How long does it take for Xenazine (tetrabenazine) to work?
It may take 2 to 3 weeks for you to notice an improvement in your chorea symptoms after you start taking tetrabenazine (Xenazine). Continue to take your medicine as directed by your doctor, even if you do not see improvements right away.
In one study, Xenazine showed a statistically significant effect within three weeks on the Total Chorea Score (an item of the Unified Huntington’s Disease Rating Scale) when compared to a placebo (inactive) treatment (an average reduction of 4 vs. 2 units, respectively).
Xenazine is used to treat the involuntary movements (chorea) of Huntington's disease, but it is not a cure. It also does not treat other symptoms of Huntington's disease, such as thinking or emotional problems.
Contact your healthcare provider if you think the medicine is not working or you have concerns about side effects.
Xenazine Study Overview
In a 12-week long, randomized, placebo-controlled study of 84 patients with chorea of Huntington disease, patients receiving Xenazine started treatment at a dose of 12.5 mg/day or placebo (54 on Xenazine, 30 on placebo). The active drug dose was increased by 12.5 mg at weekly intervals until satisfactory control of chorea was achieved, intolerable side effects occurred, or until a maximal dose of 100 mg/day was reached.
The primary efficacy endpoint was the Total Chorea Score (measured as a change in the chorea score of the Unified Huntington Disease Rating Scale - UHDRS), which ranged from 0 to 4 (with 0 representing no chorea) for 7 different parts of the body (total score ranged from 0 to 28).
Overall, the Total Chorea Scores for Xenazine declined by 5 units during the maintenance phase, which was the average of Week 9 and Week 12 scores vs. baseline scores at the start of the study, compared to a reduction of 1.5 units for the placebo group. The endpoint change of 3.5 units was statistically significant (p<0.0001), and represented a clinically meaningful 24% reduction in chorea severity from baseline (the start of the study).
Percentage of patients achieving reductions of at least 10, 6, and 3 points from baseline to Week 12
- 3 unit reduction: Xenazine 69% vs. 23% placebo
- 6 unit reduction: Xenazine 50% vs. 7% placebo
- 10 unit reduction: Xenazine 19% vs. 3% placebo
A Physician-rated Clinical Global Impression (CGI) favored Xenazine, but measures of functional capacity, cognition and activities of daily living (such as bathing, dressing, eating, toileting) did not fully meet statistical significance.
Study Side Effects
The most commonly reported side effects in at least 10% of patients (Xenazine vs. placebo, respectively) included:
- sedation / somnolence - 31% vs. 3%
- insomnia (trouble sleeping) - 22% vs. 0%
- fatigue - 22% vs. 13%
- depression - 19% vs. 0%
- akathisia (a feeling of restlessness) - 19% vs. 0 %
- anxiety or worsening anxiety - 15% vs. 3%
- fall - 15% vs. 13%
- nausea - 13% vs. 7%
- upper respiratory tract infection - 11% vs. 7%
Over 90% of patients who received Xenazine in the 12-week study experienced one or more adverse reactions (side effects) at any time during the study.
Dose escalation was stopped or the dose was reduced in 28 of 54 (52%) patients randomized to Xenazine due to side effects. SIde effects leading to drug discontinuation included: sedation, akathisia, parkinsonism, depression, anxiety, fatigue and diarrhea.
Xenazine Boxed Warning
Xenazine labeling carries a Boxed Warning for depression and suicidality (suicidal thoughts or actions). A Boxed Warning is the FDA's most stringent safety warning. In all of the HD chorea studies of Xenazine (with 187 patients), one patient committed suicide, one attempted suicide, and six had suicidal ideation.
You should not start taking Xenazine if you have untreated depression or depression that is not well controlled by medicine or have thoughts of suicide. Tell your doctor right away if this applies to you.
Pay close attention to any changes, especially sudden changes, in mood, behaviors, thoughts or feelings. This is especially important when Xenazine is first started and when there are dose changes.
Call the doctor right away if you become depressed or have any of the following symptoms, especially if they are new, worse, or worry you:
- feel sad or have crying spells
- lose interest in seeing your friends or doing things you used to enjoy
- sleep a lot more or a lot less than usual
- feel unimportant
- feel guilty
- feel hopeless or helpless
- are more irritable, angry or aggressive than usual
- are more or less hungry than usual or notice a big change in your body weight
- have trouble paying attention
- feel tired or sleepy all the time
- have thoughts about hurting yourself or ending your life
Note: This is not a complete list of side effects reported with Xenazine use. If you have questions about side effects, contact your doctor right away. You can access a more complete review of Xenazine side effect information here.
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How long does a dose of Xenazine last for chorea?
Chorea symptoms may return within 12 to 18 hours after the last dose of Xenazine is taken. Xenazine has a short half-life of 5 to 7 hours (the time it takes for its blood concentration to reduce by one-half). Within 5 half-lives (25 to 35 hours), most of the drug will be eliminated.
Consistent dosing is important. In one placebo-controlled study when Xenazine treatment was stopped (washout phase), the Total Chorea Score rapidly returned to the baseline levels (symptoms worsened to where they were before the study treatment started) within one week.
How do I take Xenazine?
Xenazine is a tablet you take by mouth. You may take these tablets with or without food. Your doctor will prescribe your dose for you and tell you how to take it. At first, you will start with lower doses then your doctor will increase them over time to help you tolerate any side effects.
You should this medicine exactly as prescribed by your doctor. Follow all instructions on your prescription label. Ask your pharmacist or doctor if you do not understand the directions.
Your doctor may need to change your dose or make other changes to be sure you get the best results. If you need to take higher doses, you may need a simple blood test first.
Do not use Xenazine in larger or smaller amounts or for longer than recommended. You should not stop using this medicine suddenly, or your symptoms may return. Talk to your doctor before you stop taking this medicine.
Call your doctor if your symptoms do not improve or if they get worse. You can access more information about Xenazine dosing here.
This is not all the information you need to know about Xenazine (tetrabenzine) for safe and effective use and does not take the place of your doctor’s directions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.
References
- Huntington Study Group. Tetrabenazine as antichorea therapy in Huntington disease: a randomized controlled trial. Neurology. 2006 Feb 14;66(3):366-72. doi: 10.1212/01.wnl.0000198586.85250.13
- Xenazine (tetrabenazine) prescribing information. Lundbeck Pharmaceuticals. Updated Nov. 2019. Accessed July 18, 2025 at https://www.lundbeck.com/content/dam/lundbeck-com/americas/united-states/products/neurology/xenazine_pi_us_en.pdf
- Yero T, Rey JA. Tetrabenazine (Xenazine), An FDA-Approved Treatment Option For Huntington's Disease-Related Chorea. P T. 2008 Dec;33(12):690-4. PMID: 19750050; PMCID: PMC2730806.
- Suchowersky O (author). Huntington disease: Management. Up to Date. updated: Feb 28, 2023. Accessed July 11, 2023 at https://www.uptodate.com/contents/huntington-disease-management
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