Drug interactions
Fluconazole + Selpercatinib
Severity: Major
Fluconazole and Selpercatinib: major interaction.
Last updated Sources: Health Canada product monograph
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
Both drugs can prolong the QT interval, so combining them may increase the risk of torsades de pointes. Fluconazole may also raise selpercatinib exposure.
What this interaction means in plain words
Fluconazole and Selpercatinib 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.
Fluconazole belongs to Anti Fungals; Selpercatinib belongs to Oncology.
Why it happens
Additive QT prolongation, plus fluconazole CYP3A4 inhibition may increase selpercatinib levels.
What to do
Avoid the combination if possible, otherwise monitor ECG and electrolytes. Consider reducing the selpercatinib dose when used with a moderate CYP3A4 inhibitor, per labeling.
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 Fluconazole
- Dihydroergotamine intranasal + Fluconazole Contraindicated
- Dihydroergotamine + Fluconazole Contraindicated
- Dofetilide + Fluconazole Contraindicated
- Domperidone + Fluconazole Contraindicated
- Dronedarone + Fluconazole Contraindicated
- Erythromycin + Fluconazole Contraindicated
Other interactions of Selpercatinib
Frequently asked questions
Can I take Fluconazole with Selpercatinib?
MediHelp rates the interaction as major. Fluconazole and Selpercatinib 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. Both drugs can prolong the QT interval, so combining them may increase the risk of torsades de pointes. Fluconazole may also raise selpercatinib exposure.
How serious is the interaction between Fluconazole and Selpercatinib?
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 if possible, otherwise monitor ECG and electrolytes. Consider reducing the selpercatinib dose when used with a moderate CYP3A4 inhibitor, per labeling.
What other medicines interact with Fluconazole?
MediHelp also lists interactions of Fluconazole with, for example, Dihydroergotamine intranasal, Dihydroergotamine, Dofetilide. The full list is on the Fluconazole page.
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