Drug interactions
Fesoterodine + Ketoconazole
Severity: Moderate
Fesoterodine 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 is a strong CYP3A4 inhibitor and raises exposure to the active metabolite of fesoterodine. This increases the likelihood of anticholinergic adverse effects.
What this interaction means in plain words
Fesoterodine 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.
Fesoterodine belongs to Genitourinary; Ketoconazole belongs to Anti Fungals.
Why it happens
Strong CYP3A4 inhibition reduces clearance of the active metabolite of fesoterodine.
What to do
Do not exceed fesoterodine 4 mg daily with ketoconazole and monitor for dry mouth, constipation and urinary retention.
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 Fesoterodine
Other interactions of Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Frequently asked questions
Can I take Fesoterodine with Ketoconazole?
MediHelp rates the interaction as moderate. Fesoterodine 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 is a strong CYP3A4 inhibitor and raises exposure to the active metabolite of fesoterodine. This increases the likelihood of anticholinergic adverse effects.
How serious is the interaction between Fesoterodine 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: Do not exceed fesoterodine 4 mg daily with ketoconazole and monitor for dry mouth, constipation and urinary retention.
What other medicines interact with Fesoterodine?
MediHelp also lists interactions of Fesoterodine with, for example, Bethanechol, Clozapine, Levoketoconazole. The full list is on the Fesoterodine page.
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