Tetrabenazine
XENAZINE
What it isReversible VMAT2 inhibitor that depletes presynaptic monoamines; Huntington chorea.
Why this oneIt is inexpensive but produces less even exposure and more CYP2D6 sensitivity than deutetrabenazine.
What limits itDepression and suicidality are boxed risks in Huntington disease; sedation, parkinsonism, and QT prolongation also matter.
FDA-approved for
- Huntington chorea (2008)
Off-label
- tardive dyskinesia
- tics in Tourette syndrome
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Chorea associated with Huntington's disease | Adults | 12.5 mg QD (morning), then 25 mg/day (12.5 mg BID) week 2 | Individualized tolerated dose; 37.5–50 mg/day given TID | 50 mg/day (max single 25 mg); >50 mg/day requires CYP2D6 genotyping — EM/IM up to 100 mg/day (max single 37.5 mg), PM up to 50 mg/day (max single 25 mg) |
Titration Increase at weekly intervals by 12.5 mg/day
Renal Undefined
Hepatic Contraindicated in hepatic impairment
Doses 37.5–50 mg/day given TID; maximum single dose 25 mg (37.5 mg in EM/IM)
Instructions
- May be given without regard to food
- With a strong CYP2D6 inhibitor (e.g., fluoxetine, paroxetine, quinidine): do not exceed 50 mg/day and 25 mg single dose
- May discontinue without tapering; re-titrate if interruption exceeds 5 days
- Avoid combining with other QTc-prolonging drugs
Contraindications
- Actively suicidal, or untreated / inadequately treated depression
- Hepatic impairment
- MAOIs (concurrently or within 14 days)
- Taking reserpine (allow ≥20 days after stopping reserpine before starting)
- Taking deutetrabenazine or valbenazine
Cautions
- Neuroleptic malignant syndrome
- Akathisia, restlessness, agitation
- Parkinsonism
- Sedation/somnolence (dose-limiting)
- QTc prolongation
- Hypotension/orthostatic hypotension
- Hyperprolactinemia
Adverse reactions
- Sedation/somnolence
- Insomnia
- Fatigue
- Depression
- Akathisia
- Anxiety
- Nausea
Pregnancy No adequate human data; animal data show increased stillbirths and postnatal mortality — may cause fetal harm
Lactation No data on presence in human milk
⚠ BOXED WARNING
- Depression and suicidality in Huntington disease
Cost, est. cash$3,000–$10,000/month
Generic entry2015
Classes and tags
Clinical profile
Legacy pregnancy categoryUnknown / historical label unavailable
Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.
Mechanism of action: Tetrabenazine ballicule
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QT prolongation
