Objective: To report a case of increased international normalized ratio (INR) in a patient receiving warfarin and celecoxib.
Case summary: A 73-year-old white woman with hypothyroidism and heart failure was admitted to the hospital with increased orthopnea, dyspnea on exertion, and hemoptysis. On laboratory evaluation, she was noted to have an increased INR. The only reported change in her medications was the addition of celecoxib approximately five weeks before admission. Her INR had previously been stable. After discontinuation of warfarin and celecoxib, fresh frozen plasma and vitamin K were administered to normalize INR. The patient was not rechallenged.
Discussion: Warfarin is an oral anticoagulant with numerous reports of drug interactions. It is possible that other drug therapies or disease states may have contributed to the elevation in INR; however, the observed increase in INR occurred five weeks after beginning celecoxib therapy. The Food and Drug Administration has issued a notice about the possibility of interactions between these two medications.
Conclusions: Celecoxib may potentiate the anticoagulant effects of warfarin. Patients receiving warfarin should be carefully monitored when adding, changing, or removing celecoxib from their medication regimen.