Antithrombotic agents LMWH

Fondaparinux, the factor Xa-binding pentasaccharide (Arixtra, MW 1,728 Da), is prepared synthetically, unlike UFH, LMWH and danaparoid, which are obtained from animal sources. Despite only inactivating free factor Xa, clinical trials indicate that fondaparinux is an effective antithrombotic agent, both for venous thromboembolism prophylaxis and treatment, as well as for acute coronary syndrome and ST elevation myocardial infarction [4]. 

Of the many drugs used as prophylactic antithrombotic agents, heparin has a long history as therapy for both DVT and pulmonary embolism (PE). Many studies have shown that in moderate and high risk patients, heparin can prevent postoperative DVT and PE (4,19-21). Now, with the introduction of LMWHs, these benefits can be had together with easier dosing and potentially less risk of bleeding. 

These agents interact directly with thrombin and do not require antithrombin to have antithrombotic activity. They are capable of inhibiting both circulating and clot-bound thrombin, which is a potential advantage over UFH and the LMWHs. They also do not induce immune-mediated thrombocytopenia and are widely used for the treatment of HIT. 

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