Nafcillin Injection and Avacopan: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Avacopan
Nafcillin Injection
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.
What happens
Reduced avacopan exposure
Interaction Deep Dive
Avoid coadministration of avacopan with strong or moderate CYP3A4 inducers. Coadministration of avacopan with a strong or moderate CYP3A4 inducer decreases avacopan exposure1.
Why it happens (mechanism)
Induction of CYP3A4-mediated metabolism of avacopan
Literature reports
1 report — tap to read
a) Coadministration of avacopan, a CYP3A4 substrate, with rifAMPin, a strong CYP3A4 inducer, at a dosage of 600 mg once daily for 11 days compared with avacopan alone, decreased avacopan Cmax by 79% (ratio, 0.21; 90% CI, 0.18 to 0.25) and AUC by 93% (ratio, 0.07; 90% CI, 0.06 to 0.1) 1.
Common questions
Can I take Nafcillin Injection and Avacopan together?
Reduced avacopan exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Nafcillin Injection and Avacopan 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 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 Nafcillin Injection or Avacopan 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 Nafcillin Injection
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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