Atrasentan and Letermovir Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Letermovir Injection
Atrasentan
No brand names on record
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 atrasentan exposure and an increased risk of atrasentan-related adverse reactions
Interaction Deep Dive
Avoid concomitant use of atrasentan (OATP1B1 and OATP1B3 substrate) with OATP1B1/OATP1B3 inhibitors as it may increase atrasentan exposure, which may increase the risk of atrasentan adverse reactions. In a drug interaction study, atrasentan Cmax was 4.3 times as high and AUC was 3.8 times as high following coadministration of a single dose of 0.75 mg atrasentan with cycloSPORINE (OATP1B1/1B3 inhibitor)1.
Why it happens (mechanism)
Inhibition of OATP1B1-mediated efflux transport of atrasentan; inhibition of OATP1B3-mediated efflux transport of atrasentan
Literature reports
1 report — tap to read
a) In a drug interaction study, atrasentan Cmax was 4.3 times as high and AUC was 3.8 times as high following coadministration of a single dose of 0.75 mg atrasentan with cycloSPORINE (OATP1B1/1B3 inhibitor) 1.
Common questions
Can I take Atrasentan and Letermovir Injection together?
Increased atrasentan exposure and an increased risk of atrasentan-related adverse reactions Always confirm with your pharmacist or prescriber before making any change.
How serious is the Atrasentan 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 Atrasentan 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: VANRAFIA(TM) oral tablets, atrasentan oral tablets. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2025. DailyMed
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