Drug interactions
Phenobarbital + Tolterodine
Severity: Minor
Phenobarbital and Tolterodine: 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
Phenobarbital is an inducer of CYP3A4 and other enzymes, and may lower tolterodine concentrations. The effect is generally modest for most patients but may matter in CYP2D6 poor metabolizers who rely on CYP3A4.
What this interaction means in plain words
Phenobarbital and Tolterodine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Enzyme induction by phenobarbital accelerates tolterodine metabolism.
What to do
Monitor for reduced efficacy and adjust tolterodine dose if symptoms are not controlled.
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 Tolterodine
Frequently asked questions
Can I take Phenobarbital with Tolterodine?
MediHelp rates the interaction as minor. Phenobarbital and Tolterodine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenobarbital is an inducer of CYP3A4 and other enzymes, and may lower tolterodine concentrations. The effect is generally modest for most patients but may matter in CYP2D6 poor metabolizers who rely on CYP3A4.
How serious is the interaction between Phenobarbital and Tolterodine?
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 reduced efficacy and adjust tolterodine dose if symptoms are not controlled.
What other medicines interact with Tolterodine?
MediHelp also lists interactions of Tolterodine with, for example, Clarithromycin, Clozapine, Cobicistat. The full list is on the Tolterodine page.
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