Amantadine for Vascular Parkinsonism in the Elderly
Introduction to Amantadine Use
- The American Geriatrics Society recommends that the daily dose of amantadine in patients ≥65 years should not exceed 100 mg due to dose-dependent toxicity 1
Dosing and Renal Considerations
- The National Institute on Aging suggests that women and individuals with renal impairment may require a dose reduction below 100 mg/day to minimize severe CNS toxicity 1
- The Centers for Disease Control and Prevention recommend that amantadine dose should be reduced in patients with creatinine clearance ≤50 mL/min/1,73m² to prevent drug accumulation 1
CNS Toxicity and Monitoring
- The MMWR Recommendations and Reports warn that concentrations >3000 ng/mL are associated with myoclonus, hallucinations, and delirium, even in patients without prior psychiatric symptoms 2
- The Praxis Medical Insights guideline advises monitoring for CNS toxicity (confusion, hallucinations, agitation) especially during the first week of treatment 1
Special Considerations
- The American College of Clinical Pharmacology recommends verifying renal function before initiating amantadine and considering dose reduction in patients with a history of seizures or psychiatric disorders 1, 2
- The guideline suggests that if amantadine is considered for off-label use, the dose should be initiated at 100 mg/day and reduced further if necessary, with close monitoring for toxicity 1