Drug interactions
Letermovir + Siponimod
Severity: Moderate
Letermovir and Siponimod: 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 induces CYP2C9/2C19, so the net effect on siponimod is unclear. It may raise exposure through CYP3A inhibition, which is more relevant in patients with reduced CYP2C9 function.
What this interaction means in plain words
Letermovir and Siponimod 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 belongs to Anti Virals; Siponimod belongs to Central Nervous System.
Why it happens
Moderate CYP3A inhibition by letermovir, partly offset by CYP2C9 induction, alters siponimod clearance.
What to do
Monitor heart rate and for adverse effects of siponimod. Avoid in patients with CYP2C9*3 variants where possible.
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 Siponimod
- Cladribine + Siponimod Contraindicated
- Fingolimod + Siponimod Contraindicated
- Fluconazole + Siponimod Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Siponimod Contraindicated
- Ponesimod + Siponimod Contraindicated
- Siponimod + Thioridazine 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 Letermovir with Siponimod?
MediHelp rates the interaction as moderate. Letermovir and Siponimod 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 induces CYP2C9/2C19, so the net effect on siponimod is unclear. It may raise exposure through CYP3A inhibition, which is more relevant in patients with reduced CYP2C9 function.
How serious is the interaction between Letermovir and Siponimod?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor heart rate and for adverse effects of siponimod. Avoid in patients with CYP2C9*3 variants where possible.
What other medicines interact with Siponimod?
MediHelp also lists interactions of Siponimod with, for example, Cladribine, Fingolimod, Fluconazole. The full list is on the Siponimod page.
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