Mobocertinib and Lefamulin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Mobocertinib
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
Increased risk of QT interval prolongation
Interaction Deep Dive
Oral lefamulin is contraindicated with sensitive CYP3A4 substrates that prolong the QT interval like mobocertinib. Concomitant administration of oral lefamulin with sensitive CYP3A4 substrates may result in increased sensitive CYP3A4 exposure, leading to QT prolongation and cases of torsades de pointes1. If concomitant use is unavoidable, monitor the QTc interval more frequently with ECGs 2.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by lefamulin; additive QT interval prolongation
Literature reports
1 report — tap to read
a) Mean AUC(0 to inf) and Cmax of midazolam were increased by approximately 200% and 100%, respectively, when oral midazolam (sensitive CYP3A4 substrate) was administered concomitantly with and at 2 or 4 hours after administration of oral lefamulin 1.
Common questions
Can I take Mobocertinib and Lefamulin together?
Increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Mobocertinib 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 Mobocertinib 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 (2)
- 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
- Product Information: EXKIVITY(TM) oral capsules, mobocertinib oral capsules. Takeda Pharmaceuticals America Inc (per FDA), Lexington, MA, 2021.
Keep reading about Mobocertinib
Keep reading about Lefamulin
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