Orforglipron and Nafcillin Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Nafcillin Injection
Orforglipron
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 orforglipron exposure and reduced efficacy of orforglipron
Interaction Deep Dive
Concomitant use of orforglipron with moderate CYP3A4 inducers may reduce orforglipron exposure, which may reduce the effectiveness of orforglipron. In drug interaction studies, concomitant use of orforglipron with efavirenz (moderate CYP3A4 inducer) (600 mg twice daily), which was simulated using physiologically based pharmacokinetic modeling, reduced the orforglipron AUC by 61%, and Cmax by 33%. Monitor orforglipron effectiveness and escalate dosage as needed when used concomitantly with moderate CYP3A4 inducers1.
Why it happens (mechanism)
Induction of CYP3A4-mediated metabolism of orforglipron
Literature reports
1 report — tap to read
a) In drug interaction studies, concomitant use of orforglipron with efavirenz (moderate CYP3A4 inducer) (600 mg twice daily), which was simulated using physiologically based pharmacokinetic modeling, reduced the orforglipron AUC by 61%, and Cmax by 33% 1.
Common questions
Can I take Orforglipron and Nafcillin Injection together?
Reduced orforglipron exposure and reduced efficacy of orforglipron Always confirm with your pharmacist or prescriber before making any change.
How serious is the Orforglipron and Nafcillin Injection 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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Orforglipron or Nafcillin Injection 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: FOUNDAYO™ oral tablet, orforglipron oral tablet. Lilly USA LLC, Indianapolis, IN, 2026. DailyMed
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