Anti-platelet drug. Box and blister pack containing tablets of the anti-platelet drug clopidogrel, marketed under the name Plavix. Clopidogrel is used to prevent the formation of blood clots in patients with a history of heart attack, stroke, or peripheral vascular disease. It works by inhibiting adenosine diphosphate, a substance that induces blood platelet cells to aggregate and form blood clots. It can be used by patients unable to take aspirin.