Drug interactions
Procainamide + Venlafaxine
Severity: Major
Procainamide and Venlafaxine: major interaction.
Last updated Sources: Health Canada product monograph
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
Procainamide is a class IA antiarrhythmic that prolongs the QT interval, and venlafaxine can also lengthen QTc, particularly in overdose or at high doses. Together they increase the chance of torsades de pointes.
What this interaction means in plain words
Procainamide and Venlafaxine 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 QT prolongation from procainamide's potassium and sodium channel effects together with venlafaxine's cardiac effects.
What to do
Avoid combining when possible. If used together, check a baseline and follow-up ECG, keep potassium and magnesium normal, and keep the venlafaxine dose as low as effective.
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 Venlafaxine
- Isocarboxazid + Venlafaxine Contraindicated
- Methylene blue + Venlafaxine Contraindicated
- Phenelzine + Venlafaxine Contraindicated
- Procarbazine + Venlafaxine Contraindicated
- Rasagiline + Venlafaxine Contraindicated
- Safinamide + Venlafaxine Contraindicated
Frequently asked questions
Can I take Procainamide with Venlafaxine?
MediHelp rates the interaction as major. Procainamide and Venlafaxine 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. Procainamide is a class IA antiarrhythmic that prolongs the QT interval, and venlafaxine can also lengthen QTc, particularly in overdose or at high doses. Together they increase the chance of torsades de pointes.
How serious is the interaction between Procainamide and Venlafaxine?
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 when possible. If used together, check a baseline and follow-up ECG, keep potassium and magnesium normal, and keep the venlafaxine dose as low as effective.
What other medicines interact with Venlafaxine?
MediHelp also lists interactions of Venlafaxine with, for example, Isocarboxazid, Methylene blue, Phenelzine. The full list is on the Venlafaxine page.
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