Drug interactions
Procainamide + Quinidine
Severity: Major
Procainamide and Quinidine: major interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Both are class IA antiarrhythmics that prolong the QT and QRS intervals. Combined use increases the risk of torsades de pointes and conduction block.
What this interaction means in plain words
Procainamide and Quinidine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Additive sodium and potassium channel blockade causing QT and QRS prolongation.
What to do
Avoid combining two class IA agents; if it is unavoidable, use close ECG monitoring in a monitored setting.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
Frequently asked questions
Can I take Procainamide with Quinidine?
MediHelp rates the interaction as major. Procainamide and Quinidine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both are class IA antiarrhythmics that prolong the QT and QRS intervals. Combined use increases the risk of torsades de pointes and conduction block.
How serious is the interaction between Procainamide and Quinidine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid combining two class IA agents; if it is unavoidable, use close ECG monitoring in a monitored setting.
What other medicines interact with Quinidine?
MediHelp also lists interactions of Quinidine with, for example, Adagrasib, Arsenic trioxide, Artemether / lumefantrine. The full list is on the Quinidine page.
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