Antiplatelet drugs are used to prevent or reduce the risk of blood clots by decreasing platelet function and preventing thrombus formation in arteries. Common antiplatelet medications include aspirin and thienopyridines, each acting through different mechanisms to inhibit platelet activation. While effective for conditions like cardiovascular disease and arteriosclerosis, these drugs can cause side effects such as bleeding and bruising, and have specific contraindications that need to be considered.