Drug interactions
Darunavir + Oxybutynin
Severity: Moderate
Darunavir and Oxybutynin: 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
Darunavir, usually boosted with ritonavir or cobicistat, inhibits CYP3A4 and may raise oxybutynin levels. This may increase anticholinergic effects such as dry mouth, constipation, confusion and urinary retention.
What this interaction means in plain words
Darunavir and Oxybutynin 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.
Darunavir belongs to Anti Virals; Oxybutynin belongs to Genitourinary.
Why it happens
Inhibition of CYP3A4 reduces first-pass and systemic metabolism of oxybutynin.
What to do
Start oxybutynin at a low dose and monitor for anticholinergic toxicity, reducing the dose if needed.
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 Oxybutynin
Other interactions of Darunavir
- Alfuzosin + Darunavir Contraindicated
- Avanafil + Darunavir Contraindicated
- Darunavir + Dronedarone Contraindicated
- Darunavir + Eletriptan Contraindicated
- Darunavir + Ergotamine Contraindicated
- Darunavir + Flibanserin Contraindicated
Frequently asked questions
Can I take Darunavir with Oxybutynin?
MediHelp rates the interaction as moderate. Darunavir and Oxybutynin 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. Darunavir, usually boosted with ritonavir or cobicistat, inhibits CYP3A4 and may raise oxybutynin levels. This may increase anticholinergic effects such as dry mouth, constipation, confusion and urinary retention.
How serious is the interaction between Darunavir and Oxybutynin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Start oxybutynin at a low dose and monitor for anticholinergic toxicity, reducing the dose if needed.
What other medicines interact with Oxybutynin?
MediHelp also lists interactions of Oxybutynin with, for example, Bethanechol, Clozapine, Potassium chloride. The full list is on the Oxybutynin page.
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