Drug interactions
Isoniazid + Tolterodine
Severity: Minor
Isoniazid 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
Isoniazid is a weak inhibitor of CYP3A4 and other CYP enzymes, so it could slightly increase tolterodine exposure. Clinical significance is likely small, since most patients clear tolterodine mainly via CYP2D6.
What this interaction means in plain words
Isoniazid 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.
Isoniazid belongs to Anti Bacterial; Tolterodine belongs to Genitourinary.
Why it happens
Weak inhibition of CYP3A4-mediated tolterodine metabolism.
What to do
No dose change is required. Be aware of increased anticholinergic effects in poor CYP2D6 metabolisers.
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
Other interactions of Isoniazid
Frequently asked questions
Can I take Isoniazid with Tolterodine?
MediHelp rates the interaction as minor. Isoniazid 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. Isoniazid is a weak inhibitor of CYP3A4 and other CYP enzymes, so it could slightly increase tolterodine exposure. Clinical significance is likely small, since most patients clear tolterodine mainly via CYP2D6.
How serious is the interaction between Isoniazid 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: No dose change is required. Be aware of increased anticholinergic effects in poor CYP2D6 metabolisers.
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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