Disopyramide and Tetrabenazine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Tetrabenazine
Disopyramide
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
Increased risk of QT interval prolongation
Interaction Deep Dive
Tetrabenazine causes a small increase in the corrected QT interval. As the degree of prolongation increases, QT prolongation can develop into torsade de pointes-type VT. The concomitant use of tetrabenazine with other class IA antiarrhythmic drugs known for QT prolongation (eg, procainamide, hydroquinidine, disopyramide) should be avoided1. In a randomized, double-blind, placebo controlled crossover study of healthy subjects, the effect of a single 25 mg or 50 mg dose of tetrabenazine on the QT interval was studied with moxifloxacin as a positive control. The 50 mg dose of tetrabenazine caused an approximate 8 millisecond mean increase in QT 1.
Why it happens (mechanism)
Additive effects on QT interval prolongation
Common questions
Can I take Disopyramide and Tetrabenazine together?
Increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Disopyramide and Tetrabenazine 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 Disopyramide or Tetrabenazine 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 (1)
- Product Information: XENAZINE(R) oral tablets, tetrabenazine oral tablets. Prestwick Pharmaceuticals,Inc, Washington, DC, 2008. DailyMed
Keep reading about Tetrabenazine
Keep reading about Disopyramide
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist