Adult: Initially, 5-10 mg daily in divided doses, increased by 5-10 mg every wk. Maintenance to be given in 2-4 divided doses. Max: 60 mg daily. Elderly: Initially, 5 mg daily in divided doses, increased by 5 mg every wk. Maintenance to be given in 2-4 divided doses. Max: 60 mg daily. Child: 6-12 yr Initially, 5 mg daily in divided doses, increased by 5 mg every wk. Maintenance to be given in 2-4 divided doses. Max: 60 mg daily.
Oral Attention deficit hyperactivity disorder
Child: 3-5 yr As immediate-release tab or soln: Initially, 2.5 mg daily, raised in increments of 2.5 mg at wkly intervals; ≥6 yr Initially, 5 mg once or twice daily, increased if necessary by 5 mg at wkly intervals. Max: 20 mg daily; older childn may require up to 40 mg or more daily.
Administration
May be taken with or without food.
Contraindications
Patient w/ CV disease including moderate to severe HTN, structural cardiac abnormalities, cardiomyopathy, advanced arteriosclerosis; hyperthyroidism, glaucoma, hyperexcitability or agitated states, phaeochromocytoma, porphyria, Tourette's syndrome or similar dystonias; history of drug or alcohol abuse. Concomitant use w/ MAOIs or w/in 14 days of MAOI treatment.
Special Precautions
Patient w/ mild HTN, bipolar disorder, unstable personality, epilepsy; predisposition to tics or Tourette's syndrome. Renal or hepatic impairment. Pregnancy and lactation.
Adverse Reactions
Insomnia, night terrors, nervousness, restlessness, irritability, euphoria, fatigue, depression; dryness of the mouth, anorexia, abdominal cramps and other GI disturbances; headache, dizziness, tremor, sweating; tachycardia, palpitations, MI, increased or decreased BP, altered libido, impotence; hallucinations, delusional thinking, mania, seizures, stroke; muscle damage w/ associated rhabdomyolysis and renal complications. Rarely, cardiomyopathy.
Monitor height and wt in childn as growth retardation may occur. During initial treatment, observe for aggressive behaviour or hostility. Record pulse, BP, psychiatric symptoms and appetite at initiation, following each dose adjustment, and at least 6 mthly thereafter therapy.
Overdosage
Symptoms: Restlessness, tremor, hyperreflexia, rhabdomyolysis, rapid respiration, hyperpyrexia, confusion, assaultiveness, hallucinations, panic states; arrhythmias, HTN or hypotension, circulatory collapse; nausea, vomiting, diarrhoea, abdominal cramps; convulsions, coma. Management: Symptomatic treatment. Gastric lavage, admin of activated charcoal, admin of a cathartic and sedation. If acute, severe HTN complicates overdosage, may administer IV phentolamine. May use chlorpromazine to treat intoxication since it antagonises the central stimulant effects of amfetamines.
Drug Interactions
Severe HTN w/ β-blockers. May diminish effects of other antihypertensives (e.g. guanethidine) and similar drugs. Increased risk of CV effects (e.g. arrhythmias) w/ TCAs or volatile liq anaesth (e.g. halothane). Urinary excretion is reduced by urinary alkalinisers and increased by acidifiers. May delay absorption of ethosuximide, phenobarbital and phenytoin. Stimulant effects are inhibited by chlorpromazine, haloperidol and lithium. Inhibition of metabolism and excretion w/ disulfiram. Potentially Fatal: Increased risk of hypertensive crisis w/ patients being treated w/ MAOIs or w/in 14 days of stopping MAOI treatment.
Food Interaction
Reduced serum levels if taken w/ acidic food, juices.
Lab Interference
May interfere w/ urinary steroid determinations.
Action
Description: Mechanism of Action: Dexamfetamine is the dextrorotatory isomer of amfetamine. Amfetamines are noncatecholamine, sympathomimetic amines that promote release of catecholamines (mainly dopamine and norepinephrine) from their storage sites in the presynaptic nerve terminals. Duration: Immediate release: 4-6 hr; extended-release: 8 hr. Pharmacokinetics: Absorption: Readily absorbed from the GI tract. Time to peak plasma concentration: Approx 3 hr (immediate release); approx 8 hr (extended-release). Distribution: Distributed into most body tissues w/ high concentrations in the brain and CSF. Crosses the blood-brain barrier and enters breast milk. Plasma protein binding: 15-34%. Metabolism: Undergoes partial hepatic metabolism by CYP monooxygenase and via glucuronidation. Excretion: Via urine as unchanged drug. Elimination half-life: 10-12 hr.
Chemical Structure
Source: National Center for Biotechnology Information. PubChem Database. Dextroamphetamine, CID=5826, https://pubchem.ncbi.nlm.nih.gov/compound/Dextroamphetamine (accessed on Jan. 20, 2020)
N06BA02 - dexamfetamine ; Belongs to the class of centrally-acting sympathomimetics. Used as CNS stimulant.
References
Anon. Dextroamphetamine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 10/03/2016.Buckingham R (ed). Dexamfetamine Sulfate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com . Accessed 10/03/2016.Dextroamphetamine Sulfate Capsule, Extended Release (Actavis Pharma, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 10/03/2014.Dextroamphetamine Sulfate Tablet (Ethex Corporation). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 10/03/2016.Joint Formulary Committee. Dexamfetamine Sulfate. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 10/03/2016.McEvoy GK, Snow EK, Miller J et al (eds). Dextroamphetamine Saccharate, Dextroamphetamine Sulfate. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 10/03/2016.
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