Antiplatelet Therapy

Antiplatelet therapy refers to the use of medications that prevent platelets in the blood from clumping together and forming blood clots. This type of therapy is commonly used to prevent strokes, heart attacks, and other cardiovascular events.

Purpose

The primary purpose of antiplatelet therapy is to reduce the risk of thrombotic events, such as:

• Myocardial infarction (heart attack)
• Stroke
• Transient ischemic attack (TIA or "mini-stroke")
• Peripheral artery disease

How it Works

Antiplatelet medications work by inhibiting the activation of platelets, which are small cells in the blood that play a crucial role in blood clotting. When platelets become activated, they release chemical signals that attract other platelets and form a platelet plug, which can lead to the formation of a blood clot.

Antiplatelet medications block one or more of the following pathways:

• Cyclooxygenase (COX) pathway: blocks the production of thromboxane A2, a chemical that activates platelets
• Phosphodiesterase (PDE) pathway: blocks the breakdown of cyclic adenosine monophosphate (cAMP), which inhibits platelet activation
• P2Y12 receptor pathway: blocks the binding of adenosine diphosphate (ADP) to its receptor, which activates platelets

Types of Antiplatelet Medications

Common antiplatelet medications include:

• Aspirin: inhibits COX pathway
• Clopidogrel (Plavix): inhibits P2Y12 receptor pathway
• Prasugrel (Effient): inhibits P2Y12 receptor pathway
• Ticagrelor (Brilinta): inhibits P2Y12 receptor pathway
• Ticlopidine (Ticlid): inhibits P2Y12 receptor pathway

Benefits and Risks

The benefits of antiplatelet therapy include:

• Reduced risk of myocardial infarction, stroke, and other cardiovascular events
• Improved outcomes in patients with acute coronary syndrome or stroke

The risks of antiplatelet therapy include:

• Bleeding complications, such as gastrointestinal bleeding or intracranial hemorrhage
• Increased risk of bruising and petechiae (small red or purple spots on the skin)

Contraindications and Precautions

Antiplatelet therapy is contraindicated in patients with:

• Active bleeding or bleeding disorders
• Pregnancy or breastfeeding (except for low-dose aspirin)
• Severe liver or kidney disease

Precautions should be taken when using antiplatelet medications in patients with:

• Bleeding tendencies or history of bleeding complications
• Gastrointestinal ulcers or other conditions that increase the risk of bleeding
• Renal impairment or hepatic dysfunction