Plavix causes sticking of platelets to the damaged vessel wall and it aggregates to form a platelet plug. The platelet plug releases ADP and thrombaxane A2. In veins due to the sluggish blood flow a fibrinous tail is formed that traps RBCs and in arteries the thrombus is due to platelet plug. Plavix alters the receptors on platelets and inhibits ADP and fibrinogen induced platelet aggregation. The purinergic receptors which mediate adenylyl cyclase inhibition by ADP are blocked by Plavix. This prevents activation of platelets. Plavix also prevents fibrinogen binding to platelets but does not affect TXA2.