Antiplatelet drugs

Antiplatelet drugs are drugs which treat and prevent thrombosis by targeting the platelet's role in the coagulation cascade, thereby reducing the blood's tendency to form thrombi.

Antiplatelets are mostly used to prevent thrombosis in the arterial circulation, including the coronary circulation.

As with anticoagulants, antiplatelets are also widely used in medicine (mostly cardiology and vascular surgery). Many patients are on antiplatelets. Unlike anticoagulants, antiplatelet drugs can be combined.

When there is vascular damage, receptors on the surface of platelets will bind to the subendothelial collagen with the help of von Willebrand factor. This causes the platelets to change shape and release their granules, which contain thromboxane A2, ADP and serotonin.

The molecules that were released from the granules bind to receptors on other platelets and activate them too. ADP will bind to P2Y12 receptor (and the P2Y1 receptor). During platelet aggregation, the glycoprotein IIb/IIIa receptor on the platelet surface binds to fibrinogen. This aggregates the platelets by sticking them together.

By interfering with the platelet’s function in haemostasis one can also inhibit thrombosis. Different drugs act on different aspects of platelet activation and aggregation.

Types

• Acetylsalicylic acid
• P2Y₁₂ inhibitors
• Dipyridamole
• Glycoprotein IIb/IIIa inhibitors

Indications

Antiplatelets are mostly used to prevent arterial thrombosis, and in higher doses, treat them:

• Acute myocardial infarction (treatment and prophylaxis)
• Ischaemic stroke (prophylaxis)
• After percutaneous coronary intervention (to prevent thrombosis of the stent)
• Peripheral artery disease

As you can see, antiplatelets are mostly used in case of arterial thrombosis due to atherosclerotic cardiovascular disease.