Drug interactions
Ribociclib + Tamoxifen
Severity: Major
Ribociclib and Tamoxifen: 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
Ribociclib increases tamoxifen exposure, and both drugs prolong the QT interval. The combination raises the risk of QT prolongation and arrhythmia, and its use is not recommended.
What this interaction means in plain words
Ribociclib and Tamoxifen 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.
Ribociclib belongs to Oncology; Tamoxifen belongs to Endocrine.
Why it happens
Ribociclib inhibits CYP3A4, raising tamoxifen levels, and the two drugs have additive QT-prolonging effects.
What to do
Avoid the combination and use an alternative endocrine agent. If it cannot be avoided, monitor ECG and electrolytes closely.
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 Tamoxifen
- Amiodarone + Tamoxifen Major
- Anastrozole + Tamoxifen Major
- Bupropion + Tamoxifen Major
- Carbamazepine + Tamoxifen Major
- Cinacalcet + Tamoxifen Major
- Dacomitinib + Tamoxifen Major
Other interactions of Ribociclib
- Amiodarone + Ribociclib Contraindicated
- Cisapride + Ribociclib Contraindicated
- Dofetilide + Ribociclib Contraindicated
- Dronedarone + Ribociclib Contraindicated
- Flibanserin + Ribociclib Contraindicated
- Ibutilide + Ribociclib Contraindicated
Frequently asked questions
Can I take Ribociclib with Tamoxifen?
MediHelp rates the interaction as major. Ribociclib and Tamoxifen 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. Ribociclib increases tamoxifen exposure, and both drugs prolong the QT interval. The combination raises the risk of QT prolongation and arrhythmia, and its use is not recommended.
How serious is the interaction between Ribociclib and Tamoxifen?
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 the combination and use an alternative endocrine agent. If it cannot be avoided, monitor ECG and electrolytes closely.
What other medicines interact with Tamoxifen?
MediHelp also lists interactions of Tamoxifen with, for example, Amiodarone, Anastrozole, Bupropion. The full list is on the Tamoxifen page.
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