Drug interactions
Itraconazole + Tolterodine
Severity: Major
Itraconazole and Tolterodine: major interaction.
Last updated Sources: US FDA label
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
Itraconazole is a strong CYP3A4 inhibitor and increases tolterodine exposure, which is most relevant in CYP2D6 poor metabolizers. Higher levels raise the risk of anticholinergic effects and QT prolongation.
What this interaction means in plain words
Itraconazole and Tolterodine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Itraconazole belongs to Anti Fungals; Tolterodine belongs to Genitourinary.
Why it happens
Strong CYP3A4 inhibition by itraconazole reduces tolterodine clearance.
What to do
Do not exceed tolterodine 2 mg daily while on itraconazole, and monitor for anticholinergic toxicity and QT prolongation.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Tolterodine
Other interactions of Itraconazole
- Alfuzosin + Itraconazole Contraindicated
- Alprazolam + Itraconazole Contraindicated
- Avanafil + Itraconazole Contraindicated
- Conivaptan + Itraconazole Contraindicated
- Dihydroergotamine intranasal + Itraconazole Contraindicated
- Dihydroergotamine + Itraconazole Contraindicated
Frequently asked questions
Can I take Itraconazole with Tolterodine?
MediHelp rates the interaction as major. Itraconazole and Tolterodine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Itraconazole is a strong CYP3A4 inhibitor and increases tolterodine exposure, which is most relevant in CYP2D6 poor metabolizers. Higher levels raise the risk of anticholinergic effects and QT prolongation.
How serious is the interaction between Itraconazole and Tolterodine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Do not exceed tolterodine 2 mg daily while on itraconazole, and monitor for anticholinergic toxicity and QT prolongation.
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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