Drug interactions
Fosamprenavir + Palbociclib
Severity: Major
Fosamprenavir and Palbociclib: 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 may raise palbociclib exposure. This increases the risk of neutropenia.
What this interaction means in plain words
Fosamprenavir and Palbociclib 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 reduces palbociclib metabolic clearance.
What to do
Avoid if possible. If unavoidable, reduce palbociclib to 75 mg daily and monitor 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 Palbociclib
Frequently asked questions
Can I take Fosamprenavir with Palbociclib?
MediHelp rates the interaction as major. Fosamprenavir and Palbociclib 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 may raise palbociclib exposure. This increases the risk of neutropenia.
How serious is the interaction between Fosamprenavir and Palbociclib?
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. If unavoidable, reduce palbociclib to 75 mg daily and monitor blood counts.
What other medicines interact with Palbociclib?
MediHelp also lists interactions of Palbociclib with, for example, Apalutamide, Atazanavir, Carbamazepine. The full list is on the Palbociclib page.
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