- Concomitant use of aspirin (> 150 mg/day), non-steroidal anti-inflammatory drugs (except specific COX-2 inhibitors), heparin, low molecular weight heparin, warfarin (> 1 mg/day) or anti-platelet drugs (abciximab, clopidogrel, dipyridamole, ticlopidine and tirofiban). Low-dose aspirin (≤ 150 mg/day) and low-dose warfarin (≤ 1 mg/day) are permitted as concomitant medications.