Drug interactions
Darifenacin + Diltiazem
Severity: Moderate
Darifenacin and Diltiazem: 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
Diltiazem is a moderate CYP3A4 inhibitor and darifenacin is cleared mainly by CYP3A4. Darifenacin exposure may increase, which raises anticholinergic adverse effects such as dry mouth and constipation.
What this interaction means in plain words
Darifenacin and Diltiazem 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; Diltiazem belongs to Cardiovascular.
Why it happens
Diltiazem inhibits CYP3A4, reducing darifenacin metabolism.
What to do
Monitor for anticholinergic effects. Keep the darifenacin dose at 7.5 mg daily if a moderate CYP3A4 inhibitor is used and tolerability is poor.
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 Diltiazem
- Diltiazem + Flibanserin Contraindicated
- Diltiazem + Ivabradine Contraindicated
- Diltiazem + Lomitapide Contraindicated
- Diltiazem + Lonafarnib Contraindicated
- Acebutolol + Diltiazem Major
- Alfentanil + Diltiazem Major
Frequently asked questions
Can I take Darifenacin with Diltiazem?
MediHelp rates the interaction as moderate. Darifenacin and Diltiazem 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. Diltiazem is a moderate CYP3A4 inhibitor and darifenacin is cleared mainly by CYP3A4. Darifenacin exposure may increase, which raises anticholinergic adverse effects such as dry mouth and constipation.
How serious is the interaction between Darifenacin and Diltiazem?
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 effects. Keep the darifenacin dose at 7.5 mg daily if a moderate CYP3A4 inhibitor is used and tolerability is poor.
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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