Drug interactions
Darifenacin + Phenytoin
Severity: Moderate
Darifenacin and Phenytoin: 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
Phenytoin induces CYP3A4 and may lower darifenacin exposure, reducing its effect on bladder symptoms.
What this interaction means in plain words
Darifenacin and Phenytoin 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.
Darifenacin belongs to Genitourinary; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4, increasing the metabolism of darifenacin.
What to do
Monitor symptom control and titrate darifenacin within the labeled range. Consider an alternative agent if the response is inadequate.
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 Darifenacin
Other interactions of Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Darifenacin with Phenytoin?
MediHelp rates the interaction as moderate. Darifenacin and Phenytoin 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. Phenytoin induces CYP3A4 and may lower darifenacin exposure, reducing its effect on bladder symptoms.
How serious is the interaction between Darifenacin and Phenytoin?
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 symptom control and titrate darifenacin within the labeled range. Consider an alternative agent if the response is inadequate.
What other medicines interact with Darifenacin?
MediHelp also lists interactions of Darifenacin with, for example, Atazanavir, Bethanechol, Clarithromycin. The full list is on the Darifenacin page.
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