Drug interactions
Fostamatinib + Ketoconazole
Severity: Moderate
Fostamatinib and Ketoconazole: 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
Ketoconazole raises exposure to R406, the active metabolite of fostamatinib. This may increase dose-related toxicities such as hypertension, diarrhea, hepatotoxicity and neutropenia.
What this interaction means in plain words
Fostamatinib and Ketoconazole 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.
Fostamatinib belongs to Oncology; Ketoconazole belongs to Anti Fungals.
Why it happens
Strong CYP3A4 inhibition reduces R406 metabolism.
What to do
Monitor blood pressure, liver tests and blood counts, and reduce the fostamatinib dose if toxicity develops.
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 Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Other interactions of Fostamatinib
- Colchicine + Fostamatinib Major
- Fostamatinib + Phenytoin Major
- Amobarbital + Fostamatinib Moderate
- Apalutamide + Fostamatinib Moderate
- Atorvastatin + Fostamatinib Moderate
- Bosentan + Fostamatinib Moderate
Frequently asked questions
Can I take Fostamatinib with Ketoconazole?
MediHelp rates the interaction as moderate. Fostamatinib and Ketoconazole 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. Ketoconazole raises exposure to R406, the active metabolite of fostamatinib. This may increase dose-related toxicities such as hypertension, diarrhea, hepatotoxicity and neutropenia.
How serious is the interaction between Fostamatinib and Ketoconazole?
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 blood pressure, liver tests and blood counts, and reduce the fostamatinib dose if toxicity develops.
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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