Drug interactions
Darifenacin + Zafirlukast
Severity: Minor
Darifenacin and Zafirlukast: 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
Darifenacin is metabolized by CYP3A4 and CYP2D6, so CYP3A4 inhibitors can raise its levels and anticholinergic effects. Zafirlukast is a weak inhibitor, so the effect is likely small.
What this interaction means in plain words
Darifenacin and Zafirlukast have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Darifenacin belongs to Genitourinary; Zafirlukast belongs to Respiratory.
Why it happens
Weak CYP3A4 inhibition by zafirlukast may reduce darifenacin metabolism.
What to do
Monitor for dry mouth, constipation and urinary retention. Keep darifenacin at the lowest effective dose if these appear.
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 Zafirlukast
- Pimozide + Zafirlukast Contraindicated
- Lomitapide + Zafirlukast Major
- Nilotinib + Zafirlukast Major
- Warfarin + Zafirlukast Major
- Apalutamide + Zafirlukast Moderate
- Carbamazepine + Zafirlukast Moderate
Other interactions of Darifenacin
Frequently asked questions
Can I take Darifenacin with Zafirlukast?
MediHelp rates the interaction as minor. Darifenacin and Zafirlukast have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Darifenacin is metabolized by CYP3A4 and CYP2D6, so CYP3A4 inhibitors can raise its levels and anticholinergic effects. Zafirlukast is a weak inhibitor, so the effect is likely small.
How serious is the interaction between Darifenacin and Zafirlukast?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for dry mouth, constipation and urinary retention. Keep darifenacin at the lowest effective dose if these appear.
What other medicines interact with Zafirlukast?
MediHelp also lists interactions of Zafirlukast with, for example, Pimozide, Lomitapide, Nilotinib. The full list is on the Zafirlukast page.
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