Drug interactions
Darifenacin + Idelalisib
Severity: Major
Darifenacin and Idelalisib: major 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
Idelalisib is a strong CYP3A4 inhibitor and can substantially increase darifenacin exposure, raising anticholinergic toxicity and QT concerns.
What this interaction means in plain words
Darifenacin and Idelalisib can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Darifenacin belongs to Genitourinary; Idelalisib belongs to Oncology.
Why it happens
Idelalisib strongly inhibits CYP3A4 metabolism of darifenacin.
What to do
Avoid the combination where possible and choose a bladder agent not reliant on CYP3A4. If used, keep darifenacin at 7.5 mg daily at most and monitor for anticholinergic toxicity.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Darifenacin
Other interactions of Idelalisib
- Alfuzosin + Idelalisib Contraindicated
- Cisapride + Idelalisib Contraindicated
- Dihydroergotamine + Idelalisib Contraindicated
- Dronedarone + Idelalisib Contraindicated
- Eletriptan + Idelalisib Contraindicated
- Eplerenone + Idelalisib Contraindicated
Frequently asked questions
Can I take Darifenacin with Idelalisib?
MediHelp rates the interaction as major. Darifenacin and Idelalisib can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Idelalisib is a strong CYP3A4 inhibitor and can substantially increase darifenacin exposure, raising anticholinergic toxicity and QT concerns.
How serious is the interaction between Darifenacin and Idelalisib?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where possible and choose a bladder agent not reliant on CYP3A4. If used, keep darifenacin at 7.5 mg daily at most and monitor for anticholinergic toxicity.
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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