Amantadine

Antiparkinsonian Drug

Drug class: Dopaminergic Antiparkinsonian Agent

Amantadine（中文：金鋼烷胺）

Common Strengths

• Tablets: 100 mg

Drug Usage

Amantadine is utilized for:

• Treating dyskinesia associated with Parkinson's disease.
• Managing drug-induced extrapyramidal symptoms.

Mechanism of Action

The exact mechanism is not fully understood, but it is believed to:

• Increase dopamine release and inhibit its reuptake.
• Act as a weak NMDA receptor antagonist, which helps in reducing dyskinesia.

Route of Administration

Amantadine is administered orally.

Dosages

• Initial Dose: 100 mg once daily; may be increased based on response.

Side Effects

Frequency	Adverse reactions
Common Side Effects	Dizziness
	Nausea
	Insonia
Serious Side Effects	Congestive heary failure exacerbation
	Severe skin reactions (e.g. rash)
	Neuroleptic malignant syndrome

Pharmacokinetics

• Onset Time: Effects may begin within 2 days, but full benefits can take up to 2 weeks.
• Duration: gnerally lasting 12 to 24 hours.

Drug Precautions

Pregnancy

Amantadine should be used during pregnancy only if clearly needed, as risks vs. benefits must be evaluated.

Breastfeeding

Excretion in breast milk is unknown; caution is advised.

Drug Monitoring Items

• Renal Function
  • Regular assessment of renal function is critical, especially in elderly patients or those with pre-existing renal impairment. Amantadine is predominantly excreted unchanged through the kidneys, and impaired renal function can lead to increased plasma concentrations and prolonged half-life of the drug. Monitoring should include:
    • Serum creatinine and blood urea nitrogen (BUN) levels.
    • Estimated glomerular filtration rate (eGFR).
• Mental Status
  • Patients should be monitored for changes in mental status, including:
    • Hallucinations, delusions, depression, and suicidality.
  • Increased risk of neuroleptic malignant syndrome (NMS) symptoms upon abrupt discontinuation.
• Blood Pressure
  • Blood pressure should be monitored regularly due to the risk of orthostatic hypotension, particularly in older adults.
• Liver Function
  • Liver enzymes (AST and ALT should be checked periodically, especially in patients with liver disease or those experiencing symptoms suggestive of hepatic impairment.
• Seizure Activity
  • For patients with a history of seizures, monitoring for seizure activity is advised as amantadine can lower the seizure threshold.

Drug Interactions

Amantadine may interact with:

• Anticholinergic drugs (increased side effects).
• Dopaminergic agents (potentially enhanced effects).

FAQ

How Should I Take the Tablet?

Take amantadine exactly as prescribed by your healthcare provider, typically with or without food.

What Should I Avoid While Taking?

Avoid alcohol and other CNS depressants while taking amantadine due to increased risk of drowsiness.

What Happens if I Miss a Dose?

Take the missed dose as soon as you remember unless it is close to the time of your next dose. Do not double up on doses.