Drug interactions
Fostemsavir + Voriconazole
Severity: Moderate
Fostemsavir and Voriconazole: 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 agents can prolong the QT interval, and fostemsavir has caused QTc prolongation at supratherapeutic doses. Voriconazole may also raise the level of the fostemsavir active metabolite through CYP3A4 inhibition, increasing arrhythmia risk.
What this interaction means in plain words
Fostemsavir and Voriconazole 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.
Fostemsavir belongs to Anti Virals; Voriconazole belongs to Anti Fungals.
Why it happens
Additive QT prolongation with possible CYP3A4 inhibition raising temsavir exposure.
What to do
Obtain a baseline ECG and monitor QTc, and correct potassium and magnesium abnormalities, particularly in patients with other QT risk factors.
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 Voriconazole
- Avanafil + Voriconazole Contraindicated
- Butabarbital + Voriconazole Contraindicated
- Carbamazepine + Voriconazole Contraindicated
- Conivaptan + Voriconazole Contraindicated
- Dihydroergotamine intranasal + Voriconazole Contraindicated
- Dihydroergotamine + Voriconazole 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 Fostemsavir with Voriconazole?
MediHelp rates the interaction as moderate. Fostemsavir and Voriconazole 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 agents can prolong the QT interval, and fostemsavir has caused QTc prolongation at supratherapeutic doses. Voriconazole may also raise the level of the fostemsavir active metabolite through CYP3A4 inhibition, increasing arrhythmia risk.
How serious is the interaction between Fostemsavir and Voriconazole?
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 monitor QTc, and correct potassium and magnesium abnormalities, particularly in patients with other QT risk factors.
What other medicines interact with Voriconazole?
MediHelp also lists interactions of Voriconazole with, for example, Avanafil, Butabarbital, Carbamazepine. The full list is on the Voriconazole page.
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