The following may be used: Aspirin 81 or 325 mg once a day Clopidogrel 75 mg once a day The combination product aspirin 25 mg / extended-release dipyridamole 200 mg 2 times a day In patients taking warfarin, antiplatelet drugs additively increase risk of bleeding and are thus usually avoided; however, aspirin is occasionally used simultaneously with warfarin in certain high-risk patients.