Disopyramide and Quinidine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Quinidine
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
An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest)
Interaction Deep Dive
Class Ia antiarrhythmic agents may prolong the QT interval and worsen arrhythmias, possibly leading to ventricular tachycardia and ventricular fibrillation. Concomitant use of a class Ia antiarrhythmic agent (eg, disopyramide, procainamide, quinidine) with another class Ia agent may lead to additive effects and excessive prolongation of conduction, serious negative inotropic effects, or hypotension, especially in patients with current or history of cardiac decompensation. Reserve such concomitant therapy for patients with life-threatening arrhythmias who are unresponsive to single-agent therapy. Carefully monitor patients during treatment1234.
Why it happens (mechanism)
Additive cardiac effects
Literature reports
1 report — tap to read
a) Concomitant administration of procainamide and quinidine was reported to result in significant increases in procainamide and NAPA (N-acetylprocainamide) serum concentrations in a 53-year-old male with ventricular arrhythmias 5. The speculated mechanism of the interaction was interference of the renal elimination of procainamide by quinidine 2.
Common questions
Can I take Disopyramide and Quinidine 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 Disopyramide and Quinidine 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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Disopyramide or Quinidine 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: disopyramide phosphate oral capsules, disopyramide phosphate oral capsules. Teva Pharmaceuticals USA, Inc. (per DailyMed), North Wales, PA, 2015. DailyMed
- Product Information: quinidine gluconate oral extended release tablets, quinidine gluconate oral extended release tablets. Sun Pharmaceutical Industries, Inc. (per DailyMed), Cranbury, NJ, 2014. DailyMed
- Product Information: procainamide HCl intravenous injection solution, intramuscular injection solution, procainamide HCl intravenous injection solution, intramuscular injection solution. Hospira, Inc. (per DailyMed), Lake Forest, IL, 2013. DailyMed
- Product Information: quinidine gluconate intravenous injection solution, quinidine gluconate intravenous injection solution. Lilly USA, LLC (per DailyMed), Indianapolis, IN, 2012. DailyMed
- Hughes B, Dyer JE, & Schwartz AB: Increased procainamide plasma concentrations caused by quinidine: a new drug interaction. Am Heart J 1987; 114:908-909. PubMed
Keep reading about Quinidine
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.
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