Drug interactions
Nelfinavir + Oxybutynin
Severity: Moderate
Nelfinavir 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
Nelfinavir inhibits CYP3A4 and may increase oxybutynin concentrations, raising the risk of anticholinergic adverse effects such as dry mouth, constipation, confusion and urinary retention. The effect is most relevant with immediate-release oxybutynin in older or frail patients.
What this interaction means in plain words
Nelfinavir 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.
Nelfinavir belongs to Anti Virals; Oxybutynin belongs to Genitourinary.
Why it happens
Inhibition of CYP3A4-mediated oxybutynin metabolism in the gut wall and liver by nelfinavir.
What to do
Monitor for anticholinergic toxicity and consider starting oxybutynin at a lower dose, titrating to response.
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 Nelfinavir
- Alfuzosin + Nelfinavir Contraindicated
- Avanafil + Nelfinavir Contraindicated
- Dronedarone + Nelfinavir Contraindicated
- Eletriptan + Nelfinavir Contraindicated
- Ergotamine + Nelfinavir Contraindicated
- Flibanserin + Nelfinavir Contraindicated
Frequently asked questions
Can I take Nelfinavir with Oxybutynin?
MediHelp rates the interaction as moderate. Nelfinavir 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. Nelfinavir inhibits CYP3A4 and may increase oxybutynin concentrations, raising the risk of anticholinergic adverse effects such as dry mouth, constipation, confusion and urinary retention. The effect is most relevant with immediate-release oxybutynin in older or frail patients.
How serious is the interaction between Nelfinavir 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: Monitor for anticholinergic toxicity and consider starting oxybutynin at a lower dose, titrating to response.
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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