11.1 : 抗凝药物：低分子肝素

Hemostasis is a vital process that stops the bleeding from an injured blood vessel.

It involves an enzyme-catalyzed cascade called blood coagulation, which leads to stable blood clot formation.

When a clot blocks blood flow in vessels, it is called thrombosis.

Thrombotic diseases, such as myocardial infarction, stroke, and deep vein thrombosis, can be life-threatening.

Such conditions are treated by anticoagulants like unfractionated heparin or UFH.

UFH binds the endogenous anticoagulant, antithrombin, and enhances its inhibition of coagulation proteases to prevent blood clotting.

UFH is usually administered intravenously for rapid onset of action but needs close monitoring due to its variable pharmacokinetics.

Low-molecular-weight heparins or LMWHs, like enoxaparin and dalteparin, are smaller fragments of UFH that have the same efficacy as UFH.

 LMWHs are given subcutaneously and have greater bioavailability than UFH. Monitoring is not mandatory for LMWHs, making them the preferred choice for anticoagulation therapy.