Adult Dosing
Huntington's chorea
- Initial Dosing: 12.5 mg PO qam
- Titration:
- After 1 week, increase to 12.5 mg PO bid
- Then may increase by 12.5 mg/day at weekly intervals [Max: 25 mg/dose; 100 mg/day]
- CYP2D6 Poor metabolizers: [Max: 25 mg/dose; 50 mg/day]
- CYP2D6 extensive and intermediate metabolizers: [Max 37.5 mg/dose; 100 mg/day]
- If on strong CYP2D6 inhibitors: Reduce daily dose by 50%
- If stabilized on a strong CYP2D6 inhibitor: Follow dosing recommendations for CYP2D6 poor metabolizers
Resumption of Treatment
- Retitrate if therapy is interrupted for more than 5 days
Note: Doses above 50 mg/day should not be given without CYP2D6 genotyping.
Pediatric Dosing
- Safety and effectiveness in pediatric patients have not been established
See Supplemental Patient Information
- Therapy may increase the risk of depression and suicidal thoughts and behavior (suicidality) in patients with Huntington's disease. Closely monitor for the emergence or worsening of depression, suicidality, or unusual changes in behavior [US Black Box Warning]
- Apprise caregivers of the risk of depression and suicidality and instruct them to report behaviors of concern promptly to the treating physician [US Black Box Warning]
- Administer cautiously in patients with a history of depression or prior suicide attempts or suicidal ideation which are increased in frequency in Huntington's disease [US Black Box Warning]
- Therapy is restricted in patients who are actively suicidal, and in patients with untreated or inadequately treated depression [US Black Box Warning]
- Test for the CYP2D6 gene should be done to determine whether patients are poor metabolizers (PMs) or extensive or intermediate metabolizers before patients are given a daily dose of greater than 50 mg
- Patients may develop Neuroleptic Malignant Syndrome (NMS). Immediately discontinue therapy after early signs and symptoms of NMS. Institute symptomatic treatment and closely monitor patients for other concomitant serious medical problems
- Akathisia, restlessness and agitation have been reported with the therapy. Careful monitoring should be done for such symptoms and if a patient develops akathisia, dose should be reduced or therapy should be discontinued
- Reduce dosage or discontinue tetrabenazine if a patient develops parkinsonism during treatment
- Therapy may cause dysphagia and therefore caution is advised in patients with Huntington's disease at risk for aspiration pneumonia
- Sedation is the most common dose-limiting adverse effect of tetrabenazine. Therefore patients should be advised not to perform activities requiring mental alertness, such as operating a motor vehicle or operating hazardous machinery
- Small increase in the corrected QT interval has been reported with the tetrabenazine use. Avoid use in combination with other drugs that are known to prolong QTc as QT prolongation can lead to development of torsades de pointes-type ventricular tachycardia with the risk increasing as the degree of prolongation increases
- Concomitant use of neuroleptic drugs should be avoided because QTc prolongation, NMS, and extrapyramidal disorders may be exaggerated by such concomitant use
- Cautiously administer in alcoholic patients as concomitant use of alcohol or other sedating drugs may have additive effects and may worsen sedation and somnolence
- Hypotension and orthostatic hypotension have occurred. Closely monitor for vital signs on standing in patients who are vulnerable to hypotension
- Monitor for possible risk of tardive dyskinesia. Drug discontinuation should be considered if signs and symptoms of TD appear in a patient treated with tetrabenazine
Cautions: Use cautiously in
- Poor CYP2D6 metabolizer
- Electrolyte abnormalities
- Neuroleptic malignant syndrome history
- Breast CA
- Tardive dyskinesia
- Hx of depression
- Hx of suicidality attempts
Supplemental Patient Information
- Therapy may increase the risk of patients considering or attempting suicide. Patients and their families should be encouraged to be alert to the emergence of suicidal ideation and should report it immediately to the patient's physician
Pregnancy Category:C
Breastfeeding: Safety undetermined, use not recommended. Manufacturer recommends discontinuation of breastfeeding, or postponing of treatment (taking into account the importance of the drug to the mother).
Drug Name: Xenazine 12.5 MG Oral Tablet
Ingredient(s): Tetrabenazine
Imprint: CL;12;5
Color(s): White
Shape: Round
Size (mm): 7.00
Score: 1
Inactive Ingredient(s): lactose / starch, corn / talc / magnesium stearate
Drug Label Author:
Lundbeck Inc.
DEA Schedule:
Non-Scheduled
Drug Name: Xenazine 25 MG Oral Tablet
Ingredient(s): Tetrabenazine
Imprint: CL;25
Color(s): Yellow
Shape: Round
Size (mm): 7.00
Score: 2
Inactive Ingredient(s): lactose / starch, corn / talc / magnesium stearate / ferric oxide yellow
Drug Label Author:
Lundbeck Inc.
DEA Schedule:
Non-Scheduled
