Letermovir Injection and Lomitapide: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Lomitapide
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 lomitapide exposure
Interaction Deep Dive
Concomitant use of lomitapide (a CYP3A4 substrate) with a moderate CYP3A4 inhibitor is contraindicated, as coadministration may result in significantly increased exposure of lomitapide. Although the interaction between lomitapide and moderate CYP3A4 inhibitors has not been studied, the concomitant use of a strong CYP3A4 inhibitor (ketoconazole 200 mg twice daily for 9 days) with lomitapide (60 mg daily) resulted in a 27-fold increase in lomitapide AUC and a 15-fold increase in lomitapide Cmax. One patient had markedly elevated transaminases (ie, ALT and AST) within days of initiating clarithromycin, a strong CYP3A4 inhibitor, during lomitapide clinical trials. If treatment with a moderate CYP3A4 inhibitor is unavoidable, discontinue lomitapide during the course of treatment1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of lomitapide
Literature reports
2 reports — tap to read
a) During lomitapide clinical trials, a patient with homozygous familial hypercholesterolemia (HoFH) had markedly elevated transaminases (ALT, 24 times ULN; AST, 13 times ULN) within days of initiating clarithromycin, a strong CYP3A4 inhibitor 1.
b) In a drug interaction study, concomitant use of a strong CYP3A4 inhibitor (ketoconazole 200 mg twice daily for 9 days) with lomitapide (60 mg daily) resulted in a 27-fold increase in lomitapide AUC and a 15-fold increase in lomitapide Cmax 1.
Common questions
Can I take Letermovir Injection and Lomitapide together?
Increased lomitapide exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Letermovir Injection and Lomitapide interaction?
It is rated contraindicated. These should generally not be used together.
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 Lomitapide 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: JUXTAPID® oral capsules, lomitapide oral capsules. Chiesi USA, Inc. (per Manufacturer), Cary, NC, 2026. DailyMed
Keep reading about Lomitapide
Keep reading about Letermovir Injection
These medications also interact with supplements
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist