended-release) appears similar in efficacy to amphetamine mixture (immediate-release) for the treatment of children with ADHD. However, clinical comparisons between dextroamphetamine and other agents used to treat ADHD are lacking.

In a once-daily dose study, dextroamphetamine (immediate- and extended-release) demonstrated similar efficacy to amphetamine mixture (immediate-release Adderall) for the treatment of children with ADHD. Both immediate-release agents demonstrated earlier onset of activity, but dextroamphetamine extended-release capsules showed more sustained effects.

Contraindications

• Advanced arteriosclerosis

• Symptomatic cardiovascular disease

• Moderate to severe hypertension

• Hyperthyroidism

• Hypersensitivity or idiosyncrasy to the sympathomimetic amines

• Glaucoma

• Agitated states

• History of drug abuse

• During or within 14 days following the administration of MAO inhibitors

Adverse effects

• Cardiovascular (palpitations, tachycardia, elevated blood pressure)

• CNS (overstimulation, restlessness, dizziness, insomnia, euphoria, dyskinesia, dysphoria, tremor, headache, exacerbation of motor and phonic tics, and Tourette's syndrome)

• GI (dry mouth, unpleasant taste, diarrhea, constipation, anorexia and weight loss)

• Allergic (urticaria)

• Endocrine (impotence, changes in libido)

Pharmacokinetics

Dose for ADHD

• Pediatric patients ages three to five: 2.5 mg daily (daily dose may be increased by 2.5 mg/week until optimal response)

• Pediatric patients six years and older: 5 mg once or twice daily (may increase daily dose by 5 mg/week until optimal response)

Note: Spansule capsules may be used for once-a-day dosage whenever appropriate.

Conclusion/comments

Dextroamphetamine, the d-isomer of amphetamine, is a CNS stimulant that has demonstrated efficacy in the treatment of ADHD, a neurobehavioral disorder that affects an estimated 4% to 12% of school-age children, especially boys. Symptoms generally include a short attention span and behavioral problems. The American Academy of Pediatrics supports the use of CNS stimulants in most children six to 12 years of age who have been diagnosed with ADHD, as long as there are clear treatment goals and the children are carefully monitored.

Published March 2002. Content based on medical literature and product information available at that time.

 

P&T Portfolio: Dexedrine. Drug Topics 2002;8:HSE22.