Drug interactions
Fluconazole + Fostemsavir
Severity: Moderate
Fluconazole and Fostemsavir: moderate interaction.
Last updated
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 have QT-prolonging potential. Fostemsavir's active metabolite temsavir has been associated with QTc prolongation at supratherapeutic exposures, and fluconazole can additionally contribute to QT effects. Fluconazole may also modestly raise temsavir exposure through CYP3A4 inhibition.
What this interaction means in plain words
Fluconazole and Fostemsavir can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Fluconazole belongs to Anti Fungals; Fostemsavir belongs to Anti Virals.
Why it happens
Additive QTc prolongation, with possible increased temsavir exposure due to CYP3A4 inhibition by fluconazole.
What to do
Obtain a baseline ECG and correct hypokalemia and hypomagnesemia. Monitor the ECG in patients with additional QT risk factors or other QT-prolonging drugs.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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 Fostemsavir
- Apalutamide + Fostemsavir Contraindicated
- Carbamazepine + Fostemsavir Contraindicated
- Enzalutamide + Fostemsavir Contraindicated
- Fostemsavir + Mitotane Contraindicated
- Fostemsavir + Phenytoin Contraindicated
- Fostemsavir + Rifampicin Contraindicated
Frequently asked questions
Can I take Fluconazole with Fostemsavir?
MediHelp rates the interaction as moderate. Fluconazole and Fostemsavir can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Both drugs have QT-prolonging potential. Fostemsavir's active metabolite temsavir has been associated with QTc prolongation at supratherapeutic exposures, and fluconazole can additionally contribute to QT effects. Fluconazole may also modestly raise temsavir exposure through CYP3A4 inhibition.
How serious is the interaction between Fluconazole and Fostemsavir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Obtain a baseline ECG and correct hypokalemia and hypomagnesemia. Monitor the ECG in patients with additional QT risk factors or other QT-prolonging drugs.
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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