Buthionine Sulfoximine and Melphalan: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Melphalan
Buthionine Sulfoximine
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 increase in melphalan bioavailability and toxicity
Interaction Deep Dive
A significant decrease in the volume of distribution (25 to 22 L/m(2)) and total body clearance (509 to 343 mL/minute/m(2)) of melphalan has been observed during combined administration with buthionine sulfoximine in advanced cancer patients. The area under the concentration-time curve (AUC) of melphalan was also increased significantly1. Myelosuppression has been greater with combined use of these agents compared to melphalan alone, possibly related to this interaction. The mechanism is unknown.
Why it happens (mechanism)
Unknown
Common questions
Can I take Buthionine Sulfoximine and Melphalan together?
An increase in melphalan bioavailability and toxicity Always confirm with your pharmacist or prescriber before making any change.
How serious is the Buthionine Sulfoximine and Melphalan interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
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 Buthionine Sulfoximine or Melphalan 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)
- Bailey HH, Mulcahy T, Tutsch KD, et al: Phase-I clinical trial of intravenous L-buthionine sulfoximine and melphalan: an attempt at modulation of glutathione. J Clin Oncol 1994; 12:194-205. DOI
Keep reading about Melphalan
Keep reading about Buthionine Sulfoximine
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