Atazanavir and Lapatinib interaction
Atazanavir 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 Lapatinib (TYKERB) label · effective 2026-01-27
If unavoidable, consider dose reduction of TYKERB in patients coadministered a strong CYP3A4 inhibitor.
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.
Effects of Lapatinib on Drug-Metabolizing Enzymes and Drug Transport Systems Lapatinib inhibits CYP3A4, CYP2C8, and P-glycoprotein (P-gp, ABCB1) in vitro at clinically relevant concentrations and is a weak inhibitor of CYP3A4 in vivo.
From the Atazanavir (REYATAZ) label · effective 2024-12-05
Direct-Acting Oral Anticoagulants: betrixaban, dabigatran, edoxaban ↑ betrixaban ↑ dabigatran ↑ edoxaban Concomitant use of REYATAZ with ritonavir, a strong CYP3A4/P-gp inhibitor, may result in an increased risk of bleeding.
Refer to the respective DOAC prescribing information regarding dosing instructions for coadministration with P-gp inhibitors. rivaroxaban REYATAZ with ritonavir ↑ rivaroxaban Coadministration of REYATAZ with ritonavir, a strong CYP3A4/P-gp inhibitor, and rivaroxaban is not recommended, as it may result in an increased risk of bleeding.
Close monitoring is recommended when REYATAZ is coadministered with rivaroxaban. apixaban REYATAZ with ritonavir ↑ apixaban Concomitant use of REYATAZ with ritonavir, a strong CYP3A4/P-gp inhibitor, may result in an increased risk of bleeding.
Refer to apixaban dosing instructions for coadministration with strong CYP3A4 and P-gp inhibitors in the apixaban prescribing information.
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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.