Drug interactions
Darifenacin + Lonafarnib
Severity: Major
Darifenacin and Lonafarnib: major interaction.
Last updated Sources: US FDA label
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
Lonafarnib is a strong CYP3A4 inhibitor and could raise darifenacin exposure. Darifenacin is a weak CYP3A4 inhibitor and could modestly raise lonafarnib levels.
What this interaction means in plain words
Darifenacin and Lonafarnib 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; Lonafarnib belongs to Miscellaneous.
Why it happens
Bidirectional CYP3A4 interaction, with lonafarnib the dominant strong inhibitor.
What to do
Avoid the combination where possible. If unavoidable, limit darifenacin to 7.5 mg daily and monitor for anticholinergic effects, and for palpitations or syncope given lonafarnib's uncertain effect on QT.
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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References
Other interactions of Darifenacin
Other interactions of Lonafarnib
- Alfuzosin + Lonafarnib Contraindicated
- Amobarbital + Lonafarnib Contraindicated
- Apalutamide + Lonafarnib Contraindicated
- Bosentan + Lonafarnib Contraindicated
- Carbamazepine + Lonafarnib Contraindicated
- Clarithromycin + Lonafarnib Contraindicated
Frequently asked questions
Can I take Darifenacin with Lonafarnib?
MediHelp rates the interaction as major. Darifenacin and Lonafarnib 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. Lonafarnib is a strong CYP3A4 inhibitor and could raise darifenacin exposure. Darifenacin is a weak CYP3A4 inhibitor and could modestly raise lonafarnib levels.
How serious is the interaction between Darifenacin and Lonafarnib?
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. If unavoidable, limit darifenacin to 7.5 mg daily and monitor for anticholinergic effects, and for palpitations or syncope given lonafarnib's uncertain effect on QT.
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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