Drug interactions
Larotrectinib + Posaconazole
Severity: Major
Larotrectinib and Posaconazole: 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
Larotrectinib is cleared mainly by CYP3A4, so posaconazole can substantially increase its exposure. This raises the risk of dose-related adverse effects such as neurotoxicity, hepatotoxicity and myelosuppression.
What this interaction means in plain words
Larotrectinib and Posaconazole 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.
Larotrectinib belongs to Oncology; Posaconazole belongs to Anti Fungals.
Why it happens
Strong CYP3A4 inhibition by posaconazole decreases larotrectinib clearance.
What to do
Prefer an alternative antifungal. If unavoidable, reduce the larotrectinib dose by 50% and return to the previous dose after the inhibitor has been 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 Posaconazole
- Artemether + Posaconazole Contraindicated
- Avanafil + Posaconazole Contraindicated
- Cobimetinib + Posaconazole Contraindicated
- Conivaptan + Posaconazole Contraindicated
- Dihydroergotamine intranasal + Posaconazole Contraindicated
- Dihydroergotamine + Posaconazole Contraindicated
Other interactions of Larotrectinib
Frequently asked questions
Can I take Larotrectinib with Posaconazole?
MediHelp rates the interaction as major. Larotrectinib and Posaconazole 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. Larotrectinib is cleared mainly by CYP3A4, so posaconazole can substantially increase its exposure. This raises the risk of dose-related adverse effects such as neurotoxicity, hepatotoxicity and myelosuppression.
How serious is the interaction between Larotrectinib and Posaconazole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer an alternative antifungal. If unavoidable, reduce the larotrectinib dose by 50% and return to the previous dose after the inhibitor has been stopped for 3 to 5 half-lives.
What other medicines interact with Posaconazole?
MediHelp also lists interactions of Posaconazole with, for example, Artemether, Avanafil, Cobimetinib. The full list is on the Posaconazole page.
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