Drug interactions
Ketoconazole + Letermovir
Severity: Moderate
Ketoconazole and Letermovir: 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
Letermovir inhibits CYP3A and may modestly increase ketoconazole exposure, while ketoconazole may raise letermovir levels. Overall the effect on letermovir is small and typically tolerated.
What this interaction means in plain words
Ketoconazole and Letermovir 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.
Ketoconazole belongs to Anti Fungals; Letermovir belongs to Anti Virals.
Why it happens
Letermovir inhibits CYP3A4, and ketoconazole may modestly inhibit letermovir elimination pathways including OATP1B1/3.
What to do
No empirical dose change is required; monitor for ketoconazole-related adverse effects including hepatotoxicity and for letermovir adverse effects such as gastrointestinal symptoms.
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 Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Other interactions of Letermovir
- Ergotamine + Letermovir Contraindicated
- Letermovir + Pimozide Contraindicated
- Apalutamide + Letermovir Major
- Atorvastatin + Letermovir Major
- Carbamazepine + Letermovir Major
- Colchicine + Letermovir Major
Frequently asked questions
Can I take Ketoconazole with Letermovir?
MediHelp rates the interaction as moderate. Ketoconazole and Letermovir 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. Letermovir inhibits CYP3A and may modestly increase ketoconazole exposure, while ketoconazole may raise letermovir levels. Overall the effect on letermovir is small and typically tolerated.
How serious is the interaction between Ketoconazole and Letermovir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No empirical dose change is required; monitor for ketoconazole-related adverse effects including hepatotoxicity and for letermovir adverse effects such as gastrointestinal symptoms.
What other medicines interact with Ketoconazole?
MediHelp also lists interactions of Ketoconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Ketoconazole page.
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