Drug interactions
Irinotecan + Ritonavir
Severity: Major
Irinotecan and Ritonavir: major interaction.
Last updated Sources: US FDA label
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 potently inhibits CYP3A4 and may increase irinotecan and SN-38 exposure. It also inhibits UGT1A1, which may raise SN-38 further, increasing diarrhea and neutropenia risk.
What this interaction means in plain words
Irinotecan 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.
Irinotecan belongs to Oncology; Ritonavir belongs to Anti Virals.
Why it happens
Ritonavir inhibits CYP3A4, P-glycoprotein and UGT1A1, reducing irinotecan and SN-38 clearance.
What to do
Avoid if possible and use an antiretroviral regimen without ritonavir. If it cannot be avoided, monitor blood counts and diarrhea closely and reduce the irinotecan dose.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Irinotecan and Ritonavir, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
References
Other interactions of Irinotecan
- Clozapine + Irinotecan Contraindicated
- Irinotecan + Sacituzumab govitecan Contraindicated
- Adenovirus types 4 and 7 live + Irinotecan Major
- Apalutamide + Irinotecan Major
- Atazanavir + Irinotecan Major
- Carbamazepine + Irinotecan Major
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 Irinotecan with Ritonavir?
MediHelp rates the interaction as major. Irinotecan 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 potently inhibits CYP3A4 and may increase irinotecan and SN-38 exposure. It also inhibits UGT1A1, which may raise SN-38 further, increasing diarrhea and neutropenia risk.
How serious is the interaction between Irinotecan 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 if possible and use an antiretroviral regimen without ritonavir. If it cannot be avoided, monitor blood counts and diarrhea closely and reduce the irinotecan dose.
What other medicines interact with Irinotecan?
MediHelp also lists interactions of Irinotecan with, for example, Clozapine, Sacituzumab govitecan, Adenovirus types 4 and 7 live. The full list is on the Irinotecan page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
