Drug interactions
Posaconazole + Toremifene
Severity: Major
Posaconazole and Toremifene: major interaction.
Last updated Sources: EMA SmPC
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 may raise toremifene concentrations, and both drugs can prolong the QT interval. This increases the risk of serious ventricular arrhythmias including torsades de pointes.
What this interaction means in plain words
Posaconazole 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.
Posaconazole belongs to Anti Fungals; Toremifene belongs to Endocrine.
Why it happens
CYP3A4 inhibition reduces toremifene clearance, combined with additive QT-prolonging pharmacodynamic effects.
What to do
Avoid the combination when possible. If it cannot be avoided, monitor ECG and correct potassium and magnesium disturbances.
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 Posaconazole
- Artemether + Posaconazole Contraindicated
- Avanafil + Posaconazole Contraindicated
- Cobimetinib + Posaconazole Contraindicated
- Conivaptan + Posaconazole Contraindicated
- Dihydroergotamine intranasal + Posaconazole Contraindicated
- Dihydroergotamine + Posaconazole 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 Posaconazole with Toremifene?
MediHelp rates the interaction as major. Posaconazole 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. Posaconazole may raise toremifene concentrations, and both drugs can prolong the QT interval. This increases the risk of serious ventricular arrhythmias including torsades de pointes.
How serious is the interaction between Posaconazole 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 when possible. If it cannot be avoided, monitor ECG and correct potassium and magnesium disturbances.
What other medicines interact with Posaconazole?
MediHelp also lists interactions of Posaconazole with, for example, Artemether, Avanafil, Cobimetinib. The full list is on the Posaconazole page.
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