Drug interactions
Darifenacin + Erythromycin stearate
Severity: Moderate
Darifenacin and Erythromycin stearate: 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
Erythromycin is a moderate CYP3A4 inhibitor and raises darifenacin exposure, increasing anticholinergic effects. Erythromycin also prolongs QT.
What this interaction means in plain words
Darifenacin and Erythromycin stearate 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.
Why it happens
Erythromycin inhibits CYP3A4 metabolism of darifenacin.
What to do
Limit darifenacin to 7.5 mg daily during erythromycin therapy and monitor for anticholinergic effects. Consider an alternative antibiotic such as azithromycin if QT risk is a concern.
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
Frequently asked questions
Can I take Darifenacin with Erythromycin stearate?
MediHelp rates the interaction as moderate. Darifenacin and Erythromycin stearate 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. Erythromycin is a moderate CYP3A4 inhibitor and raises darifenacin exposure, increasing anticholinergic effects. Erythromycin also prolongs QT.
How serious is the interaction between Darifenacin and Erythromycin stearate?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Limit darifenacin to 7.5 mg daily during erythromycin therapy and monitor for anticholinergic effects. Consider an alternative antibiotic such as azithromycin if QT risk is a concern.
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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