III.Low molecular weight heparin (LMWH)

Nadroparin, enoxaparin, and tinzaparin have a shorter half-life compared to UFH. However, LMWH is not necessarily monitored unless in some conditions, such as pregnancy and renal failure [12].

## IV.Fondaparinux sodium

Fondaparinux sodium also called "Arixtra", is a new class of synthetic pentasaccharide anticoagulants that bind to ATIII and indirectly inhibit the action of factor Xa. It has a similar mode of action to LMWH but has a longer half-life (17–21 h) than heparin. It does not prevent thrombin generation or interact with platelets but could be an essential and effective alternative to LMWH for the treatment of VTE following an orthopaedic surgical procedure. Fondaparinux is administered subcutaneously and excreted by unsaturated renal filtration [1].
