Avacopan and Buprenorphine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Avacopan
Buprenorphine
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. Avacopan (Tavneos) can slow down a liver enzyme called CYP3A4. Buprenorphine (Belbuca, Butrans, Sublocade, and others) is partly broken down by that same enzyme. So taking them together may let more buprenorphine build up in your body than usual.
Buprenorphine is an opioid, so higher levels could mean more drowsiness, dizziness, nausea, or slowed breathing. Please don't change anything on your own. This is theoretical, meaning it's based on how the drugs behave rather than lots of real-world reports. Your care team can manage it by adjusting your dose and watching how you feel.
Mechanism: Avacopan inhibits CYP3A4, reducing metabolism of CYP3A4 substrates. Buprenorphine undergoes CYP3A4-mediated metabolism (to norbuprenorphine); it is not a prodrug, so inhibition is expected to increase buprenorphine exposure.
- Direction: Increased AUC/Cmax of buprenorphine, raising risk of opioid effects (sedation, respiratory depression).
- Magnitude: Not quantified for buprenorphine; avacopan raised simvastatin AUC ~3.5-fold and midazolam AUC ~1.55-fold.
- Evidence: Theoretical/extrapolated. Onset unspecified.
- Management: Consider reduced buprenorphine dosing; monitor for sedation and respiratory status. Individualize.
What happens
Increased CYP3A4 substrate exposure
Interaction Deep Dive
Taking avacopan alongside a CYP3A4 substrate can raise the exposure to that substrate. When simvastatin (a CYP3A4 substrate) was given together with avacopan at 60 mg daily for 7 days following food, the simvastatin AUC rose 3.53-fold and its Cmax rose 3.20-fold. Similarly, when midazolam (a CYP3A4 substrate) was combined with avacopan at 30 mg daily for 11 days on an empty stomach, the AUC and Cmax of simvastatin increased 1.55-fold and 1.81-fold respectively. Dose reduction of CYP3A4 substrates should be considered when they are given together with avacopan1.
Why it happens (mechanism)
Inhibition of CYP3A4-substrate metabolism by avacopan
How to manage this interaction
The good news: your care team can handle this by tailoring your treatment.
- Keep taking both medications exactly as prescribed unless your prescriber tells you otherwise.
- Your buprenorphine dose may need to be adjusted and individualized by your care team, and they may monitor you more closely while you're on both.
- Watch for and report increased drowsiness, dizziness, confusion, nausea, or slowed or shallow breathing.
- Tell your pharmacist and prescriber that you take both, so they can plan ahead.
Do not stop or change either drug on your own.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) When simvastatin (a CYP3A4 substrate) was given together with avacopan at 60 mg daily for 7 days following food, the AUC and Cmax of simvastatin rose by 3.53-fold and 3.20-fold, respectively 1.
b) When midazolam (a CYP3A4 substrate) was given together with avacopan at 30 mg daily for 11 days on an empty stomach, the AUC and Cmax of simvastatin rose by 1.55-fold and 1.81-fold, respectively 1.
Common questions
Can I take Avacopan and Buprenorphine together?
Avacopan can raise buprenorphine levels by slowing its breakdown, which may increase opioid side effects, so your care team may lower your dose and watch you more closely. Report any unusual drowsiness or slowed breathing to your pharmacist or doctor. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Avacopan and Buprenorphine 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 Avacopan and Buprenorphine interaction managed?
The good news: your care team can handle this by tailoring your treatment. Keep taking both medications exactly as prescribed unless your prescriber tells you otherwise. Your buprenorphine dose may need to be adjusted and individualized by your care team, and they may monitor you more closely while you're on both. Watch for and report increased drowsiness, dizziness, confusion, nausea, or slowed o… 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.
Questions for your pharmacist
- Does my dose of Avacopan or Buprenorphine 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: TAVNEOS(R) oral capsules, avacopan oral capsules. ChemoCentryx Inc (per FDA), Thousand Oaks, CA, 2024. DailyMed
Keep reading about Avacopan
Keep reading about Buprenorphine
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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