Valspodar and Mitoxantrone Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Mitoxantrone Injection
Valspodar
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 mitoXANTRONE toxicity
Interaction Deep Dive
A prolongation of the elimination half-life of mitoXANTRONE (1.8-fold) and an increase in its area under the concentration-time curve (AUC) have been observed during combined administration of valspodar with the MEC regimen (mitoXANTRONE, etoposide, and cytarabine) in acute myelogenous leukemia patients. These changes in mitoXANTRONE pharmacokinetics were associated with increased toxicity1. Enhanced toxicity of mitoXANTRONE when given with valspodar has also been observed in another study with a similar patient population, although effects of valspodar on mitoXANTRONE serum levels were variable 2. Dose reductions of 20% to 66% have been required for mitoXANTRONE when given with valspodar. The mechanism of this interaction is unclear.
Why it happens (mechanism)
Impaired elimination of mitoXANTRONE due to p-glycoprotein inhibition
Common questions
Can I take Valspodar and Mitoxantrone Injection together?
An increased risk of mitoXANTRONE toxicity Always confirm with your pharmacist or prescriber before making any change.
How serious is the Valspodar and Mitoxantrone 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 "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
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 Valspodar or Mitoxantrone 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 (2)
- Advani R, Saba HI, Tallman MS, et al: Treatment of refractory and relapsed acute myelogenous leukemia with combination chemotherapy plus the multidrug resistance modulator PSC833 (valspodar). Blood 1999; 93:787-795.
- Kornblau SM, Estey E, Madden T, et al: Phase I study of mitoxantrone plus etoposide with multidrug blockade by SDZ PSC-833 in relapses or refractory acute myelogenous leukemia. J Clin Oncol 1997; 15:1796-1802.
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