Drug interactions
Flecainide + Tetrabenazine
Severity: Major
Flecainide and Tetrabenazine: 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
Tetrabenazine prolongs the QTc interval modestly, and flecainide can cause proarrhythmia and conduction slowing. Combined use may increase the risk of torsade de pointes. Flecainide is also a CYP2D6 substrate and tetrabenazine metabolites are CYP2D6-dependent, adding complexity.
What this interaction means in plain words
Flecainide and Tetrabenazine 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; Tetrabenazine belongs to Central Nervous System.
Why it happens
Additive effects on cardiac repolarization and conduction.
What to do
Avoid if possible and consider alternatives for chorea or rhythm control. If necessary, monitor ECG and electrolytes and use the lowest effective tetrabenazine 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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References
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 Tetrabenazine
- Dronedarone + Tetrabenazine Contraindicated
- Isocarboxazid + Tetrabenazine Contraindicated
- Linezolid + Tetrabenazine Contraindicated
- Phenelzine + Tetrabenazine Contraindicated
- Pimozide + Tetrabenazine Contraindicated
- Procarbazine + Tetrabenazine Contraindicated
Frequently asked questions
Can I take Flecainide with Tetrabenazine?
MediHelp rates the interaction as major. Flecainide and Tetrabenazine 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. Tetrabenazine prolongs the QTc interval modestly, and flecainide can cause proarrhythmia and conduction slowing. Combined use may increase the risk of torsade de pointes. Flecainide is also a CYP2D6 substrate and tetrabenazine metabolites are CYP2D6-dependent, adding complexity.
How serious is the interaction between Flecainide and Tetrabenazine?
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 and consider alternatives for chorea or rhythm control. If necessary, monitor ECG and electrolytes and use the lowest effective tetrabenazine 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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