Daridorexant and Letermovir Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Daridorexant
No brand names on recordLetermovir 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
Increased daridorexant exposure
Interaction Deep Dive
Concomitant use of daridorexant (CYP3A4 substrate) with a moderate CYP3A4 inhibitor increases exposure to daridorexant, which may increase the risk of adverse reactions. Concomitant use of daridorexant and dilTIAZem significantly increased daridorexant AUC and Cmax. If used concomitantly, the dose of daridorexant should not exceed 25 mg once per night1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated daridorexant metabolism
Literature reports
1 report — tap to read
a) Concomitant use of daridorexant 25 mg and dilTIAZem (moderate CYP3A4 inhibitor) 240 mg increased daridorexant AUC by a geometric mean ratio (GMR) of 2.4 (90% CI, 2 to 2.8) and Cmax by a GMR of 1.4 (90% CI, 1.2 to 1.6) 1.
Common questions
Can I take Daridorexant and Letermovir Injection together?
Increased daridorexant exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Daridorexant and Letermovir Injection 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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Daridorexant or Letermovir Injection 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 (1)
- Product Information: QUVIVIQ(R) oral tablets, daridorexant oral tablets. Idorsia Pharmaceuticals US Inc (per FDA), Radnor, PA, 2023. DailyMed
Keep reading about Daridorexant
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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