Antithrombotic

Antithrombotic is an umbrella term for medicines that reduce blood clot formation or promote clot breakdown. These agents are used to prevent or treat thrombosis in arterial or venous circuits and may act by interfering with coagulation pathways, inhibiting platelets, or dissolving clots.

Anticoagulants inhibit the coagulation cascade to reduce thrombin generation and fibrin formation. Common types include unfractionated heparin and low‑molecular‑weight heparins, which enhance antithrombin activity; vitamin K antagonists such as warfarin; and direct oral anticoagulants that target specific factors (for example, dabigatran inhibits thrombin, while apixaban, rivaroxaban, and edoxaban inhibit factor Xa). Monitoring requirements vary: INR is used with vitamin K antagonists; aPTT can be used for heparins; DOACs generally require routine monitoring to assess renal function and potential interactions. Reversal agents exist for emergent bleeding or overdose (for example, protamine for heparin, vitamin K for warfarin, specific antidotes for DOACs in certain settings).

Antiplatelet agents hinder platelet activation or aggregation, addressing arterial thrombotic risk. Aspirin inhibits cyclooxygenase to reduce platelet production of thromboxane A2. P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor) prevent platelet activation through the ADP receptor, and glycoprotein IIb/IIIa inhibitors are used in acute settings. These drugs are commonly employed after myocardial infarction, in acute coronary syndromes, or around stent placement, with bleeding as the principal adverse effect.

Thrombolytics or fibrinolytics activate plasmin to dissolve clots and are used in specific acute settings such as ischemic stroke, ST-elevation myocardial infarction, and massive pulmonary embolism, where rapid clot breakdown outweighs bleeding risk.

Clinical use requires balancing thrombotic risk against bleeding risk, with consideration of patient factors, indications, and available reversal strategies.