Trade Names:Symmetrel- Tablets 100 mg- Syrup 50 mg/5 mL
Trade Names:Amantadine Hydrochloride- Capsules 100 mgEndantadine (Canada)Gen-Amantadine (Antiparkinsonian) (Canada)Gen-Amantadine (Antiviral) (Canada)
Exact mechanism is unknown; thought to facilitate dopamine release from intact dopaminergic terminals, increasing dopamine concentration at dopaminergic terminals. Exhibits antiviral activity against influenza A virus by inhibiting entry of virus into host cell.
Well absorbed. C max is about 0.22 mcg/mL and T max is about 3.3 h.
Vd is 3 to 8 L/kg and about 67% protein bound.
8 metabolites were identified.
Primarily excreted unchanged in the urine. Cl is about 0.28 L/h/kg. The t ½ is about 17 h. Excretion increases when urine is acidic.
Elimination t ½ increased 2- to 3-fold or greater when Ccr is less than 40 mL/min/1.73 m 2 .Elderly
Cl reduced and plasma t ½ and concentrations are increased.
Symptomatic treatment of several forms of Parkinson disease or syndrome and drug-induced extrapyramidal reactions; prevention and treatment of influenza A viral respiratory illness, especially in high-risk patients.H1Na Influenza A (Swine Flu)
Per the CDC recommendations for treatment and chemoprophylaxis of H1N1 influenza A (swine flu) virus infection, refer to the oseltamivir and zanamivir A to Z monographs. The H1N1 virus is resistant to the antiviral medication amantadine. For more information, refer to the CDC guidelines at http://www.cdc.gov/h1n1flu/recommendations.htm .
PO 100 mg twice daily when used as single agent.Initial dose
PO 100 mg/day if patient is debilitated or receiving high doses of other antiparkinson drugs. If necessary, dose may be titrated to max of 400 mg/day.Drug-Induced Extrapyramidal ReactionsAdults
PO 100 mg twice daily; up to 300 mg/day may be given in divided doses.Influenza A Viral Infection (Symptomatic Treatment)Adults
PO 200 mg/day as single dose or 100 mg twice daily. If CNS effects develop on a once-daily dosage, split dosage schedule may reduce complaints.Elderly over 65 yr of age
PO 100 mg every day.Children 9 to 12 yr of age
PO 100 mg twice daily.Children 1 to 9 yr of age
PO 4.4 to 8.8 mg/kg/day; not to exceed 150 mg/day.Renal ImpairmentAdults
PO Ccr 30 to 50 mL/min: Administer 200 mg first day followed by 100 mg/day thereafter; Ccr 15 to 29 mL/min: Administer 200 mg first day followed by 100 mg on alternate days; Ccr less than 15 mL/min and hemodialysis patients: Administer 200 mg every 7 days.Influenza A Viral Infection (Prophylaxis)
Same dosages as for symptomatic treatment. However, start in anticipation of contact or as soon as possible after exposure. Continue drug administration for at least 10 days after known exposure. When influenza A virus vaccine is unavailable or contraindicated, administer amantadine for up to 90 days. In conjunction with the vaccine, administer amantadine for 2 to 3 wk after vaccination.
Store tablets, capsules, and syrup at controlled room temperature (59° to 86°F).
May increase the effects of amantadine.CNS stimulants
The effects of the CNS stimulant may be increased by amantadine.
None well documented.
Orthostatic hypotension (1% to 5%); cardiac arrest, arrhythmias (including malignant arrhythmias), hypotension, tachycardia (postmarketing).
Dizziness, lightheadedness, insomnia (5% to 10%); depression, anxiety, irritability, hallucinations, confusion, headache, somnolence, nervousness, abnormal dreams, agitation (1% to 5%); coma, stupor, delusions, aggressive behavior, paranoid reaction, manic reaction, involuntary muscle contractions, abnormal gait, paresthesia, EEG changes, tremor, (postmarketing).
Pruritus, diaphoresis (postmarketing).
Dry nose (1% to 5%); keratitis, mydriasis (postmarketing).
Nausea (5% to 10%); dry mouth, constipation, diarrhea (1% to 5%); dysphagia (postmarketing).
Elevated CPK, BUN, serum creatinine, alkaline phosphatase, LDH, bilirubin, glucose tolerance test, AST, ALT.
Acute respiratory failure, pulmonary edema, tachypnea (postmarketing).
Ataxia, livedo reticularis, peripheral edema, fatigue (1% to 5%); allergic reactions (including anaphylactic reactions, edema, and fever), neuroleptic malignant syndrome (postmarketing).
Category C .
Excreted in breast milk.
Safety and efficacy in newborns and infants under 1 yr not established.
Decreased dosage is necessary.
Reduced dose is required in renal function impairment.
Use with caution.
Use with caution in patients with a history of recurrent eczematoid rash, psychosis, or severe psychoneurosis not controlled by chemotherapeutic agents.
CHF has developed in patients taking amantadine.
Because amantadine has anticholinergic effects and may cause mydriasis, do not give to patients with untreated angle-closure glaucoma.
Neuroleptic malignant syndrome may occur in association with dose reduction or withdrawal of amantadine therapy.
Reduced dose is necessary in patients with prior seizure disorders, including epilepsy.
Successful suicide and suicide attempts have been reported in patients with and without a history of psychiatric illness.
Death, cardiac, respiratory, renal, or CNS toxicity, cardiac dysfunction (including arrhythmia, tachycardia, and hypertension), pulmonary edema, respiratory distress (including adult respiratory distress syndrome), renal dysfunction (including increased BUN, decreased Ccr and renal insufficiency), CNS effects (including insomnia, anxiety, agitation, aggressive behavior, hypertonia, hyperkinesias, ataxia, gait abnormality, tremor, confusion, disorientation, depersonalization, fear, delirium, hallucinations, psychotic reactions, lethargy, somnolence, and coma), seizures, hyperthermia.
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