Drug interactions
Clozapine + Darifenacin
Severity: Major
Clozapine and Darifenacin: 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
Both drugs have anticholinergic activity, and clozapine already causes constipation that can progress to severe gastrointestinal hypomotility or ileus. Adding darifenacin raises the risk of constipation, urinary retention, tachycardia and cognitive effects. Darifenacin may also modestly increase clozapine exposure by CYP2D6 inhibition.
What this interaction means in plain words
Clozapine and Darifenacin 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.
Clozapine belongs to Central Nervous System; Darifenacin belongs to Genitourinary.
Why it happens
Additive antimuscarinic effects, with possible CYP2D6 inhibition by darifenacin raising clozapine levels.
What to do
Avoid the combination where possible, or monitor bowel function closely and treat constipation early. Review the need for darifenacin and reduce the clozapine dose if toxicity occurs.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Clozapine and Darifenacin, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Darifenacin
Other interactions of Clozapine
- Clozapine + Deferiprone Contraindicated
- Clozapine + Irinotecan Contraindicated
- Clozapine + Pimozide Contraindicated
- Clozapine + Thioridazine Contraindicated
- Acalabrutinib + Clozapine Major
- Adagrasib + Clozapine Major
Frequently asked questions
Can I take Clozapine with Darifenacin?
MediHelp rates the interaction as major. Clozapine and Darifenacin 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. Both drugs have anticholinergic activity, and clozapine already causes constipation that can progress to severe gastrointestinal hypomotility or ileus. Adding darifenacin raises the risk of constipation, urinary retention, tachycardia and cognitive effects. Darifenacin may also modestly increase clozapine exposure by CYP2D6 inhibition.
How serious is the interaction between Clozapine and Darifenacin?
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, or monitor bowel function closely and treat constipation early. Review the need for darifenacin and reduce the clozapine dose if toxicity occurs.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
