- Concomitant treatment, in therapeutic doses, with anticoagulants such as warfarin or warfarin-related agents, heparin, low molecular weight heparin (LMWH), thrombin or Factor Xa inhibitors, or antiplatelet agents (e.g., clopidogrel). (low dose aspirin [=< 81 mg/day] and prophylactic LMWH are permitted)