Elevated International Normalized Ratio values in a patient receiving warfarin and ceftaroline.

Purpose: The case of a patient whose International Normalized Ratio (INR) became elevated due to a probable interaction between ceftaroline and warfarin is reported.

Summary: A 65-year-old African-American man developed an INR of >18.0 after completing 12 days of ceftaroline therapy for the treatment of cellulitis while taking warfarin therapy.