Erlotinib and Ketoconazole interaction
Erlotinib and Ketoconazole: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Erlotinib label · effective 2024-06-26
Avoid co-administering erlotinib with strong CYP3A4 inhibitors (e.g., boceprevir, clarithromycin, conivaptan, indinavir, itraconazole, ketoconazole, lopinavir/ritonavir, nefazodone, nelfinavir, posaconazole, ritonavir, saquinavir, telithromycin, voriconazole, grapefruit or grapefruit juice) or a combined CYP3A4 and CYP1A2 inhibitor (e.g., ciprofloxacin).
Reduce the erlotinib dosage when co-administering with a strong CYP3A4 inhibitor or a combined CYP3A4 and CYP1A2 inhibitor if co-administration is unavoidable [see Dosage and Administration (2.4) ].
CYP3A4 Inhibitors Co-administration of erlotinib with a strong CYP3A4 inhibitor or a combined CYP3A4 and CYP1A2 inhibitor increased erlotinib exposure.
• CYP3A4 inhibitors or a combined CYP3A4 and CYP1A2 inhibitor increase erlotinib plasma concentrations.
From the Ketoconazole label · effective 2026-07-07
…specifically, should not be used within at least 72 hours of treatment with ketoconazole Antineoplastics irinotecan dasatinib, lapatinib, nilotinib bortezomib, busulphan, docetaxel, erlotinib, imatinib, ixabepilone, paclitaxel, trimetrexate, vinca alkaloids Irinotecan: The potential increase in plasma concentrations of irinotecan when coadministered with ketoconazole…
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.