Drug interactions
Propafenone + Tamoxifen
Severity: Moderate
Propafenone and Tamoxifen: moderate 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
Propafenone inhibits CYP2D6, which converts tamoxifen to its highly active metabolite endoxifen. Lower endoxifen exposure could reduce the benefit of tamoxifen in breast cancer treatment.
What this interaction means in plain words
Propafenone and Tamoxifen can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Propafenone belongs to Cardiovascular; Tamoxifen belongs to Endocrine.
Why it happens
CYP2D6 inhibition by propafenone reduces the bioactivation of tamoxifen to endoxifen.
What to do
Where possible choose an antiarrhythmic that does not inhibit CYP2D6 strongly. If the combination is needed, discuss with the oncologist about the choice of endocrine therapy.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Propafenone
- Dofetilide + Propafenone Contraindicated
- Dronedarone + Propafenone Contraindicated
- Nilotinib + Propafenone Contraindicated
- Nirmatrelvir / ritonavir + Propafenone Contraindicated
- Nirmatrelvir + Propafenone Contraindicated
- Pimozide + Propafenone Contraindicated
Other interactions of Tamoxifen
- Amiodarone + Tamoxifen Major
- Anastrozole + Tamoxifen Major
- Bupropion + Tamoxifen Major
- Carbamazepine + Tamoxifen Major
- Cinacalcet + Tamoxifen Major
- Dacomitinib + Tamoxifen Major
Frequently asked questions
Can I take Propafenone with Tamoxifen?
MediHelp rates the interaction as moderate. Propafenone and Tamoxifen can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Propafenone inhibits CYP2D6, which converts tamoxifen to its highly active metabolite endoxifen. Lower endoxifen exposure could reduce the benefit of tamoxifen in breast cancer treatment.
How serious is the interaction between Propafenone and Tamoxifen?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Where possible choose an antiarrhythmic that does not inhibit CYP2D6 strongly. If the combination is needed, discuss with the oncologist about the choice of endocrine therapy.
What other medicines interact with Propafenone?
MediHelp also lists interactions of Propafenone with, for example, Dofetilide, Dronedarone, Nilotinib. The full list is on the Propafenone page.
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