Drug interactions
Oxybutynin + Physostigmine
Severity: Moderate
Oxybutynin and Physostigmine: 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
Physostigmine inhibits acetylcholinesterase and increases cholinergic activity, which opposes the antimuscarinic action of oxybutynin. The result is reduced effect of one or both drugs, and this is the basis for physostigmine use in anticholinergic toxicity.
What this interaction means in plain words
Oxybutynin and Physostigmine 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
Pharmacodynamic antagonism between cholinesterase inhibition and muscarinic receptor blockade.
What to do
Avoid routine concurrent use; when physostigmine is given for oxybutynin toxicity, monitor heart rate, seizures and cholinergic effects.
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
Frequently asked questions
Can I take Oxybutynin with Physostigmine?
MediHelp rates the interaction as moderate. Oxybutynin and Physostigmine 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. Physostigmine inhibits acetylcholinesterase and increases cholinergic activity, which opposes the antimuscarinic action of oxybutynin. The result is reduced effect of one or both drugs, and this is the basis for physostigmine use in anticholinergic toxicity.
How serious is the interaction between Oxybutynin and Physostigmine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid routine concurrent use; when physostigmine is given for oxybutynin toxicity, monitor heart rate, seizures and cholinergic effects.
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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