Adult: Initially, 100 mg daily, increased to 100 mg bid after a wk or more. Max dose: 400 mg daily. Elderly: >65 yr Lowest effective dose.
Oral Prophylaxis of influenza A
Adult: 100 mg daily for up to 6 wk; when used w/ influenza vaccination: only up to 3 wk after vaccination. Elderly: >65 yr <100 mg daily or 100 mg given at intervals >1 day. Child: 10-15 yr 100 mg daily.
Oral Influenza A
Adult: 100 mg daily for 5 days. Elderly: >65 yr <100 mg daily or 100 mg given at intervals >1 day. Child: 10-15 yr 100 mg daily.
Oral Herpes zoster (shingles)
Adult: 100 mg bid for 14 days, may continue for another 14 days if pain persists.
Oral Drug-induced extrapyramidal symptoms
Adult: 200 mg daily in 2 divided doses, increased up to 300 mg daily if needed.
Renal Impairment
CrCl (mL/min)
Dosage
<15
Not recommended.
15-35
100 mg every 2-3 days.
>35
100 mg daily.
Administration
Should be taken with food.
Contraindications
Hypersensitivity to amantadine. History of epilepsy or other seizure disorders, history of gastric ulceration. Severe renal impairment (CrCl <15 mL/min). Lactation.
Special Precautions
Patient w/ or history of CV disease, recurrent eczema, psychiatric disorders, untreated angle-closure glaucoma. Avoid abrupt withdrawal. Hepatic and mild to moderate renal impairment. Childn, elderly. Pregnancy.
This drug may cause dizziness, blurred vision or impair alertness, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor renal function, BP, Parkinson’s or influenza symptoms, mental status.
Overdosage
Symptoms: Acute psychosis, hyperreflexia, motor restlessness, convulsions, extrapyramidal signs, torsion spasms, dystonic posturing, dilated pupils, dysphagia, confusion, disorientation, delirium, visual hallucinations, myoclonus; hyperventilation, pulmonary oedema, resp distress; cardiac arrest and sudden cardiac death, sinus tachycardia, arrhythmia, HTN; nausea, vomiting, dry mouth; urine retention, renal dysfunction, including increased BUN and decreased CrCl. Management: Induce vomiting and/or gastric aspiration (and lavage if patient is conscious); activated charcoal or saline cathartic may be used. Maintain renal function and employ copious diuresis (forced diuresis if necessary) for effective removal from the blood stream. Acidification increases rate of excretion. Administer anticonvulsants (e.g. diazepam IV, paraldehyde IM or per rectum, phenobarbital IM) to treat convulsions and excessive motor restlessness. Acute psychotic symptoms, delirium, dystonic posturing, myoclonic manifestations may be treated w/ physostigmine.
Drug Interactions
Increased risk of confusion, hallucinations, nightmares, GI disturbances or other atropine-like side effects w/ anticholinergic agents or levodopa. Psychotic symptoms may worsen w/ concomitant neuroleptic medication. Additive CNS toxicity w/ drugs acting on CNS. Reduced renal clearance w/ quinine or quinidine.
Food Interaction
Increased CNS effects w/ alcohol.
Lab Interference
May cause false-positive result w/ urine detection of amphetamines/methamphetamines.
Action
Description: Mechanism of Action: Amantadine is a weak dopamine agonist possessing antimuscarinic properties. It alters dopamine release and re-uptake. It also noncompetitively antagonises N-methyl-D-aspartate. As an antiviral drug, it inhibits replication of influenza type A virus. Onset: Antidyskinetic: W/in 48 hr. Pharmacokinetics: Absorption: Well absorbed from the GI tract. Time to peak concentration: W/in approx 4 hrs. Distribution: Crosses the placenta and the blood-brain barrier; enters breast milk. Volume of distribution: 3-8 L/kg. Plasma protein binding: Approx 67%; w/ substantial amount bound to erythrocytes (approx 2.7 times higher than in plasma). Metabolism: Metabolised to a minor extent, mainly by N-acetylation. Excretion: Via urine (80-90% as unchanged drug and small amounts of an acetylated metabolite). Plasma elimination half-life: Approx 15 hr.
Chemical Structure
Amantadine Source: National Center for Biotechnology Information. PubChem Database. Amantadine, CID=2130, https://pubchem.ncbi.nlm.nih.gov/compound/Amantadine (accessed on Jan. 20, 2020)
N04BB01 - amantadine ; Belongs to the class of adamantane derivative dopaminergic agents. Used in the management of Parkinson's disease.
References
Amantadine HCl Capsule, Liquid filled (Banner Life Sciences LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 10/02/2016 .Anon. Amantadine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 10/02/2016 .Buckingham R (ed). Amantadine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 10/02/2016 .McEvoy GK, Snow EK, Miller J et al (eds). Amantadine Hydrochloride (Antiparkinson). AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 10/02/2016 .McEvoy GK, Snow EK, Miller J et al (eds). Amantadine Hydrochloride (Antiviral). AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 10/02/2016 .
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