Gefitinib and Warfarin

Gefitinib (brand name Iressa^®) is a drug used in certain types of cancer. Gefitinib is only indicated for the treatment of locally advanced or metastatic non-small cell lung cancer (NSCLC) in patients who have previously received chemotherapy.

An article appearing in the March 2005 Japanese Journal of Clinical Oncology called attention to the potential danger of interacting with warfarin. Since then, several additional clinical articles have indicated an interaction between gefitinib and warfarin. "Patients taking warfarin should have their International Normalized Ratio (INR) monitored, since INR elevations, as well as bleeding events, have been reported in patients taking both gefitinib and warfarin."¹

More frequent testing has been recommended for potentially dangerous interacting medications with warfarin. As always, consult with your doctor before starting or stopping medications.

1. Shah N, et al. Practical Management of Patients With Non–Small-Cell Lung Cancer Treated With Gefitinib. Journal of Clinical Oncology, Vol 23, No 1 (January 1), 2005: pp. 165-174.