Pimavanserin and Nafcillin Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Pimavanserin
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 pimavanserin exposure and reduced efficacy of pimavanserin
Interaction Deep Dive
Avoid concomitant use of moderate CYP3A4 inducers with pimavanserin. Concomitant use of pimavanserin and a strong CYP3A4 inducer reduces pimavanserin exposure. In a simulation of pimavanserin with a moderate CYP3A4 inducer (efavirenz), physiologically based pharmacokinetic (PBPK) models predicted pimavanserin Cmax and AUC at steady state decreased by approximately 60% and 70%, respectively1.
Why it happens (mechanism)
Induction of CYP3A4-mediated pimavanserin metabolism
Literature reports
1 report — tap to read
a) In a simulation of pimavanserin with a moderate CYP3A4 inducer (efavirenz), physiologically based pharmacokinetic (PBPK) models predicted pimavanserin Cmax and AUC at steady state decreased by approximately 60% and 70%, respectively 1.
Common questions
Can I take Pimavanserin and Nafcillin Injection together?
Reduced pimavanserin exposure and reduced efficacy of pimavanserin Always confirm with your pharmacist or prescriber before making any change.
How serious is the Pimavanserin 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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Pimavanserin 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: NUPLAZID(R) oral capsules, oral tablets, pimavanserin oral capsules, oral tablets. Acadia Pharmaceuticals Inc (per manufacturer), San Diego, CA, 2023. DailyMed
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