Drug interactions
Istradefylline + Solifenacin
Severity: Minor
Istradefylline and Solifenacin: minor 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
At 40 mg daily istradefylline weakly inhibits CYP3A4 and may modestly raise levels of sensitive substrates such as solifenacin. The effect was not seen at 20 mg daily, so risk depends on the dose.
What this interaction means in plain words
Istradefylline and Solifenacin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Istradefylline belongs to Central Nervous System; Solifenacin belongs to Genitourinary.
Why it happens
Weak CYP3A4 inhibition by istradefylline at higher doses reduces solifenacin metabolism.
What to do
No adjustment is usually needed at the 20 mg istradefylline dose; with 40 mg, monitor for anticholinergic effects and consider reducing the solifenacin dose.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Solifenacin
Other interactions of Istradefylline
Frequently asked questions
Can I take Istradefylline with Solifenacin?
MediHelp rates the interaction as minor. Istradefylline and Solifenacin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. At 40 mg daily istradefylline weakly inhibits CYP3A4 and may modestly raise levels of sensitive substrates such as solifenacin. The effect was not seen at 20 mg daily, so risk depends on the dose.
How serious is the interaction between Istradefylline and Solifenacin?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No adjustment is usually needed at the 20 mg istradefylline dose; with 40 mg, monitor for anticholinergic effects and consider reducing the solifenacin dose.
What other medicines interact with Solifenacin?
MediHelp also lists interactions of Solifenacin with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Solifenacin page.
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