Usual Adult Dose for Huntington Disease

• Initial Dose: 12.5 mg orally per day once in the morning; increase to 12.5 mg orally twice a day after one week.
• Maintenance Dose: Titrate up slowly at weekly intervals by 12.5 mg daily.
• Maximum Single Dose: 25 mg

Comments:

• Administer doses 37.5 mg/day or greater in a 3 times a day regimen.
• Determine CYP450 2D6 metabolizer status in patients who require doses of greater than 50 mg per day.

Use: Chorea associated with Huntington's disease.

Renal Dose Adjustments

Data not available.

Liver Dose Adjustments

Use is contraindicated.

Dose Adjustments

CYP450 Poor Metabolizers:

• Maximum Single Dose: 25 mg
• Maximum Daily Dose: 50 mg

CYP450 Extensive and Intermediate Metabolizers:

• Maximum Single Dose: 37.5 mg
• Maximum Daily Dose: 100 mg

Concomitant Use with Strong CYP450 2D6 Inhibitors:

• Maximum Single Dose: 25 mg
• Maximum Daily Dose: 50 mg

Occurrence of Adverse Reaction (e.g., akathisia, restlessness, parkinsonism, depression, insomnia, anxiety, sedation): Reduce the dose and consider discontinuing this drug or initiating other treatment (e.g., antidepressants) if events do not resolve.

Treatment Interruption:

• Less than 5 days: Resume treatment at the previous maintenance dose without titration.
• Greater than 5 days: Re-titrate with therapy resumption.

Precautions

US BOXED WARNING:

• This drug can increase the risk of depression and suicidality; close observation for the emergence or worsening of depression, suicidality, or unusual behavior changes should accompany therapy.
• Patients, their families, and caregivers should be informed of the risk and instructed to report concerning behaviors promptly to their healthcare providers.
• Particular caution should be exercised in treating any patient with a history of depression or prior suicide attempts or ideation.
• This drug is contraindicated in patients who are actively suicidal or with untreated or inadequately treated depression.

Safety and efficacy have not been established in patients younger than 18 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available.

Other Comments

Administration Advice:

• Individualize dosage for each patient.
• Take this drug without regard to food.
• May discontinue this drug without tapering.

Storage Requirements:

• Protect from light.

General:

• It is unlikely this drug will be of benefit if there is no improvement after 7 to 10 days at the maximum dose.

Monitoring:

• Signs and symptoms of akathisia, agitation, restlessness, new or worsening depression, suicidality

Patient Advice:

• Avoid alcohol and other sedating drugs during treatment.

Frequently asked questions

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