Generic Name

Amantadine Hydrochloride

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Classification

FDA Approved Indications

• Prevention and treatment of influenza A virus infections
• Parkinson's disease (adjunct therapy)
• Drug-induced extrapyramidal symptoms

Mechanism of Action

Amantadine inhibits viral replication by blocking the M2 protein of the influenza A virus, impairing uncoating of viral RNA. In Parkinson's disease, it increases dopamine release and blocks dopamine reuptake, providing antiparkinsonian effects.

Dosage and Administration

Adult: 200 mg per day in divided doses (e.g., 100 mg twice daily); adjust based on response and tolerance

Pediatric: Typically 3-12 years old: 7 mg/kg/day in divided doses (maximum 200 mg/day); use with caution

Geriatric: Start at lower doses (e.g., 100 mg once daily), increase gradually based on response and tolerability

Renal Impairment: Adjust dose according to renal function; e.g., for creatinine clearance <50 mL/min, dose reduction recommended

Hepatic Impairment: No specific adjustments; caution advised

Pharmacokinetics

Absorption: Well absorbed from gastrointestinal tract

Distribution: Widely distributed; crosses blood-brain barrier

Metabolism: Minimal hepatic metabolism

Excretion: Primarily renal excretion unchanged in urine

Half Life: 15-20 hours in healthy adults; longer in renal impairment

Contraindications

• Hypersensitivity to amantadine
• History of seizure disorder

Precautions

• Use with caution in patients with renal impairment, history of psychiatric disorders, or cardiovascular disease. Monitor for confusion, hallucinations, and orthostatic hypotension. Caution during pregnancy and lactation; consult risk-benefit ratio.

Adverse Reactions - Common

• Nausea (Most common)
• Insomnia (Common)
• Dizziness (Common)
• Constipation (Common)

Adverse Reactions - Serious

• Livedo reticularis (skin discoloration) (Rare)
• Neuropsychiatric effects (hallucinations, agitation, confusion) (Rare)
• Seizures (Rare)
• Anaphylaxis (Rare)

Drug-Drug Interactions

• Anticholinergics (may enhance anticholinergic side effects)
• centrally acting agents (additive CNS effects)
• Other drugs affecting renal function

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Take medication exactly as prescribed.
• Report any neuropsychiatric symptoms or skin discoloration.
• Do not stop medication abruptly without consulting your healthcare provider.
• Maintain adequate hydration and report any signs of urinary retention or hallucinations.

Special Considerations

Black Box Warnings:

• Neuropsychiatric adverse reactions, including hallucinations, agitation, and depression, may occur, particularly in elderly patients or those with preexisting psychiatric conditions.

Genetic Factors: None specifically identified.

Lab Test Interference: May cause false positives in certain laboratory tests (e.g., urinary catecholamine tests).

Overdose Management

Signs/Symptoms: CNS stimulation (agitation, hallucinations), orthostatic hypotension, urinary retention, seizures in severe cases.

Treatment: Supportive care, activated charcoal if within 1 hour of ingestion, and symptomatic treatment. Hemodialysis may be considered in severe cases, especially with renal failure.

Storage and Handling

Storage: Store at room temperature, away from moisture and light.

Stability: Stable under recommended conditions; check manufacturer’s instructions for expiration date.