Drug interactions
Ketoconazole + Lefamulin
Severity: Major
Ketoconazole and Lefamulin: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Ketoconazole increases lefamulin exposure, which may prolong the QT interval. Ketoconazole itself also carries QT risk, so effects may be additive.
What this interaction means in plain words
Ketoconazole and Lefamulin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Ketoconazole belongs to Anti Fungals; Lefamulin belongs to Anti Bacterial.
Why it happens
Strong CYP3A4 (and P-gp) inhibition by ketoconazole reduces lefamulin clearance, adding to additive QT effects.
What to do
Avoid combining oral lefamulin with strong CYP3A and P-gp inhibitors. If use is needed, use another antibiotic or monitor ECG.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Other interactions of Lefamulin
- Lefamulin + Methadone Contraindicated
- Lefamulin + Pimavanserin Contraindicated
- Lefamulin + Pimozide Contraindicated
- Lefamulin + Quinidine Contraindicated
- Alfuzosin + Lefamulin Major
- Amiodarone + Lefamulin Major
Frequently asked questions
Can I take Ketoconazole with Lefamulin?
MediHelp rates the interaction as major. Ketoconazole and Lefamulin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Ketoconazole increases lefamulin exposure, which may prolong the QT interval. Ketoconazole itself also carries QT risk, so effects may be additive.
How serious is the interaction between Ketoconazole and Lefamulin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid combining oral lefamulin with strong CYP3A and P-gp inhibitors. If use is needed, use another antibiotic or monitor ECG.
What other medicines interact with Ketoconazole?
MediHelp also lists interactions of Ketoconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Ketoconazole page.
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