What is the recommended dosing schedule for amantadine (twice-daily) for treating tremors?

Amantadine Dosing for Tremor

For treating tremor with amantadine, the recommended twice-daily dosing is 100 mg twice daily (morning and evening) for adults, with adjustments needed for special populations. 1

Standard Adult Dosing

• The standard adult dosage of amantadine for treating tremor is 200 mg per day, administered as 100 mg twice daily 1
• If central nervous system effects develop with once-daily dosing, splitting the dose into twice daily administration may reduce such complaints 1
• Twice-daily dosing provides more consistent blood levels throughout the day, which is important for symptom control 1

Special Population Considerations

Elderly Patients (65 years and older)

• For persons 65 years of age or older, the daily dosage should be reduced to 100 mg (50 mg twice daily) due to age-related decline in renal function 2, 1
• The lower dose in elderly patients helps minimize the risk of central nervous system side effects while maintaining efficacy 2

Pediatric Dosing

• For children 10-12 years of age, the recommended dosage is 100 mg twice daily 2
• For children 1-9 years of age requiring amantadine, the dosage should be 5 mg/kg/day up to 150 mg in two divided doses 2
• Children weighing less than 40 kg (88 lb) should receive 5 mg/kg/day regardless of age, divided into two doses 2

Renal Impairment Adjustments

• A reduction in dosage is recommended for patients with creatinine clearance <50 mL/min/1.73m² 2
• The drug package insert should be consulted for specific dosage recommendations based on creatinine clearance 2
• Patients with renal impairment should be observed carefully for adverse reactions, and further dose reduction may be necessary 2

Titration and Monitoring

• When initiating therapy, particularly in patients with serious medical illnesses, start with 100 mg daily for the first week 1
• After one to several weeks at 100 mg daily, the dose may be increased to 100 mg twice daily if necessary 1
• Monitor for common side effects including nervousness, anxiety, insomnia, difficulty concentrating, and lightheadedness 2
• Be vigilant for signs of myoclonus following amantadine initiation, which although rare, has been reported as an adverse effect 3

Important Considerations

• Effectiveness for essential tremor may be limited; a randomized controlled trial showed amantadine at 100 mg twice daily was not effective for essential tremor 4
• Benefit may diminish after a few months of treatment; increasing the dose to 300 mg daily (in divided doses) may regain effectiveness in some patients 1
• Temporary discontinuation followed by reinitiation may help regain benefit in patients who experience diminished effectiveness over time 1
• For patients with extrapyramidal symptoms, amantadine has shown promising benefits, though dosing should be carefully monitored 5

Administration Timing

• For twice-daily dosing, administer doses approximately 12 hours apart to maintain consistent blood levels throughout the day 1
• If sleep disturbances occur, avoid taking the second dose too close to bedtime 2