Drug interactions
Dofetilide + Venlafaxine
Severity: Major
Dofetilide and Venlafaxine: major interaction.
Last updated Sources: UK SmPC
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
Dofetilide has a narrow therapeutic window for QT prolongation and torsades de pointes. Venlafaxine can also prolong the QT interval, particularly in overdose, and may add to the arrhythmia risk.
What this interaction means in plain words
Dofetilide 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.
Dofetilide belongs to Cardiovascular; Venlafaxine belongs to Central Nervous System.
Why it happens
Additive QT prolongation, with dofetilide blocking the hERG potassium current.
What to do
Avoid if possible, or use an alternative antidepressant with less QT effect. If combined, monitor ECG QTc and electrolytes closely, especially at dofetilide initiation.
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
- Efexor XL 150 mg hard prolonged release capsules - SmPC sections 4.3/4.5 (names the partner; "nal products should be avoided (see section 4.4). Relevant classes include: • class Ia and III antiarrhythmics (e.g., quinidine, amiodarone, sotalol, dofetilide") — electronic medicines compendium (UK SmPC)
Other interactions of Venlafaxine
- Isocarboxazid + Venlafaxine Contraindicated
- Methylene blue + Venlafaxine Contraindicated
- Phenelzine + Venlafaxine Contraindicated
- Procarbazine + Venlafaxine Contraindicated
- Rasagiline + Venlafaxine Contraindicated
- Safinamide + Venlafaxine Contraindicated
Other interactions of Dofetilide
- Amiodarone + Dofetilide Contraindicated
- Amisulpride + Dofetilide Contraindicated
- Amlodipine-hydrochlorothiazide-valsartan + Dofetilide Contraindicated
- Amlodipine-olmesartan-hydrochlorothiazide + Dofetilide Contraindicated
- Candesartan-hydrochlorothiazide + Dofetilide Contraindicated
- Captopril-hydrochlorothiazide + Dofetilide Contraindicated
Frequently asked questions
Can I take Dofetilide with Venlafaxine?
MediHelp rates the interaction as major. Dofetilide 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. Dofetilide has a narrow therapeutic window for QT prolongation and torsades de pointes. Venlafaxine can also prolong the QT interval, particularly in overdose, and may add to the arrhythmia risk.
How serious is the interaction between Dofetilide 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 if possible, or use an alternative antidepressant with less QT effect. If combined, monitor ECG QTc and electrolytes closely, especially at dofetilide initiation.
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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