Drug interactions
Palbociclib + Ritonavir
Severity: Major
Palbociclib and Ritonavir: 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
Ritonavir strongly inhibits CYP3A and raises palbociclib exposure. This increases the risk of neutropenia and other palbociclib toxicities.
What this interaction means in plain words
Palbociclib and Ritonavir 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.
Palbociclib belongs to Oncology; Ritonavir belongs to Anti Virals.
Why it happens
Ritonavir inhibits CYP3A4, reducing the metabolic clearance of palbociclib.
What to do
Avoid the combination where possible. If it cannot be avoided, reduce the palbociclib dose to 75 mg daily and monitor blood counts 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 Palbociclib
Other interactions of Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Palbociclib with Ritonavir?
MediHelp rates the interaction as major. Palbociclib and Ritonavir 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. Ritonavir strongly inhibits CYP3A and raises palbociclib exposure. This increases the risk of neutropenia and other palbociclib toxicities.
How serious is the interaction between Palbociclib and Ritonavir?
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 where possible. If it cannot be avoided, reduce the palbociclib dose to 75 mg daily and monitor blood counts closely.
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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