Ziftomenib and Lefamulin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Lefamulin
Ziftomenib
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
Increased risk of QT interval prolongation, an increased ziftomenib exposure and an increased risk of ziftomenib-related adverse reaction
Interaction Deep Dive
Avoid coadministration of ziftomenib with strong or moderate CYP3A4 inhibitors with a known potential to prolong the QTc interval as it may increase ziftomenib exposure, which may increase the risk of adverse reactions such as QT prolongation. If concomitant use cannot be avoided, obtain ECGs when initiating, during concomitant use, and as clinically indicated. Interrupt ziftomenib if the QTc interval is more than 500 ms or the change from baseline is more than 60 ms. Concomitant use may also result in adverse reactions associated with QTc interval prolongation, including torsades de pointes, other serious arrhythmias, and sudden death. In drug interaction studies, itraconazole, voriconazole, and posaconazole (strong CYP3A4 inhibitors) are estimated to increase ziftomenib AUC by up to 3-fold and Cmax by up to 2-fold. Erythromycin, fluconazole, and isavuconazole (moderate CYP3A4 inhibitors) are estimated to increase ziftomenib AUC by up to 2-fold and Cmax by up to 2-fold. Monitor patients more frequently for ziftomenib-associated adverse reactions1.
Why it happens (mechanism)
Additive QT interval prolongation; inhibition of CYP3A4-mediated metabolism of ziftomenib
Literature reports
1 report — tap to read
a) In drug interaction studies, itraconazole, voriconazole, and posaconazole (strong CYP3A4 inhibitors) are estimated to increase ziftomenib AUC by up to 3-fold and Cmax by up to 2-fold. Erythromycin, fluconazole, and isavuconazole (moderate CYP3A4 inhibitors) are estimated to increase ziftomenib AUC by up to 2-fold and Cmax by up to 2-fold 1.
Common questions
Can I take Ziftomenib and Lefamulin together?
Increased risk of QT interval prolongation, an increased ziftomenib exposure and an increased risk of ziftomenib-related adverse reaction Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ziftomenib and Lefamulin 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 Ziftomenib or Lefamulin 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: KOMZIFTI™ oral capsules, ziftomenib oral capsules. Kura Oncology, Inc (per manufacturer), San Diego, CA, 2025. DailyMed
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