What is heparin (anticoagulant medication)?

From the Guidelines

Heparin is a widely used anticoagulant medication that prevents blood clots from forming or growing larger by inhibiting the clotting cascade, and it is recommended for use in patients with unstable angina or non-ST-elevation myocardial infarction, as well as for the prevention of deep vein thrombosis and pulmonary embolism 1.

Heparin Forms and Administration

Heparin comes in two main forms: unfractionated heparin (UFH), which is administered intravenously or subcutaneously in hospital settings, and low molecular weight heparin (LMWH) such as enoxaparin (Lovenox), which is typically given as subcutaneous injections.

• UFH requires frequent monitoring of activated partial thromboplastin time (aPTT) to ensure proper dosing, while LMWH generally doesn't require routine monitoring.
• The choice of heparin form and administration route depends on the patient's condition, the presence of renal impairment, and the risk of bleeding.

Mechanism of Action and Side Effects

Heparin works by binding to and enhancing the activity of antithrombin III, a natural protein that inactivates several clotting factors, particularly thrombin and factor Xa.

• The main side effect of heparin is bleeding, and in rare cases, it can cause heparin-induced thrombocytopenia (HIT), a serious condition where platelet counts drop and paradoxical clotting occurs.
• Protamine sulfate serves as an antidote for heparin overdose in emergency situations.

Clinical Use and Guidelines

Heparin is commonly used to treat or prevent conditions like deep vein thrombosis, pulmonary embolism, and during procedures like cardiac catheterization or dialysis.

• The American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines recommends the use of heparin in patients with unstable angina or non-ST-elevation myocardial infarction, as well as for the prevention of deep vein thrombosis and pulmonary embolism 1.

From the FDA Drug Label

Heparin is a heterogeneous group of straight-chain anionic mucopolysaccharides, called glycosaminoglycans, having anticoagulant properties. Heparin inhibits reactions that lead to the clotting of blood and the formation of fibrin clots both in vitro and in vivo.

Heparin is an anticoagulant medication that works by inhibiting the formation of blood clots. It is a complex mixture of sugars, including α-L-iduronic acid, 2-deoxy-2-sulfamino-α-D-glucose, and β-D-glucuronic acid, which are linked together to form polymers of varying sizes. Heparin acts by inhibiting the conversion of prothrombin to thrombin and preventing the formation of a stable fibrin clot. It is commonly used to prevent and treat thrombosis and embolism 2 2.

• Key points:
  • Heparin is an anticoagulant medication
  • It inhibits the formation of blood clots
  • It works by inhibiting the conversion of prothrombin to thrombin
  • It is a complex mixture of sugars
  • It is commonly used to prevent and treat thrombosis and embolism

From the Research

Definition and Mechanism of Heparin

• Heparin is an anticoagulant medication that is used to prevent and treat blood clots [ 3 , 4 ].
• It works by binding to antithrombin III, a plasma protein, to form a complex that inhibits the coagulation cascade [ 4 ].

Types of Heparin

• There are two main types of heparin: unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) [ 3 , 5 , 4 ].
• UFH is a mixture of mucopolysaccharide chains of various lengths, while LMWH has a lower molecular weight and a more predictable anticoagulant response [ 4 ].

Clinical Applications of Heparin

• Heparin is used to prevent and treat venous thromboembolism, pulmonary embolism, and atrial fibrillation [ 3 , 5 , 6 , 7 ].
• It is also used in the management of coronary artery disease and during cardiopulmonary bypass and extracorporeal membrane oxygenation [ 7 ].

Administration and Monitoring of Heparin

• Heparin can be administered intravenously or subcutaneously, and its effects are monitored using activated partial thromboplastin time (APTT) or anti-factor Xa levels [ 4 , 6 ].
• The optimal dosing regimens for heparin are still debated, and the risk of bleeding complications must be carefully balanced against the risk of thrombotic events [ 7 ].