Drug Interaction Between Gefitinib and Warfarin

Gefitinib is a synthetic, oral anilinoquinazoline specifically designed to inhibit the epidermal growth factor receptor tyrosine kinase, and is the first targeted drug to demonstrate reproducible activity in non-small cell lung cancer patients who do not respond to platinum-based chemotherapy. In this report, we present two cases of an interaction between gefitinib and warfarin which has not been reported previously. Because of the potentially serious consequences of this interaction, close monitoring of the International Normalized Ratio and warfarin dosage adjustment are recommended for patients receiving warfarin together with gefitinib.