Drug interactions
Darifenacin + Istradefylline
Severity: Moderate
Darifenacin and Istradefylline: 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
Istradefylline at higher doses inhibits CYP3A4 and can raise exposure to sensitive substrates such as darifenacin. This may increase antimuscarinic adverse effects.
What this interaction means in plain words
Darifenacin and Istradefylline 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; Istradefylline belongs to Central Nervous System.
Why it happens
Istradefylline inhibits CYP3A4, reducing darifenacin metabolism, mainly at the 40 mg/day dose.
What to do
Monitor for anticholinergic adverse effects and keep darifenacin at the lowest effective dose, particularly with istradefylline 40 mg/day.
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 Istradefylline
Frequently asked questions
Can I take Darifenacin with Istradefylline?
MediHelp rates the interaction as moderate. Darifenacin and Istradefylline 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. Istradefylline at higher doses inhibits CYP3A4 and can raise exposure to sensitive substrates such as darifenacin. This may increase antimuscarinic adverse effects.
How serious is the interaction between Darifenacin and Istradefylline?
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 for anticholinergic adverse effects and keep darifenacin at the lowest effective dose, particularly with istradefylline 40 mg/day.
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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