Dextroamphetamine Sulfate

dextroamphetamine sulfate (dex troe am fet' a meen) Dexedrine, Dexedrine Spansule, DextroStat Pregnancy Category C Controlled Substance C-II Drug classes

Amphetamine CNS stimulant Therapeutic actions

Acts in the CNS to release norepinephrine from nerve terminals; in higher doses also releases dopamine; suppresses appetite; increases alertness, elevates mood; often improves physical performance, especially when fatigue and sleep-deprivation have caused impairment; efficacy in hyperkinetic syndrome, attention-deficit disorders in children appears paradoxical and is not understood. Indications

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Narcolepsy Adjunct therapy for abnormal behavioral syndrome in children (attention-deficit disorder, hyperkinetic syndrome) that includes psychological, social, educational measures

Contraindications and cautions

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Hypersensitivity to sympathomimetic amines, tartrazine (Dexedrine); advanced arteriosclerosis, symptomatic CV disease, moderate to severe hypertension, hyperthyroidism, glaucoma, agitated states, history of drug abuse; pregnancy; lactation.

Available forms

Tablets—5, 10, 15 mg; SR capsules—5, 10, 15 mg; CR capsules—10, 15 mg Dosages ADULTS

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Narcolepsy: Start with 10 mg/day PO in divided doses; increase in increments of 10 mg/day at weekly intervals. If insomnia, anorexia occur, reduce dose. Usual dosage is 5–60 mg/day PO in divided doses. Give first dose on awakening, additional doses (one or two) q 4–6 hr; long-acting forms can be given once a day.

PEDIATRIC PATIENTS

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Narcolepsy: 6–12 yr: Condition is rare in children < 12 yr; when it does occur, initial dose is 5 mg/day PO. Increase in increments of 5 mg at weekly intervals until optimal response is obtained. >12 yr: Use adult dosage.

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Attention-deficit disorder: < 3 yr: Not recommended. 3–5 yr: 2.5 mg/day PO. Increase in increments of 2.5 mg/day at weekly intervals until optimal response is obtained. > 6 yr: 5 mg PO daily–bid. Increase in increments of 5 mg/day at weekly intervals until optimal response is obtained. Dosage will rarely exceed 40 mg/day. Give first dose on awakening, additional doses (one or two) q 4–6 hr. Long-acting forms may be used once a day.

Pharmacokinetics Route Oral

Onset Rapid

Peak 1–5 hr

Duration 8–10 hr

Metabolism: Hepatic; T1/2: 10–30 hr Distribution: Crosses placenta; enters breast milk Excretion: Urine Adverse effects

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CNS: Overstimulation, restlessness, dizziness, insomnia, dyskinesia, euphoria, dysphoria, tremor, headache, psychotic episodes CV: Palpitations, tachycardia, hypertension Dermatologic: Urticaria Endocrine: Reversible elevations in serum thyroxine with heavy use GI: Dry mouth, unpleasant taste, diarrhea, constipation, anorexia and weight loss GU: Impotence, changes in libido Other: Tolerance, psychological dependence, social disability with abuse

Interactions

Drug-drug • Hypertensive crisis and increased CNS effects if given within 14 days of MAOIs; do not give dextroamphetamine to patients who are taking or who have recently taken MAOIs • Increased duration of effects if taken with urinary alkalinizers (acetazolamide, sodium bicarbonate), furazolidone • Decreased effects if taken with urinary acidifiers • Decreased efficacy of antihypertensive drugs (guanethidine) given with amphetamines Nursing considerations Assessment

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History: Hypersensitivity to sympathomimetic amines, tartrazine; advanced arteriosclerosis, symptomatic CV disease, moderate to severe hypertension, hyperthyroidism, glaucoma, agitated states, history of drug abuse; lactation, pregnancy

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Physical: Weight; T; skin color, lesions; orientation, affect, ophthalmic exam (tonometry); P, BP, auscultation; R, adventitious sounds; bowel sounds, normal output; thyroid function tests, blood and urine glucose, baseline ECG

Interventions

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Ensure proper diagnosis before administering to children for behavioral syndromes. Drug should not be used until other causes (learning disability, EEG abnormalities, neurologic deficits) are ruled out. Interrupt drug dosage periodically in children being treated for behavioral disorders to determine if symptomatic response still validates drug therapy. Monitor growth of children on long-term amphetamine therapy. Dispense the lowest feasible dose to minimize risk of overdosage; should be in a light-resistant container. Ensure that patient swallows SR tablets whole; do not cut, crush, or chew. Give drug early in the day to prevent insomnia. Monitor BP frequently early in therapy.

Teaching points

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Take this drug exactly as prescribed. Do not increase the dosage without consulting your physician. If the drug appears ineffective, consult your health care provider. Do not crush or chew sustained-release or long-acting tablets. Take drug early in the day (especially sustained-release preparations) to avoid insomnia. Avoid pregnancy while taking this drug. This drug can cause harm to the fetus. These side effects may occur: Nervousness, restlessness, dizziness, insomnia, impaired thinking (may diminish in a few days; avoid driving or engaging in activities that require alertness); headache, loss of appetite, dry mouth. Report nervousness, insomnia, dizziness, palpitations, anorexia, GI disturbances.

Adverse effects in Italic are most common; those in Bold are life-threatening.