eparina

Eparina, commonly referred to as heparin in many languages, is an anticoagulant medication used to prevent and treat blood clots. It is a heterogeneous, sulphated glycosaminoglycan produced from animal tissues and acts by enhancing the activity of antithrombin III, a natural inhibitor of coagulation factors.

Mechanism of action is based on its interaction with antithrombin III. The resulting complex inhibits thrombin (factor IIa) and factor Xa, with unfractionated heparin (UFH) affecting both IIa and Xa, while low-molecular-weight heparins (LMWH) preferentially inhibit Xa and have relatively less effect on IIa. This leads to reduced conversion of fibrinogen to fibrin and diminished clot formation. Because of its rapid onset, UFH is typically given by intravenous infusion or subcutaneous injection, while LMWH is usually administered subcutaneously and has a longer, more predictable effect.

Clinical uses include prophylaxis of thromboembolism after surgery, treatment of acute venous thromboembolism and pulmonary embolism, and management in acute coronary syndromes. It is also used in certain procedures and by patients undergoing dialysis or cardiopulmonary bypass. Because oral administration is ineffective for heparin, dosing and monitoring rely on laboratory tests and clinical assessment.

Monitoring and reversal are important. Unfractionated heparin requires regular monitoring of the aPTT to maintain therapeutic anticoagulation, whereas LMWHs often do not require routine monitoring. Protamine sulfate can rapidly reverse UFH and partially reverses LMWH effects.

Adverse effects include bleeding and heparin-induced thrombocytopenia (HIT), an immune-mediated complication that increases thrombotic risk. Caution is advised in pregnancy (LMWH often preferred) and in patients with active bleeding or significant spinal or epidural procedures.