Quinidine and Arsenic Trioxide: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Quinidine
Arsenic Trioxide
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 cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest)
Interaction Deep Dive
Class Ia antiarrhythmics have been shown to prolong the QTc interval at the recommended therapeutic dose. Even though no formal drug interaction studies have been done, the coadministration of arsenic trioxide and other drugs known to prolong the QTc interval, including Class Ia antiarrhythmics, is not recommeded2345.
Why it happens (mechanism)
Additive cardiac effects
Literature reports
1 report — tap to read
a) QT/QTc prolongation should be expected during treatment with arsenic trioxide and torsade de pointes as well as complete heart block has been reported. Over 460 ECG tracings from 40 patients with refractory or relapsed APL treated with arsenic trioxide were evaluated for QTc prolongation. Sixteen of 40 patients (40%) had at least one ECG tracing with a QTc interval greater than 500 msec. Prolongation of the QTc was observed between 1 and 5 weeks after arsenic trioxide infusion, and then returned towards baseline by the end of 8 weeks after arsenic trioxide infusion. In these ECG evaluations, women did not experience more pronounced QT prolongation than men, and there was no correlation with age 1.
Common questions
Can I take Quinidine and Arsenic Trioxide together?
An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Quinidine and Arsenic Trioxide 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 Quinidine or Arsenic Trioxide 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 (5)
- Product Information: Trisenox(R), arsenic trioxide. Cell Therapeutics, Inc. Seattle, WA, 2001. DailyMed
- Product Information: Trisenox(R), arsenic trioxide injection. Cell Therapeutics, Inc. Seattle, WA, 2001. DailyMed
- Product Information: Procanbid(R), procainamide extended release tablets. Warner-Lambert Co, Morris Plains, NJ, 2000.
- Product Information: Quinaglute Dura-tabs(R), quinidine gluconate. Berlex Laboratories, Wayne, NJ, 1999. DailyMed
- Desai JM, Scheinman MM, Hirschfeld D, et al: Cardivascular collapse associated with disopyramide therapy. Chest 1981; 79:545-551.
Keep reading about Quinidine
Keep reading about Arsenic Trioxide
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.
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