Drug interactions
Posaconazole + Tolterodine
Severity: Major
Posaconazole 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
Posaconazole is a strong CYP3A4 inhibitor and raises tolterodine exposure, particularly in CYP2D6 poor metabolizers. Both drugs can prolong the QT interval, so the risk of QT-related arrhythmia is increased.
What this interaction means in plain words
Posaconazole 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.
Posaconazole belongs to Anti Fungals; Tolterodine belongs to Genitourinary.
Why it happens
Strong CYP3A4 inhibition reduces tolterodine clearance, with additive QT prolongation.
What to do
Limit tolterodine to the lower labeled dose during the combination and monitor the ECG and electrolytes. Consider an alternative antimuscarinic if QTc risk is high.
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 Posaconazole
- Artemether + Posaconazole Contraindicated
- Avanafil + Posaconazole Contraindicated
- Cobimetinib + Posaconazole Contraindicated
- Conivaptan + Posaconazole Contraindicated
- Dihydroergotamine intranasal + Posaconazole Contraindicated
- Dihydroergotamine + Posaconazole Contraindicated
Frequently asked questions
Can I take Posaconazole with Tolterodine?
MediHelp rates the interaction as major. Posaconazole 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. Posaconazole is a strong CYP3A4 inhibitor and raises tolterodine exposure, particularly in CYP2D6 poor metabolizers. Both drugs can prolong the QT interval, so the risk of QT-related arrhythmia is increased.
How serious is the interaction between Posaconazole 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: Limit tolterodine to the lower labeled dose during the combination and monitor the ECG and electrolytes. Consider an alternative antimuscarinic if QTc risk is high.
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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