There are two published case reports of increased INR in patients receiving warfarin who self-medicated with glucosamine-chondroitin supplements. Since chondroitin is a component of danaparoid, an anticoagulant that works by inhibiting activated factor X, it might have an anticoagulant effect and could increase the risk of bleeding in patients who are already receiving anticoagulants. Caution is advised for anyone taking chondroitin with warfarin or other anticoagulants or antiplatelet agents. Monitoring for bleeding episodes/changes in coagulation parameters when adding chondroitin to an anticoagulant or antiplatelet, or changing the dose of chondroitin is recommended. Chondroitin is often given in combination with glucosamine; readers are therefore advised to refer also to the UKMi Q&A on glucosamine drug interactions.
Senior Information Pharmacist, Welsh Medicines Information Centre