Ivosidenib 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
Ivosidenib
Simvastatin
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.
Here's what's going on. Ivosidenib (Tibsovo) is a cancer medicine that can speed up the liver enzyme your body uses to break down simvastatin (Zocor). When that enzyme works faster, your body clears simvastatin more quickly, so there's less of it around to lower your cholesterol.
The main worry here isn't a dangerous side effect. It's that your simvastatin may simply not work as well, leaving your cholesterol higher than you and your doctor want. The good news is this is very manageable. Keep taking both exactly as prescribed, and let your care team know you're on both so they can check your cholesterol and adjust your plan if needed.
Mechanism: Ivosidenib is a CYP3A4 inducer; simvastatin is a sensitive CYP3A4 substrate. Induction increases simvastatin metabolism, lowering its plasma exposure (AUC/Cmax) and potentially reducing lipid-lowering efficacy.
- Direction: reduced simvastatin effect (loss of efficacy), not increased toxicity.
- Evidence: theoretical; magnitude not quantified.
- Onset: unspecified (enzyme induction is typically gradual over days to weeks).
- Management: avoid coadministration or use an alternative lipid-lowering agent where feasible. If unavoidable, monitor lipid panel for loss of therapeutic effect and individualize dosing with the care team.
What happens
Reduced exposure of sensitive CYP3A4 substrates and risk of loss of efficacy
Interaction Deep Dive
Taking ivosidenib (a CYP3A4 inducer) together with a sensitive CYP3A4 substrate can lower the exposure of that sensitive substrate, potentially reducing its effectiveness. This combination should be avoided, or alternative treatments should be substituted. When the concurrent use is unavoidable, watch patients for any absence of the intended therapeutic response to the sensitive CYP3A4 substrate1.
Why it happens (mechanism)
Induction of CYP3A4-mediated substrate metabolism by ivosidenib
How to manage this interaction
Keep taking both medicines as prescribed unless your care team tells you otherwise. This interaction is usually handled by monitoring and adjusting, not by stopping anything on your own.
- Your team may check your cholesterol (lipid panel) to make sure the simvastatin is still working.
- They may consider an alternative cholesterol medicine that is less affected, or adjust your plan.
- Your simvastatin dose may need to be individualized by your care team based on your results.
Tell your pharmacist or prescriber that you take both drugs, so they can watch for any rise in your cholesterol.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) After a single oral 375 mg dose of aprepitant was given on Day 9 during a 14-day course of rifAMPin 600 mg/day, a potent CYP3A4 inducer, the aprepitant AUC fell by roughly 11-fold and the mean terminal half-life was reduced by about 3-fold 2.
Common questions
Can I take Ivosidenib and Simvastatin together?
Ivosidenib can make simvastatin work less well by clearing it faster, so your cholesterol may not stay controlled. Don't change anything yourself, but ask your care team to monitor your cholesterol and adjust your plan if needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ivosidenib 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 Ivosidenib and Simvastatin interaction managed?
Keep taking both medicines as prescribed unless your care team tells you otherwise. This interaction is usually handled by monitoring and adjusting, not by stopping anything on your own. Your team may check your cholesterol (lipid panel) to make sure the simvastatin is still working. They may consider an alternative cholesterol medicine that is less affected, or adjust your plan. Your simvastatin… Management is individual — always follow your own care team's guidance.
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 Ivosidenib 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 (2)
Keep reading about Ivosidenib
Keep reading about Simvastatin
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.
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