Drug interactions
Ketoconazole + Larotrectinib
Severity: Major
Ketoconazole and Larotrectinib: 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 larotrectinib exposure and may worsen adverse effects such as liver enzyme elevation, neurotoxicity, and myelosuppression.
What this interaction means in plain words
Ketoconazole and Larotrectinib 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; Larotrectinib belongs to Oncology.
Why it happens
Strong CYP3A4 inhibition by ketoconazole decreases larotrectinib metabolism.
What to do
Avoid if possible; otherwise reduce larotrectinib dose by 50% and monitor for toxicity. Resume the prior dose after the inhibitor is stopped for 3 to 5 half-lives.
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 Larotrectinib
Frequently asked questions
Can I take Ketoconazole with Larotrectinib?
MediHelp rates the interaction as major. Ketoconazole and Larotrectinib 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 larotrectinib exposure and may worsen adverse effects such as liver enzyme elevation, neurotoxicity, and myelosuppression.
How serious is the interaction between Ketoconazole and Larotrectinib?
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 if possible; otherwise reduce larotrectinib dose by 50% and monitor for toxicity. Resume the prior dose after the inhibitor is stopped for 3 to 5 half-lives.
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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