Amantadine is a versatile antiviral and antiparkinsonian agent with a well-established clinical profile. Originally developed as an antiviral medication, its therapeutic applications have expanded to include management of Parkinson’s disease symptoms and drug-induced extrapyramidal symptoms. This synthetic tricyclic amine demonstrates unique pharmacological properties that make it valuable in neurological and infectious disease management. The medication’s dual mechanism of action provides distinct advantages in both antiviral protection and neurological symptom control.

Features

• Chemical name: 1-adamantanamine hydrochloride
• Molecular formula: C₁₀H₁₇N·HCl
• Molecular weight: 187.71 g/mol
• White crystalline powder formulation
• Available in 100 mg capsule and tablet forms
• Oral solution formulation available (50 mg/5 mL)
• Typical packaging: 100-count bottles
• Storage requirements: Room temperature (15-30°C)
• Prescription-only medication status
• Manufactured under strict pharmaceutical GMP standards

Benefits

• Provides effective prophylaxis against influenza A virus infections
• Reduces severity and duration of influenza A symptoms when administered early
• Improves motor symptoms in Parkinson’s disease, including bradykinesia and rigidity
• Helps manage levodopa-induced dyskinesias in Parkinson’s patients
• May provide neuroprotective effects through NMDA receptor antagonism
• Offers convenient once or twice daily dosing regimen for improved compliance

Common use

Amantadine is primarily indicated for the prevention and treatment of respiratory tract infections caused by influenza A virus strains. In neurological practice, it is commonly prescribed for the treatment of Parkinson’s disease, particularly for patients experiencing motor fluctuations and dyskinesias associated with long-term levodopa therapy. The medication is also used off-label for managing fatigue in multiple sclerosis patients and for treating drug-induced extrapyramidal symptoms. Clinical studies have demonstrated its efficacy in reducing influenza transmission in high-risk populations and improving quality of life measures in Parkinson’s disease patients.

Dosage and direction

For influenza prophylaxis in adults: 200 mg once daily or 100 mg twice daily. For influenza treatment: 200 mg initially, followed by 100 mg daily or 100 mg twice daily. For Parkinson’s disease: Initial dose of 100 mg daily, increasing to 100 mg twice daily after one week, with maximum recommended dose of 400 mg daily in divided doses. Elderly patients and those with renal impairment require dose adjustments based on creatinine clearance. Administration with food may minimize gastrointestinal discomfort. The medication should be taken at consistent times daily to maintain stable plasma concentrations.

Precautions

Patients with history of seizures should use amantadine with caution due to potential lowering of seizure threshold. Renal function should be assessed before initiation and monitored during therapy. Elderly patients are more susceptible to central nervous system side effects and require careful dose titration. Patients with congestive heart failure, peripheral edema, or orthostatic hypotension require close monitoring. Abrupt discontinuation may lead to parkinsonian crisis or neuroleptic malignant syndrome in Parkinson’s disease patients. Use caution when operating machinery or driving until response to medication is established.

Contraindications

Hypersensitivity to amantadine or any component of the formulation. Severe renal impairment (creatinine clearance <15 mL/min). Untreated angle-closure glaucoma. History of psychotic disorders without adequate antipsychotic treatment. Pregnancy unless potential benefits outweigh risks. Breastfeeding is generally contraindicated due to secretion in human milk. Concurrent use with live attenuated influenza vaccine. Patients with uncontrolled hypertension or recent myocardial infarction.

Possible side effect

Common side effects include nausea (5-10%), dizziness (5-15%), insomnia (5-10%), and dry mouth (5-15%). Less frequently, patients may experience livedo reticularis (skin discoloration), peripheral edema, orthostatic hypotension, or confusion. Neuropsychiatric effects including anxiety, depression, and hallucinations may occur, particularly in elderly patients. Rare but serious adverse effects include suicidal ideation, seizures, and neuroleptic malignant syndrome upon withdrawal. Cardiac effects including congestive heart failure and arrhythmias have been reported in patients with pre-existing cardiac conditions.

Drug interaction

Amantadine exhibits significant interactions with anticholinergic agents, potentially increasing anticholinergic side effects. Concurrent use with CNS stimulants may exacerbate nervousness, anxiety, and insomnia. QT-prolonging agents may increase risk of cardiac arrhythmias. Memantine should not be co-administered due to similar mechanism of action. Drugs affecting renal excretion (such as triamterene or hydrochlorothiazide) may increase amantadine concentrations. Alcohol may potentiate CNS effects and impair judgment. Dopamine agonists and levodopa may have additive effects requiring dose adjustment.

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is接近 time for the next scheduled dose. In that case, the missed dose should be skipped and the regular dosing schedule resumed. Doubling doses to make up for a missed dose is not recommended. For patients taking twice daily dosing, if remembered within 4 hours of the missed dose, take immediately. If beyond 4 hours, wait until next scheduled dose. Consistent timing is important for maintaining therapeutic levels, particularly for antiviral prophylaxis.

Overdose

Amantadine overdose presents with exaggerated pharmacological effects including severe anxiety, agitation, hallucinations, and cardiac arrhythmias. Massive overdose may lead to convulsions, hyperthermia, and respiratory depression. Management includes gastric lavage if presented within 1-2 hours of ingestion, activated charcoal administration, and supportive care. Acidification of urine may enhance elimination but is contraindicated in patients with renal impairment. Hemodialysis may be effective in removing amantadine from circulation. Cardiac monitoring is essential for 24-48 hours post-overdose. Specific antidotes are not available.

Storage

Store at controlled room temperature between 15-30°C (59-86°F). Protect from light and moisture. Keep container tightly closed. Do not freeze oral solution. Keep out of reach of children and pets. Do not use beyond expiration date printed on packaging. Do not transfer capsules or tablets to other containers unless specifically designed for medication storage. Discard any medication that shows signs of discoloration or physical deterioration.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before starting or changing any medication regimen. The prescribing physician should be consulted for specific dosage recommendations and treatment duration. Individual response to medication may vary based on multiple factors including age, renal function, and concomitant medications. This information is not exhaustive and does not replace comprehensive prescribing information.

Reviews

Clinical studies demonstrate amantadine’s efficacy in influenza prophylaxis with approximately 70-90% protection against symptomatic influenza A infection. In Parkinson’s disease management, studies show significant improvement in Unified Parkinson’s Disease Rating Scale (UPDRS) scores, with particular benefit for dyskinesia reduction. Patient-reported outcomes indicate improved mobility and reduced off-time periods. Some studies suggest potential neuroprotective effects, though this requires further investigation. The medication is generally well-tolerated, though side effect profile necessitates careful patient selection and monitoring. Long-term use requires periodic reassessment of benefit-risk ratio.