Of the following therapeutic agents, those considered to be antiplatelet medications are:

• A. Aspirin and Plavix
• B. Coumadin and heparin
• C. Heparin and protamine sulfate
• D. Tissue plasminogen activator and streptokinase

Answer: (A)

Antiplatelet therapy targets the initial step of clot formation by preventing platelets from sticking together. Aspirin blocks COX-1 in platelets, lowering thromboxane A2 and thus reducing platelet aggregation. Plavix (clopidogrel) blocks the P2Y12 receptor on platelets, which prevents ADP-mediated platelet activation and further aggregation. Together, they are classic antiplatelet agents used to prevent arterial clots that can cause heart attack or stroke.

The other combinations involve drugs that act on different parts of the clotting system. Anticoagulants like warfarin (Coumadin) and heparin interfere with the coagulation cascade, not platelet function, and are used in conditions like venous thrombosis and atrial fibrillation. A pairing that includes heparin would still be anticoagulant therapy, not antiplatelet. Thrombolytics such as tissue plasminogen activator and streptokinase dissolve clots by breaking down fibrin, not by inhibiting platelets.