What Is Fractionated Heparin?

Fractionated heparin is a product of the breakdown of unfractionated heparin. It is also known as low-molecular-weight heparin (LMWH). LMWH is an anticoagulant used for the prevention and treatment of thromboembolic disorders, which are characterized by the formation of blood clots (thrombus). LMWH has many advantages over unfractionated heparin.

Uses

LMWH is used in the treatment of acute coronary syndromes, deep vein thrombosis and pulmonary embolism, as well as in the prevention of venous thromboembolism in high-risk populations.

Administration

LMWH is available as a solution, in varying concentrations, in both prefilled syringes and multiple-dose vials. It is given in fixed or weight-based doses, most often once daily, by subcutaneous injection. LMWH is suitable for acute or long-term use, and it is appropriate for both inpatient and outpatient administration.

Mechanism of action

LMWH produces its anticoagulant effect by binding to antithrombin and inhibiting the activity of blood coagulation factors. Primarily, LMWH inactivates factor Xa.

Adverse Effects

Bleeding is the most common adverse effect associated with LMWH. The incidence of bleeding, however, is less than 5% for most LMWH products. Due to the low risk of bleeding and the predictable anticoagulant effects of LMWH, routine laboratory monitoring is not necessary. Signs or symptoms of bleeding should be reported to a healthcare provider immediately.

Related Compounds

LMWH is a smaller compound than unfractionated heparin. LMWH has a longer duration of action, produces a more predictable anticoagulant response in patients, and is less likely to cause serious adverse reactions compared with unfractionated heparin.

Product Comparison

Several LMWH products are available, including dalteparin, nadroparin, enoxaparin and tinzaparin. LMWH products are manufactured using different processes for breaking apart unfractionated heparin, yielding final products that differ in size and in chemical and physical properties. All LMWH products are similar in their mechanism of action, safety and effectiveness.

References

• "Pharmacotherapy: A Pathophysiologic Approach," 5th ed; J. P. DiPiro, et. al., eds; 2002
• "Drug Information Handbook," 11th ed; C. F. Lacy, et. al.; 2003
• "Chest" journal; Heparin and Low-Molecular-Weight Heparin: Mechanisms of Action, Pharmacokinetics, Dosing, Monitoring, Efficacy, and Safety; J. Hirsh, et. al.; January 2001

Resources

• University of Michigan Health System: Low Molecular Weight Heparin (LMWH)
• Institute for Healthcare Improvement: Use Low Molecular Weight Heparin (LMWH)