Heparin-induced thrombocytopenia (HIT) is an immune-mediated complication that can occur after patients receive heparin products. HIT increases the risk of clot formation, so patients are treated with anticoagulants. Treatment with warfarin alone in the setting of acute HIT further increases clotting risk, so patients are typically treated with direct thrombin inhibitors such as lepirudin or argatroban. Bivalirudin, another direct thrombin inhibitor, is approved for use in patients who must undergo percutaneous coronary intervention.
Factor Xa inhibitors, such as danaparoid and fondaparinux, also inhibit thrombin production but do not have an FDA indication for treatment of HIT. Also, danaparoid is not available in the United States. Limited published information suggests that fondaparinux may be useful for the treatment of HIT. Case reports for approximately 30 patients with acute HIT or a history of HIT describe positive outcomes for patients who were treated with fondaparinux for periods up to 3 months. The combination of once-daily dosing, predictability of response, and minimal side effects makes fondaparinux an appealing alternative for patients with HIT; however, it is not currently recommended as first-line therapy.