Letermovir Injection and Apalutamide: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Apalutamide
Letermovir Injection
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Reduced letermovir exposure and reduced efficacy of letermovir
Interaction Deep Dive
Coadministration of letermovir and apalutamide is not recommended as it may reduce the exposure of letermovir1, and reduce the efficacy of letermovir (OATP1B1/P-gp substrate). Consider alternative agents when possible or evaluate for loss of activity of the substrate if concomitant use cannot be avoided 2.
Why it happens (mechanism)
Induction of P-gp mediated efflux transport of letermovir; induction of OATP1B1-mediated efflux transport of letermovir
Literature reports
2 reports — tap to read
a) Coadministration of apalutamide with single oral doses of transporter substrates resulted in a 41% decrease in the AUC of rosuvastatin (a OATP1B1 substrate) 2.
b) Coadministration of apalutamide with single oral doses of transporter substrates resulted in a 30% decrease in the AUC of fexofenadine (a P-gp substrate) 2.
Common questions
Can I take Letermovir Injection and Apalutamide together?
Reduced letermovir exposure and reduced efficacy of letermovir Always confirm with your pharmacist or prescriber before making any change.
How serious is the Letermovir Injection and Apalutamide interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Letermovir Injection or Apalutamide need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (2)
- Product Information: PREVYMIS(R) oral tablets, oral pellets, intravenous injection, letermovir oral tablets, oral pellets, intravenous injection. Merck Sharp & Dohme Corp (per FDA), Rahway, NJ, 2024. DailyMed
- Product Information: ERLEADA® oral tablets, apalutamide oral tablets. Janssen Products LP (per FDA), Horsham, PA, 2026. DailyMed
Keep reading about Apalutamide
Keep reading about Letermovir Injection
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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