Drug interactions
Mirabegron + Tamoxifen
Severity: Moderate
Mirabegron 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
Mirabegron is a moderate inhibitor of CYP2D6, which is needed to convert tamoxifen into its highly active metabolite endoxifen. Reduced conversion could in theory lower the antiestrogenic effect of tamoxifen, but the clinical significance has not been established.
What this interaction means in plain words
Mirabegron 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.
Mirabegron belongs to Genitourinary; Tamoxifen belongs to Endocrine.
Why it happens
Mirabegron inhibits CYP2D6, which may decrease formation of endoxifen from tamoxifen.
What to do
Where possible, choose an overactive bladder agent that does not inhibit CYP2D6, such as an antimuscarinic with weak CYP2D6 effect or vibegron. If the combination is needed, monitor for loss of tamoxifen efficacy.
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 Mirabegron
- Digoxin + Mirabegron Major
- Flecainide + Mirabegron Major
- Mirabegron + Propafenone Major
- Mirabegron + Thioridazine Major
- Amitriptyline + Mirabegron Moderate
- Amoxapine + Mirabegron Moderate
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 Mirabegron with Tamoxifen?
MediHelp rates the interaction as moderate. Mirabegron 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. Mirabegron is a moderate inhibitor of CYP2D6, which is needed to convert tamoxifen into its highly active metabolite endoxifen. Reduced conversion could in theory lower the antiestrogenic effect of tamoxifen, but the clinical significance has not been established.
How serious is the interaction between Mirabegron 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 overactive bladder agent that does not inhibit CYP2D6, such as an antimuscarinic with weak CYP2D6 effect or vibegron. If the combination is needed, monitor for loss of tamoxifen efficacy.
What other medicines interact with Mirabegron?
MediHelp also lists interactions of Mirabegron with, for example, Digoxin, Flecainide, Propafenone. The full list is on the Mirabegron page.
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