Amantadine is an antiviral agent. Amantadine also increases dopaminergic activity in the peripheral and central nervous system. Amantadine is recommended for the prophylaxis and therapy of influenza A infections; however, amantadine is not a substitute for vaccination.
In addition, amantadine may be useful in the treatment of Parkinsonism, in the management of multiple sclerosis symptoms, and in combination with interferon for chronic hepatitis C.

Amantadine alone or with levodopa is useful in alleviating parkinsonian symptoms; however, when used alone it does not appear to be as effective as levodopa or trihexyphenidyl.

Onset of action: Within 48 hours
Absorption: Well absorbed
Distribution: Vd: Normal: 3 to 8 L/kg; Renal failure: 5.1 ± 0.2 L/kg
Protein binding: Normal renal function: ~67%; Hemodialysis: ~59%
Metabolism: Not appreciable; small amounts of an acetyl metabolite identified
Bioavailability: Immediate release: 86% to 94%
Half-life elimination:
Normal renal function: 16 ± 6 hours (9 to 31 hours);
Healthy, older (?60 years) males: 29 hours (range: 20 to 41 hours) (Aoki 1988);
End-stage renal disease: 8 days
Time to peak, plasma:
Extended-release capsule: 12 hours (mean; range: 6 to 20 hours);
extended-release tablet: 7.5 hours (median; range: 5.5 to 12 hours);
immediate release: 2 to 4 hours
Excretion: Urine (80% to 90% unchanged) by glomerular filtration and tubular secretion

Hypersensitivity to amantadine;
In Parkinson's disease patients, abrupt discontinuation may result in Parkinsonian crisis.

C

Amantadine is present in breast milk. Amantadine may alter breast milk production or excretion. According to the manufacturer, the decision to breastfeed during therapy should consider the risk of infant exposure, the benefits of breastfeeding to the infant, and benefits of treatment to the mother.

Adverse effects include anticholinergic effects, confusion, disorientation, depression, nervousness, insomnia, and dermatologic reactions.

Adults: Extrapyramidal Reactions: 200-300 mg/day in divided doses for controlling drug-induced extrapyramidal reactions.
Influenza A: 200 mg PO QD or 100 mg PO BID.

Children:
1 to 9 years: 4.4 to 8.8 mg/kg/day to a maximum of 150 mg/day QD or BID.
10 years and older: 100 mg BID;
however, for children weighing less than 40 kg, prescribing 5 milligrams/kilogram/day, regardless of age, is advisable.

Dose adjustment in renal insufficiency patients
ClCr 30-50ml/min：Suggested maintenance dose 100 mg QD.
ClCr 15-29ml/min：Suggested maintenance dose 100 mg QOD
ClCr <15ml/min：Suggested maintenance dose 200 mg every 7 days.