Ibritumomab Injection and Defibrotide: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ibritumomab Injection
Defibrotide
No brand names on record
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 bleeding and hemorrhage
Interaction Deep Dive
Concomitant use of ibritumomab tiuxetan and an anticoagulant may increase the risk of major bleeding events. If coadministration is required, more frequent monitoring for thrombocytopenia is recommended1.
Why it happens (mechanism)
Unknown
Common questions
Can I take Ibritumomab Injection and Defibrotide together?
An increased risk of bleeding and hemorrhage Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ibritumomab Injection and Defibrotide interaction?
It is rated moderate. Can be significant — usually manageable with 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 Ibritumomab Injection or Defibrotide 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 anything you'd monitor while I'm on both?
References (1)
- Product Information: ZEVALIN(R) IV kit, ibritumomab tiuxetan IV kit. Biogen Idec Inc, Cambridge, MA, 2007.
Keep reading about Ibritumomab Injection
Keep reading about Defibrotide
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