Letermovir Injection and Eplerenone: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Eplerenone
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
Increased eplerenone plasma concentrations
Interaction Deep Dive
Eplerenone is primarily metabolized via the CYP3A isozyme. When eplerenone was coadministered with moderate CYP3A inhibitors (eg, erythromycin 500 mg twice daily, verapamil 240 mg once daily, saquinavir 1200 mg 3 times daily, or fluconazole 200 mg once daily), the eplerenone Cmax increased by 40% to 60% and the eplerenone AUC increased by 100% to 190%. Concomitant use of eplerenone and a moderate CYP3A inhibitor is not recommended due to the potential for significantly elevated eplerenone plasma concentrations. If concurrent use is unavoidable, do not exceed a dosage of 25 mg once daily in patients with congestive heart failure following a myocardial infarction. For patients with hypertension, initiate dosing with 25 mg once daily and do not exceed a dosage of 25 mg twice daily1.
Why it happens (mechanism)
Inhibition of CYP3A-mediated eplerenone metabolism
Common questions
Can I take Letermovir Injection and Eplerenone together?
Increased eplerenone plasma concentrations Always confirm with your pharmacist or prescriber before making any change.
How serious is the Letermovir Injection and Eplerenone 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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Letermovir Injection or Eplerenone 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: INSPRA(R) oral tablets, eplerenone oral tables. GD Searle (per FDA), New York, NY, 2016. DailyMed
Keep reading about Eplerenone
Keep reading about Letermovir Injection
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