What is the primary function of heparin sodium and its low molecular weight derivatives like enoxaparin?

The primary function of heparin sodium and its low molecular weight derivatives, such as enoxaparin, is to inhibit the formation of fibrin clots. These anticoagulants work by enhancing the activity of antithrombin III, a natural inhibitor of coagulation factors such as thrombin and factor Xa. By inhibiting these factors, heparin and its derivatives effectively prevent the conversion of fibrinogen to fibrin, which is essential for clot formation. This action helps to reduce the risk of thromboembolic events, making heparin a crucial medication for patients at risk for conditions like deep vein thrombosis and pulmonary embolism.

In contrast, increasing blood vessel diameter, reducing blood pressure, or enhancing white blood cell production are not functions associated with heparin or its derivatives. These actions are related to different physiological processes and medications, highlighting the specific role that heparin plays in anticoagulation therapy.