Drug interactions
Irinotecan + Ketoconazole
Severity: Major
Irinotecan and Ketoconazole: 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
Ketoconazole raises exposure to irinotecan and its active metabolite SN-38, which can worsen severe diarrhea and neutropenia. Irinotecan labeling advises against strong CYP3A4 inhibitors.
What this interaction means in plain words
Irinotecan and Ketoconazole 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; Ketoconazole belongs to Anti Fungals.
Why it happens
CYP3A4 inhibition reduces conversion of irinotecan to inactive metabolites, and ketoconazole may also inhibit UGT1A1 glucuronidation of SN-38.
What to do
Stop strong CYP3A4 inhibitors at least one week before starting irinotecan, or use a non-inhibiting antifungal. If unavoidable, monitor closely for diarrhea and neutropenia.
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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References
Other interactions of Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
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
Frequently asked questions
Can I take Irinotecan with Ketoconazole?
MediHelp rates the interaction as major. Irinotecan and Ketoconazole 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. Ketoconazole raises exposure to irinotecan and its active metabolite SN-38, which can worsen severe diarrhea and neutropenia. Irinotecan labeling advises against strong CYP3A4 inhibitors.
How serious is the interaction between Irinotecan and Ketoconazole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Stop strong CYP3A4 inhibitors at least one week before starting irinotecan, or use a non-inhibiting antifungal. If unavoidable, monitor closely for diarrhea and neutropenia.
What other medicines interact with Ketoconazole?
MediHelp also lists interactions of Ketoconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Ketoconazole page.
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