Drug interactions
Itraconazole + Toremifene
Severity: Major
Itraconazole and Toremifene: 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
Toremifene prolongs the QT interval in a dose-related fashion, and itraconazole can add to this. Itraconazole also inhibits CYP3A4, which raises toremifene levels, further increasing the risk of torsades de pointes.
What this interaction means in plain words
Itraconazole and Toremifene 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; Toremifene belongs to Endocrine.
Why it happens
Additive QTc prolongation plus CYP3A4 inhibition of toremifene metabolism.
What to do
Avoid the combination where possible. If a strong CYP3A4 inhibitor is required, obtain ECG monitoring, correct electrolytes, and consider toremifene dose reduction or interruption.
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 Itraconazole
- Alfuzosin + Itraconazole Contraindicated
- Alprazolam + Itraconazole Contraindicated
- Avanafil + Itraconazole Contraindicated
- Conivaptan + Itraconazole Contraindicated
- Dihydroergotamine intranasal + Itraconazole Contraindicated
- Dihydroergotamine + Itraconazole Contraindicated
Other interactions of Toremifene
- Amiodarone + Toremifene Contraindicated
- Dronedarone + Toremifene Contraindicated
- Nilotinib + Toremifene Contraindicated
- Pimozide + Toremifene Contraindicated
- Quinidine + Toremifene Contraindicated
- Ribociclib + Toremifene Contraindicated
Frequently asked questions
Can I take Itraconazole with Toremifene?
MediHelp rates the interaction as major. Itraconazole and Toremifene 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. Toremifene prolongs the QT interval in a dose-related fashion, and itraconazole can add to this. Itraconazole also inhibits CYP3A4, which raises toremifene levels, further increasing the risk of torsades de pointes.
How serious is the interaction between Itraconazole and Toremifene?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where possible. If a strong CYP3A4 inhibitor is required, obtain ECG monitoring, correct electrolytes, and consider toremifene dose reduction or interruption.
What other medicines interact with Itraconazole?
MediHelp also lists interactions of Itraconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Itraconazole page.
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