Arsenic Trioxide Injection and Vepdegestrant: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Arsenic Trioxide Injection
Vepdegestrant
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
An increased risk of QT interval prolongation and an increased risk of torsade de pointes, polymorphic ventricular tachycardia, other serious arrhythmia symptoms
Interaction Deep Dive
Avoid concomitant use of vepdegestrant with other drugs with a known potential to prolong the QTc interval as it may result in a greater increase in the QTc interval and adverse reactions associated with QTc interval prolongation, including torsade de pointes, other serious arrhythmias, and sudden death. If concomitant use cannot be avoided, obtain ECGs when initiating and during concomitant use, and as clinically indicated. In patients with QTc greater than 480 ms or greater than 60 ms increase from baseline (less than or equal to 500 ms): Withhold vepdegestrant until QTc less than or equal to 480 ms and less than or equal to 60 ms above baseline. Treat reversible causes (eg, hypokalemia, hypomagnesemia), then resume vepdegestrant at the same dose. Initiate more frequent ECG monitoring. In patients with QTc greater than 500 ms: Withhold vepdegestrant until QTc less than or equal to 480 ms and less than 60 ms above baseline. If a reversible cause is identified and corrected, resume vepdegestrant at the same dose. If no reversible cause is identified, resume vepdegestrant at a reduced dose. Increase frequency of ECG monitoring and permanently discontinue vepdegestrant, if QTc greater than 500 ms recurs. In patients that develop torsade de pointes, polymorphic ventricular tachycardia, or serious arrhythmia symptoms: Permanently discontinue vepdegestrant1.
Why it happens (mechanism)
Additive QT interval prolongation
Common questions
Can I take Arsenic Trioxide Injection and Vepdegestrant together?
An increased risk of QT interval prolongation and an increased risk of torsade de pointes, polymorphic ventricular tachycardia, other serious arrhythmia symptoms Always confirm with your pharmacist or prescriber before making any change.
How serious is the Arsenic Trioxide Injection and Vepdegestrant 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 Arsenic Trioxide Injection or Vepdegestrant 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: VEPPANU oral tablet, vepdegestrant oral tablet. Pfizer Inc. New York, NY, 2026. DailyMed
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