Belumosudil and Lumacaftor: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 15, 2026 · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Lumacaftor
No brand names on recordBelumosudil
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.
You've been prescribed belumosudil (Rezurock) along with lumacaftor. Here's the plain-English version: lumacaftor speeds up a liver enzyme (called CYP3A) that breaks down belumosudil. When belumosudil gets cleared out faster, less of it stays in your body, so it may not work as well against your condition.
The good news is this is very manageable. Your care team knows about this and can adjust your belumosudil dose so you still get the benefit you need. Please don't change anything on your own. Just keep taking both as prescribed and check in with your pharmacist or doctor so they can tailor your dose.
Effect: Lumacaftor is a strong CYP3A inducer; belumosudil is a CYP3A substrate. Coadministration is expected to increase belumosudil metabolism, reducing exposure and efficacy.
Magnitude: With rifampin (reference strong inducer), belumosudil Cmax fell ~59% and AUC ~72%.
Evidence: Probable. Severity: Major. Onset: Unspecified.
- Neither drug is a prodrug; loss of efficacy is the concern, not toxicity.
- Per labeling, increase belumosudil to 200 mg twice daily when given with a strong CYP3A inducer.
- Monitor clinical response (e.g., cGVHD control).
What happens
Reduced belumosudil exposure and reduced efficacy of belumosudil
Interaction Deep Dive
When belumosudil, a CYP3A substrate, is given together with a potent CYP3A inducer, belumosudil exposure may fall, potentially lessening its therapeutic effect. A drug interaction trial conducted in healthy volunteers showed that pairing belumosudil with rifAMPin, a strong CYP3A inducer, lowered belumosudil Cmax by 59% and AUC by 72%. When belumosudil is used alongside a strong CYP3A inducer, raise the belumosudil dose to 200 mg twice daily1.
Why it happens (mechanism)
Induction of CYP3A-mediated belumosudil metabolism
How to manage this interaction
This interaction is well understood and your care team can manage it.
- Keep taking both medications as prescribed unless your prescriber tells you otherwise.
- Because lumacaftor can lower belumosudil levels, the documented approach is to increase belumosudil to 200 mg twice daily when the two are used together. Your team will make and individualize this decision.
- Your team may also watch your response to belumosudil more closely to be sure it is still working.
Ask your pharmacist or prescriber to confirm your correct belumosudil dose before combining these, and report any worsening of the condition belumosudil is treating.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a drug interaction study conducted in healthy subjects, giving belumosudil together with rifAMPin (a strong CYP3A inducer) reduced belumosudil Cmax by 59% and AUC by 72% 1.
Common questions
Can I take Belumosudil and Lumacaftor together?
Lumacaftor can speed up the breakdown of belumosudil and make it less effective; your care team can manage this, often by increasing belumosudil to 200 mg twice daily. Don't change doses yourself, confirm the right dose with your prescriber or pharmacist. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Belumosudil and Lumacaftor 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 Belumosudil and Lumacaftor interaction managed?
This interaction is well understood and your care team can manage it. Keep taking both medications as prescribed unless your prescriber tells you otherwise. Because lumacaftor can lower belumosudil levels, the documented approach is to increase belumosudil to 200 mg twice daily when the two are used together. Your team will make and individualize this decision. Your team may also watch your respon… 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.
Questions for your pharmacist
- Does my dose of Belumosudil or Lumacaftor 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: REZUROCK(R) oral tablets, belumosudil oral tablets. Kadmon Pharmaceuticals LLC (per FDA), Bridgewater, NJ, 2024. DailyMed
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