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Amantadine is a prescription medicine with antiparkinsonian and antiviral actions. Immediate-release amantadine hydrochloride capsules are approved for Parkinson disease and related parkinsonian syndromes, drug-induced extrapyramidal reactions, and prevention or treatment of illness caused by susceptible influenza A virus strains. The medicine is cleared mainly through the kidneys, so reduced kidney function requires dose adjustment.
read more about amantadine ...The exact antiparkinsonian mechanism is not fully established. Amantadine has weak noncompetitive activity at N-methyl-D-aspartate receptors and also affects dopamine pathways. These actions are thought to contribute to improvement in tremor, stiffness, slowed movement, and other parkinsonian symptoms. Its antiviral action is separate and interferes with an early stage of influenza A viral replication.
Immediate-release amantadine capsules are labeled for idiopathic Parkinson disease, postencephalitic parkinsonism, selected symptomatic parkinsonism, and drug-induced extrapyramidal reactions. The same formulation also carries indications for prevention and treatment of uncomplicated respiratory illness caused by susceptible influenza A strains. The label retains influenza A indications, while current CDC guidance does not recommend amantadine for seasonal influenza in the United States due widespread resistance.
For Parkinsonism, the usual adult dose is 100 mg twice daily when amantadine is used alone. Selected patients start at 100 mg once daily before increasing. Influenza A dosing differs by age, and adults commonly receive 200 mg daily. Kidney impairment requires lower or less frequent dosing since amantadine can accumulate when renal clearance falls.
Amantadine can cause dizziness, insomnia, nausea, confusion, hallucinations, low blood pressure, swelling, and livedo reticularis. Serious concerns include suicidal thoughts or behavior, seizures, neuroleptic malignant syndrome after abrupt dose reduction or withdrawal, and worsening heart failure or edema. Kidney impairment raises exposure, so renal dosing is especially important in older adults and patients with reduced kidney function.
Yes. Immediate-release amantadine is approved for Parkinson disease and selected related parkinsonian conditions.
Yes. It has antiviral activity against susceptible influenza A strains, but current CDC guidance does not recommend it for seasonal influenza in the United States due widespread resistance.
Yes. Reduced kidney function slows amantadine clearance, so the dose or dosing interval is changed according to renal function.
Rapid dose reduction or abrupt withdrawal can trigger serious reactions, including symptoms resembling neuroleptic malignant syndrome.
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Amantadine. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK499953/. Date Accessed September 11, 2026.
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