DEXTROAMPHETAMINE SULFATE

DEXTROAMPHETAMINE SULFATE
(dex-troe-am-fet'a-meen)
Dexampex, Dexedrine, Oxydess II , Spancap No. 1
Classifications: respiratory and cerebral stimulant; amphetamine; anorexiant;
Therapeutic:amphetamine; anorexiant

Prototype: Amphetamine
Pregnancy Category: C
Controlled Substance: Schedule II

Availability

5 mg, 10 mg tablets; 5 mg, 10 mg, 15 mg sustained release capsules

Action

An isomer of amphetamine, it has anorexigenic action; this is thought to result from CNS stimulation and possibly from loss of acuity of smell and taste.

Therapeutic Effect

Is a more potent appetite suppressant than amphetamine. CNS stimulating effect approximately twice that of racemic amphetamine. In hyperkinetic children, amphetamines reduce motor restlessness by an unknown mechanism.

Uses

Adjunct in short-term treatment of exogenous obesity, narcolepsy, and attention deficit disorder with hyperactivity in children (also called minimal brain dysfunction or hyperkinetic syndrome).

Unlabeled Uses

Adjunct in epilepsy to control ataxia and drowsiness induced by barbiturates; to combat sedative effects of trimethadione in absence seizures.

Contraindications

Hypersensitivity to sympathomimetic amines, closed-angle glaucoma, agitated states, psychoses (especially in children), structural cardiac abnormalities, valvular heart disease; congenital heart disease, coronary heart disease, advanced arteriosclerosis, symptomatic heart disease, moderate to severe hypertension, hyperthyroidism, history of drug abuse, during or within 14 d of MAO INHIBITOR therapy, as anorexiant in children <12 y, for attention deficit disorder in children <3 y, pregnancy (category C); lactation.

Cautious Use

Bipolar disease; salicylate hypersensitivity; seizure disorders; suicidal ideation, depression; salicylate hypersensitivity. Safety and efficacy in children <3 y have not been established.

Route & Dosage

Narcolepsy
Adult: PO 5–20 mg 1–3 times/d at 4–6 h intervals
Child: PO 6–12 y, 5 mg/d, may increase by 5 mg at weekly intervals; >12 y, 10 mg/d, may increase by 10 mg at weekly intervals

Attention Deficit Disorder
Child: PO 3–5 y, 2.5 mg 1–2 times/d, may increase by 2.5 mg at weekly intervals; ≥6 y, 5 mg 1–2 times/d, may increase by 5 mg at weekly intervals (max: 40 mg/d)

Obesity
Adult: PO 5–10 mg 1–3 times/d or 10–15 mg of sustained release once/d 30–60 min a.c.

Administration

Oral
  • Ensure that sustained release capsule is not chewed or crushed. It MUST be swallowed whole.
  • Give 30–60 min before meals for treatment of obesity. Give long-acting form in the morning.
  • Give last dose no later than 6 h before patient retires (10–14 h before bedtime for sustained release form) to avoid insomnia.
  • Store in tightly closed containers at 15°–30° C (59°–86° F) unless otherwise directed.

Adverse Effects (≥1%)

CNS: Nervousness, restlessness, hyperactivity, insomnia, euphoria, dizziness, headache; with prolonged use: severe depression, psychotic reactions. CV: Palpitations, tachycardia, elevated BP. GI: Dry mouth, unpleasant taste, anorexia, weight loss, diarrhea, constipation, abdominal pain. Other: Impotence, changes in libido, unusual fatigue, increased intraocular pressure, marked dystonia of head, neck, and extremities; sweating.

Diagnostic Test Interference

Dextroamphetamine may cause significant elevations in plasma corticosteroids (evening levels are highest) and increases in urinary epinephrine excretion (during first 3 h after drug administration).

Interactions

Drug: Acetazolamide, sodium bicarbonate decrease dextroamphetamine elimination; ammonium chloride, ascorbic acid increase dextroamphetamine elimination; effects of both barbiturates and dextroamphetamine may be antagonized; furazolidone may increase BP effects of amphetamines—interaction may persist for several weeks after discontinuing furazolidone; antagonizes antihypertensive effects of guanethidine; mao inhibitors, selegiline can cause—hypertensive crisis (fatalities reported)—do not administer amphetamines during or within 14 d of these drugs; phenothiazines may inhibit mood elevating effects of amphetamines; tricyclic antidepressants enhance dextroamphetamine effects because of increased norepinephrine release; beta-adrenergic agonists increase cardiovascular adverse effects.

Pharmacokinetics

Absorption: Rapid. Peak: 1–5 h. Duration: Up to 10 h. Distribution: All tissues especially the CNS. Metabolism: In liver. Elimination: Renal elimination; excreted in breast milk. Half-Life: 10–30 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor children, adolescents, and adults for signs and symptoms of adverse cardiac reactions (e.g., arrhythmias).
  • Monitor growth rate closely in children.
  • Interrupt therapy or reduce dosage periodically to assess effectiveness in behavior disorders.
  • Monitor children and adolescents for development of aggressive or abnormal behaviors.
  • Note: Tolerance to anorexiant effects may develop after a few weeks; however, tolerance does not appear to develop when dextroamphetamine is used to treat narcolepsy.

Patient & Family Education

  • Swallow sustained release capsule whole with a liquid; do not chew or crush.
  • Do not drive or engage in other potentially hazardous activities until response to drug is known.
  • Taper drug gradually following long-term use to avoid extreme fatigue, mental depression, and prolonged sleep pattern.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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