Concomitant used of Clopidogrel with aspirin, other NSAIDs, heparin and warfarin should be undertaken with caution for the fear of causing increased bleeding. No clinically significant pharmacodynamic interactions were observed when Clopidogrel was co-administered with atenolol, nifedipine, digoxin or theophylline. The pharmacodynamic activity of Clopidogrel was also not significantly influenced by the co-administration of phenobarbital, cimetidine or estrogen.
Clopidogrel may interfere with the metabolism of phenytoin, tamoxifen, tolbutamide, warfarin, torsemide, fluvastatin and many non-steriodal anti-inflammatory agents, but there are no data with to predict the magnitude of these interactions. Caution should be used when any of these drugs is co-administered with Clopidogrel. In addition to the above specific interaction studies, patients entered into CAPRIE received a variety of concomitant medication including diuretics, beta-blocking agents, angiotensin converting enzyme inhibitors, calcium antagonist, cholesterol lowering agents, coronary vasodilators, antidiabetic agents, anti-epileptic agents and hormone replacement therapy without evidence of clinically significant adverse interactions.