Information about Fondaparinux
Fondaparinux is a synthetic inhibitor of factor Xa which given by injection and is used as an anticoagulant to treat as well as prevent venous thromboembolism.
Liver safety of Fondaparinux
Fondaparinux has been associated with a low rate of serum aminotransferase elevations during therapy, but has not been implicated in cases of clinically apparent, idiosyncratic liver injury.
Mechanism of action of Fondaparinux
Fondaparinux (fon" da par' in ux) is a synthetic inhibitor of factor Xa which blocks the activity of this clotting factor indirectly by binding to and activating antithrombin III. Fondaparinux is composed of five monomeric sugars that are identical to the sequence present in heparin that comprises the high affinity binding site for antithrombin III. Unlike standard and low molecular weight heparins, however, fondaparinux is specific for factor Xa and has no effect on thrombin or other clotting factors. As a result, fondaparinux has a more predictable and reproducible anticoagulant effect and can be administered in a fixed dose once daily and does not require monitoring for anticoagulant effect.
FDA approval information for Fondaparinux
Fondaparinux was approved for use in the United States in 2001 and current indications include prevention of deep vein thromboses in high risk individuals (such as after surgery or during immobilization) and active treatment of deep vein thrombosis with or without pulmonary embolism (in combination with warfarin). Fondaparinux is available as solution for injection in prefilled syringes generically and under the brand name Arixtra.
Dosage and administration for Fondaparinux
The typical dose for prophylaxis of deep vein thrombosis is 2.5 mg subcutaneously once daily for 5 to 30 days. The dose regimen for treatment of deep vein thrombosis and pulmonary embolism is 5 to 10 mg (based upon body weight) subcutaneously once daily for at least 5 days and until a stable INR is achieved with warfarin. Side effects include bleeding and thrombocytopenia, but are less common than with heparin.
Side effects of Fondaparinux
Noncoagulation related side effects are uncommon but can include anemia, hypokalemia, insomnia, confusion, dizziness, hypotension, rash and purpura.