Drug interactions
Fosamprenavir + Ribociclib
Severity: Major
Fosamprenavir and Ribociclib: 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
Fosamprenavir, converted to amprenavir and often boosted with ritonavir, inhibits CYP3A4 and raises ribociclib exposure. This increases the risk of QT prolongation and neutropenia.
What this interaction means in plain words
Fosamprenavir and Ribociclib 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.
Why it happens
Inhibition of CYP3A4 by amprenavir reduces ribociclib clearance.
What to do
Avoid if possible; otherwise reduce the ribociclib starting dose to 400 mg daily and monitor ECG and blood counts.
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 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 Fosamprenavir with Ribociclib?
MediHelp rates the interaction as major. Fosamprenavir and Ribociclib 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. Fosamprenavir, converted to amprenavir and often boosted with ritonavir, inhibits CYP3A4 and raises ribociclib exposure. This increases the risk of QT prolongation and neutropenia.
How serious is the interaction between Fosamprenavir and Ribociclib?
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; otherwise reduce the ribociclib starting dose to 400 mg daily and monitor ECG and blood counts.
What other medicines interact with Ribociclib?
MediHelp also lists interactions of Ribociclib with, for example, Amiodarone, Cisapride, Dofetilide. The full list is on the Ribociclib page.
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