Idraparinux and idrabiotaparinux.

Idraparinux is a polymethylated synthetic pentasaccharide that binds to antithrombin with high affinity. Idrabiotaparinux is a derivative of idraparinux with biotin synthesized to the end-standing hexose. This article reports on data carried out with both compounds until April 2009. Idraparinux once weekly 2.5 mg subcutaneous was almost as effective for treatment of deep vein thrombosis but less effective for pulmonary embolism as initial bodyweight-adjusted subcutaneous enoxaparin followed by international normalized ratio-adjusted warfarin over 6 months for prophylaxis of recurrent venous thromboembolism (VTE). Prolonged prophylaxis of recurrent VTE with idraparinux was more effective but induced severe bleedings compared with placebo over an additional 6 months of prophylaxis of recurrent VTE. Prophylaxis of embolic events with idraparinux over an 18-month period in patients with atrial fibrillation was as effective as international normalized ratio-adjusted warfarin but induced more major bleeding complications. The elimination half-life of idraparinux increased to 60 days in these studies, which may explain the bleeding complications. As such the development of idraparinux was stopped. Idrabiotaparinux is eliminated after intravenous administration of avidin. Currently idrabiotaparinux once weekly 3.5 mg subcutaneous is being investigated in clinical trials for the prevention of recurrent events in patients with acute VTE and atrial fibrillation. The future of idrabiotaparinux depends on the demonstration of its safety and efficacy. Avidin also has to demonstrate its efficacy and safety after single and repeated injections.