Drug interactions
Flecainide + Vemurafenib
Severity: Major
Flecainide and Vemurafenib: major interaction.
Last updated
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
Vemurafenib may alter the exposure of CYP2D6 substrates and prolongs the QT interval. Flecainide has a narrow therapeutic index and is proarrhythmic, so increased levels and additive QT effects may lead to serious arrhythmia.
What this interaction means in plain words
Flecainide and Vemurafenib 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.
Flecainide belongs to Cardiovascular; Vemurafenib belongs to Oncology.
Why it happens
Vemurafenib may inhibit CYP2D6, increasing flecainide levels, together with additive effects on cardiac repolarization and conduction.
What to do
Avoid if possible. If coadministered, monitor ECG, electrolytes and flecainide levels and consider reducing the flecainide dose.
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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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 Vemurafenib
Frequently asked questions
Can I take Flecainide with Vemurafenib?
MediHelp rates the interaction as major. Flecainide and Vemurafenib 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. Vemurafenib may alter the exposure of CYP2D6 substrates and prolongs the QT interval. Flecainide has a narrow therapeutic index and is proarrhythmic, so increased levels and additive QT effects may lead to serious arrhythmia.
How serious is the interaction between Flecainide and Vemurafenib?
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. If coadministered, monitor ECG, electrolytes and flecainide levels and consider reducing the flecainide dose.
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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