**11. Factor Xa inhibitors**

The synthetic pentasaccharide Fondaparinux is an indirect FXa inhibitor, with structural similarities to heparin. It works by facilitating antithrombin III (AT) activity, and is therefore dependent on AT for its effect (16). Fondaparinux is given subcutaneously for prevention/treatment of venous thromboembolism, and for acute coronary syndrome. In patients with normal renal function, anticoagulation effects persist for 2-4 days after discontinuation of Fondaparinux. There is no antidote available to reverse the effect of Fondaparinux. It does not affect PT, APTT or ACT. Although monitoring is not routinely required in healthy patients, it can be achieved by an anti-FXa assay.

Newer orally-administered drugs Rivaroxiban and Apixaban are direct FXa inhibitors. They have similar indications to Fondaparinux.
