Drug interactions
Dofetilide + Flecainide
Severity: Major
Dofetilide and Flecainide: 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 prolongs repolarization strongly and carries a risk of torsades de pointes. Flecainide adds conduction slowing and proarrhythmic effects, so the combined arrhythmic risk rises.
What this interaction means in plain words
Dofetilide and Flecainide 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; Flecainide belongs to Cardiovascular.
Why it happens
Additive effects on cardiac conduction and repolarization (potassium channel blockade plus sodium channel blockade).
What to do
Avoid concurrent use. Dofetilide must be started in a monitored setting with continuous ECG, and the QTc and creatinine clearance must be followed.
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
- Flecainide Acetate 100 mg tablets - SmPC sections 4.3/4.5 (class statement: Class III antiarrhythmics; "Class III antiarrhythmics: If flecainide is given in the presence of") — electronic medicines compendium (UK SmPC)
Other interactions of Flecainide
- Flecainide + Nirmatrelvir Contraindicated
- Flecainide + Nirmatrelvir / ritonavir Contraindicated
- Flecainide + Pimozide Contraindicated
- Flecainide + Ritonavir Contraindicated
- Flecainide + Thioridazine Contraindicated
- Flecainide + Tipranavir 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 Flecainide?
MediHelp rates the interaction as major. Dofetilide and Flecainide 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 prolongs repolarization strongly and carries a risk of torsades de pointes. Flecainide adds conduction slowing and proarrhythmic effects, so the combined arrhythmic risk rises.
How serious is the interaction between Dofetilide and Flecainide?
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 concurrent use. Dofetilide must be started in a monitored setting with continuous ECG, and the QTc and creatinine clearance must be followed.
What other medicines interact with Flecainide?
MediHelp also lists interactions of Flecainide with, for example, Nirmatrelvir, Nirmatrelvir / ritonavir, Pimozide. The full list is on the Flecainide page.
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