Drug interactions
Fosaprepitant + Ritonavir
Severity: Moderate
Fosaprepitant and Ritonavir: 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
Fosaprepitant is converted to aprepitant, whose levels rise with strong CYP3A4 inhibitors like ritonavir. This may increase aprepitant adverse effects and alter other CYP3A4 substrates.
What this interaction means in plain words
Fosaprepitant and Ritonavir 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.
Fosaprepitant belongs to Gastrointestinal Tract; Ritonavir belongs to Anti Virals.
Why it happens
Ritonavir inhibits CYP3A4, reducing aprepitant clearance.
What to do
Monitor for aprepitant adverse effects such as fatigue and hypersensitivity; a single-dose fosaprepitant regimen is generally manageable.
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 Fosaprepitant
- Flibanserin + Fosaprepitant Contraindicated
- Fosaprepitant + Pimozide Contraindicated
- Alprazolam + Fosaprepitant Moderate
- Amiodarone + Fosaprepitant Moderate
- Amobarbital + Fosaprepitant Moderate
- Apalutamide + Fosaprepitant Moderate
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 Fosaprepitant with Ritonavir?
MediHelp rates the interaction as moderate. Fosaprepitant and Ritonavir 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. Fosaprepitant is converted to aprepitant, whose levels rise with strong CYP3A4 inhibitors like ritonavir. This may increase aprepitant adverse effects and alter other CYP3A4 substrates.
How serious is the interaction between Fosaprepitant and Ritonavir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for aprepitant adverse effects such as fatigue and hypersensitivity; a single-dose fosaprepitant regimen is generally manageable.
What other medicines interact with Fosaprepitant?
MediHelp also lists interactions of Fosaprepitant with, for example, Flibanserin, Pimozide, Alprazolam. The full list is on the Fosaprepitant page.
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