Drug interactions
Cyclophosphamide + Letermovir
Severity: Moderate
Cyclophosphamide 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 is a moderate CYP3A inhibitor and also induces CYP2C9 and CYP2C19, which may alter cyclophosphamide metabolism. The clinical effect on active metabolite exposure is uncertain.
What this interaction means in plain words
Cyclophosphamide 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.
Cyclophosphamide belongs to Oncology; Letermovir belongs to Anti Virals.
Why it happens
Letermovir inhibits CYP3A and may induce CYP2C19, potentially changing cyclophosphamide bioactivation and clearance.
What to do
Monitor blood counts and clinical toxicity or response during concurrent use in transplant settings. No routine dose change is defined.
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 Cyclophosphamide
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 Cyclophosphamide with Letermovir?
MediHelp rates the interaction as moderate. Cyclophosphamide 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 is a moderate CYP3A inhibitor and also induces CYP2C9 and CYP2C19, which may alter cyclophosphamide metabolism. The clinical effect on active metabolite exposure is uncertain.
How serious is the interaction between Cyclophosphamide 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: Monitor blood counts and clinical toxicity or response during concurrent use in transplant settings. No routine dose change is defined.
What other medicines interact with Cyclophosphamide?
MediHelp also lists interactions of Cyclophosphamide with, for example, Adenovirus types 4 and 7 live, Belatacept, Bendamustine. The full list is on the Cyclophosphamide page.
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