대한약국학회

This case report summarizes the patient case of a long-term warfarin user experiencing bleeding hemorrhoids and bleeding risk and drug interactions of warfarin, which was used as a teaching point during experiential rotation at a community pharmacy. The patient was regularly taking warfarin 0.5~5 mg per day for dilated cardiomyopathy since 2010. In 2019, at age 74, he was diagnosed with bleeding hemorrhoids and had to stop taking warfarin. While low risk of drug-drug interactions was found within the prescribed cardiomyopathy drug regimen, cross-prescription reviews confirmed a high risk of drug-drug interactions. The combination of loop diuretics and NSAIDS may cause nephrotoxicity (major), and the combination of anticoagulants and NSAIDS may increase the risk of bleeding (major). The patient was at high-risk for bleeding based on the HAS-BLED score ≥ 3.0 (old age, unstable INR, bleeding, drugs) and NSAID-induced bleeding risk factors ≥ 2 (old age, high-dose NSAIDS, combined use of anticoagulants). In order to minimize drug-drug interactions and optimize safety, following interventions are recommended: 1) modification of warfarin to a novel oral anticoagulant (NOAC) to reduce bleeding risk, 2) modification of NSAID to an agent with low risk of gastrointestinal bleeding or concurrent use of a gastrointestinal protective agent, 3) patient education on warfarin-induced bleeding risk and lifestyle habits to prevent bleeding. This case report is meaningful in confirming the importance of patient medication management in pharmacy practice by examining the bleeding risk and drug interactions of warfarin through 10-years follow-up of the drug history of patient with cardiomyopathy.