Lomitapide and Simvastatin: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 4, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Lomitapide
No brand names on recordSimvastatin
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.
Let me walk you through this one. Lomitapide slows down the liver enzyme that normally breaks down simvastatin (a cholesterol medicine). When that enzyme is slowed, more simvastatin builds up in your body than usual. In fact, studies showed simvastatin levels roughly doubled when the two were taken together.
Higher statin levels raise the chance of muscle problems, like unexplained muscle pain, tenderness, or weakness. In rare cases this can become serious muscle breakdown (rhabdomyolysis). The good news is this is well understood and easy to plan for. Your care team will usually lower your simvastatin dose and keep an eye on you. Tell them right away if you notice new muscle aches or dark-colored urine.
Effect: Lomitapide inhibits CYP3A4, reducing simvastatin metabolism and increasing systemic exposure, raising myopathy/rhabdomyolysis risk. Simvastatin is a CYP3A4 substrate (its active acid forms in vivo), so reduced clearance increases both parent and active moiety exposure.
Magnitude: With simvastatin 40 mg, AUC and Cmax rose 99% and 102% (simvastatin acid 71%/57%); with 20 mg, AUC/Cmax rose 62%/65% (acid 39%/35%). Dose-related.
Evidence: Probable. Severity: Major.
- On initiating lomitapide, reduce simvastatin dose by 50%.
- Limit simvastatin to 20 mg/day (40 mg/day only if previously on 80 mg chronically).
- Monitor for myopathy; discontinue simvastatin if suspected or confirmed.
What happens
Increased simvastatin exposure and an increased risk of myopathy and rhabdomyolysis
Interaction Deep Dive
Taking lomitapide together with simvastatin produces dose-dependent elevations in simvastatin exposure, which can heighten the likelihood of myopathy, including rhabdomyolysis. When lomitapide was given alongside simvastatin 40 mg, the AUC and Cmax of simvastatin rose by 99% and 102%, and those of simvastatin acid rose by 71% and 57%, respectively; with simvastatin 20 mg, the AUC and Cmax of simvastatin increased by 62% and 65%, while simvastatin acid increased by 39% and 35%, respectively3. Upon initiating lomitapide, reduce the simvastatin dose by 50%. While the two drugs are used concurrently, keep simvastatin at no more than 20 mg per day, or up to 40 mg daily for patients who have chronically taken simvastatin 80 mg daily in the past. Stop simvastatin if myopathy is either diagnosed or suspected 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of simvastatin
How to manage this interaction
This interaction is manageable, and your care team has a clear plan for it. Keep taking both medications exactly as prescribed unless your doctor or pharmacist tells you otherwise.
- When lomitapide is started, the simvastatin dose is typically reduced by half.
- During treatment together, simvastatin is usually limited to 20 mg per day (or 40 mg per day only if you were previously stable on 80 mg long term).
- Report any muscle pain, tenderness, weakness, or dark urine promptly, as simvastatin may be stopped if a muscle problem is suspected.
Ask your pharmacist to confirm your current simvastatin dose fits these limits.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
3 reports — tap to read
a) When a single 40 mg dose of simvastatin was given alongside lomitapide 60 mg daily for 7 days, simvastatin AUC rose by 99% and Cmax by 102%, while simvastatin acid AUC rose by 71% and Cmax by 57%; in contrast, a single 20 mg dose of simvastatin administered with lomitapide 10 mg daily for 7 days raised simvastatin AUC by 62% and Cmax by 65% and simvastatin acid AUC by 39% and Cmax by 35% 3.
b) In a drug interaction study, the combined use of lomitapide 60 mg once daily with a single 40 mg dose of simvastatin over 7 days led to increases in simvastatin and simvastatin acid AUC exposure of 1.7-fold and 2-fold and in Cmax of 1.6-fold and 2-fold, respectively 2.
c) In a drug interaction study, the combined use of lomitapide 10 mg once daily with a single 20 mg dose of simvastatin over 7 days led to increases in simvastatin and simvastatin acid AUC exposure of 1-4 fold and 1.6-fold and in Cmax of 1.4-fold and 1.7-fold, respectively 2.
Common questions
Can I take Lomitapide and Simvastatin together?
Lomitapide raises simvastatin levels and the risk of muscle injury, so your simvastatin dose is usually cut and capped (20 mg/day, or 40 mg if previously on 80 mg). Report muscle pain or dark urine right away. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lomitapide and Simvastatin 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 is the Lomitapide and Simvastatin interaction managed?
This interaction is manageable, and your care team has a clear plan for it. Keep taking both medications exactly as prescribed unless your doctor or pharmacist tells you otherwise. When lomitapide is started, the simvastatin dose is typically reduced by half. During treatment together, simvastatin is usually limited to 20 mg per day (or 40 mg per day only if you were previously stable on 80 mg lon… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Lomitapide or Simvastatin 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 (3)
- Product Information: ZOCOR(R) oral tablets, simvastatin oral tablets. Organon & Co (per FDA), Jersey City, NJ, 2022. DailyMed
- Product Information: VYTORIN(R) oral tablets, ezetimibe simvastatin oral tablets. Organon LLC (per FDA), Jersey City, NJ, 2024. DailyMed
- Product Information: JUXTAPID® oral capsules, lomitapide oral capsules. Chiesi USA, Inc. (per Manufacturer), Cary, NC, 2026. DailyMed
Keep reading about Lomitapide
Keep reading about Simvastatin
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