Drug Interaction Report

Pimavanserin and Arsenic Trioxide: Interaction Details

A pharmacist-reviewed analysis of the Pimavanserin and Arsenic Trioxide interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Pimavanserin

Nuplazid Nuplazid®
+

Arsenic Trioxide

Trisenox
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Jul 11, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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.

Of 71 documented Pimavanserin interactions, 67 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
unspecified
Evidence
theoretical
Severity
Major

What happens

An increased risk of QT interval prolongation

Interaction Deep Dive

Clinically significant QT-interval prolongation has occurred at the usual pimavanserin dosage. Avoid concomitant use of pimavanserin with other agents that prolong the QT interval due to the potential for additive effects on the QT interval and an increased risk of cardiac arrhythmia1.

Why it happens (mechanism)

Additive QT interval prolongation

Common questions

Can I take Pimavanserin and Arsenic Trioxide together?

An increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.

How serious is the Pimavanserin and Arsenic Trioxide 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 Pimavanserin or Arsenic Trioxide 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)

  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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