Nafcillin Injection and Rilzabrutinib: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Rilzabrutinib
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 rilzabrutinib exposure and reduced efficacy of rilzabrutinib
Interaction Deep Dive
Avoid concomitant use of rilzabrutinib (CYP3A substrate) with moderate CYP3A inducers as it may reduce rilzabrutinib exposure, which may reduce rilzabrutinib efficacy. In a drug interaction study, coadministration of moderate CYP3A inducers (efavirenz, rifabutin) is predicted to reduce rilzabrutinib Cmax and AUC by up to 70% at steady state1.
Why it happens (mechanism)
Induction of CYP3A-mediated metabolism of rilzabrutinib
Literature reports
1 report — tap to read
a) In a drug interaction study, coadministration of moderate CYP3A inducers (efavirenz, rifabutin) is predicted to reduce rilzabrutinib Cmax and AUC by up to 70% at steady state 1.
Common questions
Can I take Nafcillin Injection and Rilzabrutinib together?
Reduced rilzabrutinib exposure and reduced efficacy of rilzabrutinib Always confirm with your pharmacist or prescriber before making any change.
How serious is the Nafcillin Injection and Rilzabrutinib 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 Rilzabrutinib 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: WAYRILZ™ oral tablets, rilzabrutinib oral tablets. Genzyme Corporation (per FDA), Cambridge, MA, 2025. DailyMed
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