Tetrabenazine and Dolasetron: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Dolasetron
Tetrabenazine
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increased risk of QT interval prolongation and torsade de pointes
Interaction Deep Dive
Due to the potential for additive effects on the QT interval and increased risk of torsade de pointes, concomitant use of tetrabenazine with dolasetron should be avoided21. However, if concomitant use is required, the patient should be closely monitored for prolongation of the QT interval.
Why it happens (mechanism)
Additive effects on QT interval prolongation
Literature reports
1 report — tap to read
a) In a randomized, double-blind, placebo controlled crossover study of healthy subjects, a mean increase in QT interval was 9 milliseconds (90% confidence interval, 5 to 10. 4 milliseconds) after a single 50 mg dose of tetrabenazine (moxifloxacin as a positive control) 2. For dolasetron, QT prolongation appears to be associated with concentrations of hydrodolasetron. Following a single IV dose of 1.8 mg/kg to pediatric and adult cancer patients, the mean predicated increase (95% upper confidence bound) in QT intervals were 22.5 milliseconds (23.9 milliseconds) and 21.2 milliseconds (22.6 milliseconds). The mean maximum differences in QT from placebo after baseline-correction were 14.1 milliseconds (95% upper confidence bound, 16.1 milliseconds) and 36.6 milliseconds (95% upper confidence bound, 38.6 milliseconds) for 100 mg and 300 mg, respectively, of dolasetron IV in a controlled crossover study (n=80) with 14 measurements over 24 hours. 1.
Common questions
Can I take Tetrabenazine and Dolasetron together?
An increased risk of QT interval prolongation and torsade de pointes Always confirm with your pharmacist or prescriber before making any change.
How serious is the Tetrabenazine and Dolasetron interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Tetrabenazine or Dolasetron need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (2)
- Product Information: ANZEMET(R) IV injection, dolasetron mesylate IV injection. Sanofi-Aventis U.S. LLC (per FDA), Bridgewater, NJ, 2011.
- Product Information: XENAZINE(R) oral tablets, tetrabenazine oral tablets. Lundbeck Inc. (per FDA), Deerfield, IL, 2011. DailyMed
Keep reading about Dolasetron
Keep reading about Tetrabenazine
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