Drug interactions
Fesoterodine + Ritonavir
Severity: Moderate
Fesoterodine 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
Ritonavir is a potent CYP3A4 inhibitor that increases exposure to the active metabolite of fesoterodine. This raises the risk of anticholinergic adverse effects such as dry mouth, constipation and urinary retention.
What this interaction means in plain words
Fesoterodine 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.
Fesoterodine belongs to Genitourinary; Ritonavir belongs to Anti Virals.
Why it happens
Potent CYP3A4 inhibition reduces clearance of the active fesoterodine metabolite.
What to do
Do not exceed fesoterodine 4 mg daily with ritonavir. Monitor for anticholinergic adverse effects.
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 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 Fesoterodine with Ritonavir?
MediHelp rates the interaction as moderate. Fesoterodine 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. Ritonavir is a potent CYP3A4 inhibitor that increases exposure to the active metabolite of fesoterodine. This raises the risk of anticholinergic adverse effects such as dry mouth, constipation and urinary retention.
How serious is the interaction between Fesoterodine 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: Do not exceed fesoterodine 4 mg daily with ritonavir. Monitor for anticholinergic adverse effects.
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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