Ketoconazole and Lapatinib interaction
Ketoconazole and Lapatinib: 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 Ketoconazole label · effective 2026-07-07
…Eletriptan should be used with caution with ketoconazole, and 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…
From the Lapatinib (TYKERB) label · effective 2026-01-27
If unavoidable, consider dose reduction of TYKERB in patients coadministered a strong CYP3A4 inhibitor.
TYKERB may prolong the QT interval in some patients.
Ketoconazole : In healthy subjects receiving ketoconazole, a CYP3A4 inhibitor, at 200 mg twice daily for 7 days, systemic exposure (AUC) to lapatinib was increased to approximately 3.6-fold of control and half-life increased to 1.7-fold of control.
Drugs That Inhibit or Induce Cytochrome P450 3A4 Enzymes Lapatinib undergoes extensive metabolism by CYP3A4, and concomitant administration of strong inhibitors or inducers of CYP3A4 alter lapatinib concentrations significantly (see Ketoconazole and Carbamazepine sections, below) .
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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.