Home Drug Guide Amantadine

Drug Guide

Generic Name

Amantadine

Brand Names Symmetrel

Classification

Therapeutic: Antiviral and antiparkinson agent

Pharmacological: sympathomimetic agent, dopamine agonist

FDA Approved Indications

Prevention and treatment of influenza A infections
Parkinson's disease
Extrapyramidal symptoms caused by neuroleptic drugs

Mechanism of Action

Amantadine inhibits viral replication by blocking the uncoating of Influenza A virus. In Parkinson's disease, it enhances dopamine release and blocks dopamine reuptake, increasing dopaminergic activity.

Dosage and Administration

Adult: 100 mg twice daily for Parkinson's; 200 mg daily for influenza prophylaxis

Pediatric: Not generally recommended for children under 12 for influenza; dose varies for Parkinson's

Geriatric: Start at lower doses and monitor closely due to renal function

Renal Impairment: Dose reduction required, as amantadine is renally excreted

Hepatic Impairment: Use with caution; no specific dose adjustment

Pharmacokinetics

Absorption: Well absorbed orally

Distribution: Widely distributed, crosses blood-brain barrier

Metabolism: Minimal hepatic metabolism

Excretion: Primarily renally excreted unchanged

Half Life: 10-14 hours in individuals with normal renal function

Contraindications

Glaucoma, history of seizures, hypersensitivity

Precautions

Use with caution in patients with seizure disorders, heart failure, or renal impairment. Monitor for neuropsychiatric side effects.

Adverse Reactions - Common

Dizziness, insomnia, nausea, dry mouth (Common)
Hallucinations, confusion, livedo reticularis, peripheral edema (Less common)

Adverse Reactions - Serious

Seizures, neuropsychiatric disturbances, allergic reactions (Rare)

Drug-Drug Interactions

Caution with other CNS-active drugs, anticholinergics, and antihypertensives

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor renal function, mental status, and neurological symptoms.

Diagnoses:

Risk for neuropsychiatric effects, risk for falls due to dizziness

Implementation: Administer as prescribed, monitor for adverse effects, educate patient.

Evaluation: Assess symptom control, monitor for adverse reactions, especially neuropsychiatric symptoms.

Patient/Family Teaching

Take medication exactly as prescribed.
Report any neuropsychiatric symptoms or allergic reactions.
Maintain hydration and good nutrition.
Regular follow-up for renal function and neurological status.

Special Considerations

Black Box Warnings:

Psychosis, hallucinations, and other neuropsychiatric effects are serious and may occur, especially in elderly patients.

Genetic Factors: Genetic variations may influence therapeutic effects and side effects.

Lab Test Interference: May interfere with certain diagnostic tests, including urine assays.

Overdose Management

Signs/Symptoms: CNS disturbances including hallucinations, seizures, agitation, and coma.

Treatment: Supportive care, activated charcoal if ingestion was recent, and hospitalization for symptomatic management.

Storage and Handling

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

Stability: Stable under recommended storage conditions.