Momelotinib 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
Simvastatin
Momelotinib
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. Momelotinib (Ojjaara) can slow down one of the "pumps" in your body that normally helps move simvastatin (Zocor) out. When that pump is blocked, more simvastatin can build up in your system. Higher levels of a statin can mean a bit more risk of side effects, like muscle aches or muscle soreness.
I want to reassure you that this is based on how the drugs work in theory, not on lots of real-world reports. Your care team can manage it easily by adjusting your simvastatin dose or keeping a closer eye on you. Please don't stop either medicine on your own, just check in with your pharmacist or doctor.
Mechanism: Momelotinib inhibits BCRP-mediated efflux. Simvastatin (and its active acid) is a BCRP substrate, so co-administration may increase simvastatin exposure (AUC/Cmax) and raise the risk of statin-related adverse effects, notably myopathy and rhabdomyolysis.
- Direction: increased simvastatin exposure (increases drug effect).
- Evidence: theoretical; magnitude not quantified.
- Onset: unspecified.
Management: Consider adjusting (individualizing) the simvastatin dose when used with momelotinib. Monitor for muscle pain, weakness, and dark urine; check CK if myopathy is suspected. Reinforce that dose selection should be tailored by the care team.
What happens
Increased BCRP substrate exposure and an increased risk of BCRP substrate-related adverse reactions
Interaction Deep Dive
Because momelotinib acts as a BCRP inhibitor, giving it together with BCRP substrates may raise the exposure of those substrates and could heighten the likelihood of adverse reactions linked to them. If these agents are used at the same time, consider modifying the dose of the BCRP substrates1.
Why it happens (mechanism)
Inhibition of BCRP-mediated efflux transport by momelotinib
How to manage this interaction
The good news: this is very manageable with your care team.
- Keep taking both medicines exactly as prescribed unless your doctor or pharmacist tells you otherwise.
- Your team may adjust and individualize your simvastatin dose, or monitor you more closely, while you are on momelotinib.
- Watch for and promptly report muscle pain, tenderness, weakness, or dark-colored urine, since these can be signs of statin-related muscle effects.
- Bring an up-to-date medication list to appointments so your pharmacist can review it.
Don't stop or change either drug on your own, just raise any concerns with your prescriber.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In clinical trials, when a single 10 mg dose of rosuvastatin (a BCRP substrate) was given together with multiple doses of momelotinib (200 mg once daily), the Cmax of rosuvastatin rose by 220% and its AUC rose by 170% 1.
Common questions
Can I take Momelotinib and Simvastatin together?
Momelotinib may raise simvastatin levels, slightly increasing the chance of statin muscle side effects; keep taking both as prescribed and let your care team adjust the dose or monitor you, and report any muscle pain or weakness. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Momelotinib 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 Momelotinib and Simvastatin interaction managed?
The good news: this is very manageable with your care team. Keep taking both medicines exactly as prescribed unless your doctor or pharmacist tells you otherwise. Your team may adjust and individualize your simvastatin dose, or monitor you more closely, while you are on momelotinib. Watch for and promptly report muscle pain, tenderness, weakness, or dark-colored urine, since these can be signs of… 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 Momelotinib 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 (1)
- Product Information: OJJAARA oral tablets, momelotinib oral route. GlaxoSmithKline (per FDA), Durham, NC, 2023. DailyMed
Keep reading about Simvastatin
Keep reading about Momelotinib
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