Ivosidenib and Lefamulin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ivosidenib
Lefamulin
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
Reduced lefamulin exposure, reduced efficacy of lefamulin, an increased ivosidenib exposure, an increased risk of ivosidenib-related toxicities associated with cardiac conduction and an increased risk of interval QT prolongation
Interaction Deep Dive
Oral lefamulin is contraindicated with CYP3A4 substrates that prolong the QT interval, such as ivosidenib. Concomitant use may result in increased ivosidenib exposure, leading to QT prolongation and cases of torsades de pointes. Concomitant use of lefamulin injection with ivosidenib does not affect the ivosidenib exposure .If coadministered, monitor ECG during treatment. Concomitant use of lefamulin and ivosidenib (strong CYP3A4 inducer) may also reduce lefamulin exposure and may reduce efficacy of lefamulin. Oral rifAMPin (a strong CYP3A4 inducer) reduced the mean lefamulin AUC and Cmax by 28% and 8%, respectively, when administered concomitantly with IV lefamulin. Additionally, oral rifAMPin reduced the mean lefamulin AUC and Cmax by 72% and 57%, respectively, when administered concomitantly with oral lefamulin1.
Why it happens (mechanism)
Induction of CYP3A4-mediated metabolism of lefamulin; additive QT interval prolongation; inhibition of CYP3A4-mediated metabolism of ivosidenib
Literature reports
1 report — tap to read
a) Oral rifAMPin (a strong CYP3A4 inducer) reduced the mean lefamulin AUC(0 to inf) and Cmax by 28% and 8%, respectively, when administered concomitantly with IV lefamulin. Additionally, oral rifAMPin reduced the mean lefamulin AUC(0 to inf) and Cmax by 72% and 57%, respectively, when administered concomitantly with oral lefamulin 1.
Common questions
Can I take Ivosidenib and Lefamulin together?
Reduced lefamulin exposure, reduced efficacy of lefamulin, an increased ivosidenib exposure, an increased risk of ivosidenib-related toxicities associated with cardiac conduction and an increased risk of interval QT prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ivosidenib and Lefamulin interaction?
It is rated contraindicated. These should generally not be used together.
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 Ivosidenib 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: XENLETA(R) oral tablets, intravenous injection, lefamulin oral tablets, intravenous injection. Nabriva Therapeutics US Inc (per FDA), King of Prussia, PA, 2021. DailyMed
Keep reading about Ivosidenib
Keep reading about Lefamulin
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