Tetrabenazine, marketed as Xenazine, is a medication specifically indicated for the treatment of chorea associated with Huntington’s disease. It functions as a vesicular monoamine transporter 2 (VMAT2) inhibitor, depleting monoamines like dopamine in the brain to reduce involuntary movements.
About Tetrabenazine Tablets
Tetrabenazine tablets, commonly known by the brand name Xenazine, belong to a class of drugs called VMAT2 inhibitors. These tablets are designed to address hyperkinetic movement disorders, particularly chorea—the uncontrollable, jerking movements that characterize Huntington’s disease (HD). Huntington’s disease is a progressive neurodegenerative disorder caused by a mutation in the huntingtin gene, leading to the breakdown of nerve cells in the brain.
Unlike treatments that cure the underlying disease, Tetrabenazine provides symptomatic relief by modulating neurotransmitter activity in the basal ganglia, a brain region crucial for movement control. It has been used internationally for decades and received FDA approval on August 15, 2008, as the first drug specifically for HD chorea in the United States.
The tablets are typically available in 12.5 mg and 25 mg strengths, allowing for precise dose titration. Patients should swallow them whole with water, and they can be taken with or without food, though consistency in administration timing aids in maintaining steady blood levels.
Key facts
- Tetrabenazine is used to treat chorea (involuntary movements) in Huntington’s disease.
- About 5 in 10 people experience drowsiness when starting treatment.
- Tetrabenazine tablets usually improve symptoms within 1-2 weeks.
- Common side effects include drowsiness, fatigue, nausea, and depression.
- The maximum recommended daily dose is 100 mg, adjusted based on CYP2D6 metabolism.
When to take Tetrabenazine Tablets
Tetrabenazine should be initiated at a low dose, typically 12.5 mg once daily, and titrated weekly based on response and tolerability. Dosing is individualized, often divided into 2-3 administrations per day to minimize peak-related side effects. Morning doses may be lower if sedation is prominent.
For patients requiring more than 37.5-50 mg/day, CYP2D6 genotyping is recommended to classify them as poor, intermediate, extensive, or ultra-rapid metabolizers, guiding maximum dosing. Poor metabolizers should not exceed 50 mg/day, while extensive metabolizers may go up to 100 mg/day.
| Patient Type | Starting Dose | Titration | Max Daily Dose |
|---|---|---|---|
| All patients | 12.5 mg once daily | Increase by 12.5 mg weekly | 100 mg (divided) |
| Poor CYP2D6 metabolizers | 12.5 mg once daily | Slow titration | 50 mg |
| Extensive metabolizers | 12.5 mg once daily | Weekly increases | 100 mg |
Do not abruptly stop Tetrabenazine; taper gradually to avoid chorea rebound.
How to take Tetrabenazine Tablets
Follow your doctor’s instructions precisely. Start with 12.5 mg daily for the first week, then increase to 12.5 mg twice daily if tolerated. Continue weekly increments of 12.5 mg until optimal response or side effects occur. Divide higher doses into three parts, with no single dose exceeding 37.5 mg for most patients.
Take with water, with or without food. If you miss a dose, take it as soon as remembered unless close to the next dose—do not double up. Store at room temperature away from moisture.
Common questions about Tetrabenazine Tablets
How long does it take to work?
Symptoms often improve within 1-2 weeks, with peak effects seen after dose stabilization. Clinical studies show rapid onset, with visible chorea reduction within 90 minutes in some cases.
Do I need to avoid alcohol?
Yes, alcohol can enhance sedation and impair liver function. Avoid combining with alcohol.
Cautions
Tetrabenazine carries a boxed warning for depression and suicidality, as it increases risk due to dopamine depletion. Monitor for mood changes, especially in HD patients prone to psychiatric issues. Discontinue if depression or suicidal thoughts emerge.
Other cautions include:
- Parkinsonism or worsening movements: May occur; reduce dose if persistent.
- Neuroleptic malignant syndrome (NMS): Rare but serious; watch for fever, rigidity, confusion.
- QT prolongation: Avoid in patients with heart rhythm issues; monitor ECG if needed.
- Sedation: Common; avoid driving until effects known.
- Pregnancy/Breastfeeding: Limited data; use only if benefits outweigh risks.
Side effects
Most side effects are dose-related and improve with reduction. Clinical trials reported:
| Side Effect | Frequency | Management |
|---|---|---|
| Sedation/Somnolence | Common (up to 50%) | Lower morning dose; take at bedtime |
| Fatigue | Common | Dose adjustment |
| Depression | Common/Serious | Monitor closely; seek help immediately |
| Akathisia/Restlessness | Common | Dose reduction |
| Nausea | Common | Take with food |
Serious effects include suicidal ideation, NMS, and severe allergic reactions. Report any unusual symptoms promptly.
Interactions with other medicines
Tetrabenazine is metabolized by CYP2D6; inhibitors (e.g., fluoxetine, paroxetine) increase levels, requiring dose reduction. Avoid strong CYP2D6 inducers. Do not combine with reserpine or MAOIs—wait 14 days. Use caution with other sedatives, antipsychotics, or QT-prolonging drugs.
- Strong CYP2D6 inhibitors: Reduce Tetrabenazine dose by 50%.
- Alcohol/CNS depressants: Increased sedation.
- Antipsychotics: Additive effects on movement/extrapyramidal symptoms.
Other medicines and food
Inform your doctor of all medications, including over-the-counter and herbal supplements. Grapefruit juice may affect metabolism minimally. Maintain a balanced diet; no specific food restrictions, but consistent timing helps.
Serious side effects and what to do
Seek immediate medical help for:
- Suicidal thoughts or severe depression.
- Muscle rigidity, high fever, confusion (NMS).
- Fast/irregular heartbeat, dizziness (QT issues).
- Uncontrolled movements worsening.
For non-emergencies like persistent nausea or sedation, contact your prescriber for dose adjustment.
Pregnancy and breastfeeding
Tetrabenazine is Pregnancy Category C; animal studies show risks, human data limited. Use only if essential. It is unknown if excreted in breast milk—avoid breastfeeding or discontinue drug.
Driving and using machinery
Sedation impairs alertness; do not drive or operate machinery until you know its effects. Sedation peaks 1-4 hours post-dose and may last several hours.
Diabetes, eyesight, and other conditions
No direct effects on diabetes or eyesight. Use caution in hepatic impairment (contraindicated in severe cases) or cardiac issues. Regular monitoring recommended for HD patients.
Living with Huntington’s Disease
Huntington’s disease affects movement, cognition, and mood. Tetrabenazine targets chorea but not other symptoms. Combine with physical therapy, speech therapy, and psychological support. Genetic counseling for families is advised.
Healthcare team roles
- Neurologist: Prescribes and monitors treatment.
- Pharmacist: Advises on dosing/interactions.
- Nurse: Educates on administration/side effects.
- Therapist: Manages functional impacts.
Analogue medicines
Alternatives include deutetrabenazine (Austedo) and valbenazine, also VMAT2 inhibitors with similar profiles but potentially different side effect burdens.
Patient Leaflet(s)
Refer to the official Xenazine Medication Guide for full details on risks, especially depression/suicidality.
Further reading & references
Explore clinical studies showing 23-42% chorea reduction in HD patients.
Frequently Asked Questions (FAQs)
What is Tetrabenazine used for?
It treats chorea in Huntington’s disease by depleting dopamine.
Can Tetrabenazine cause depression?
Yes, it carries a boxed warning for depression and suicidal thoughts; monitor closely.
What is the maximum dose of Tetrabenazine?
100 mg/day for most, 50 mg for poor metabolizers, after CYP2D6 testing.
How quickly does Xenazine work?
Improvements often within days to weeks; rapid onset in studies.
Is Tetrabenazine safe to stop suddenly?
No, taper to prevent chorea rebound.
References
- Tetrabenazine (Xenazine) for Huntington’s Disease Chorea — PMC/NCBI. 2009-07-01. https://pmc.ncbi.nlm.nih.gov/articles/PMC2730806/
- Tetrabenazine (Xenazine): Uses, Side Effects, Interactions — WebMD. 2023-01-01. https://www.webmd.com/drugs/2/drug-151522/tetrabenazine-oral/details
- Tetrabenazine: MedlinePlus Drug Information — MedlinePlus/NIH. 2024-01-01. https://medlineplus.gov/druginfo/meds/a618009.html
- Tetrabenazine: Uses, Interactions, Mechanism of Action — DrugBank. 2024-01-01. https://go.drugbank.com/drugs/DB04844
- XENAZINE® (tetrabenazine) tablets Prescribing Information — FDA. 2015-01-01. https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/021894s010lbl.pdf
- Xenazine Medication Guide — Lundbeck. 2023-01-01. https://www.lundbeck.com/upload/us/files/pdf/products/xenazine_mg_us_en.pdf
