[State of the art: low-molecular-weight heparin and beyond]

Approximately 20 years ago a new family of antithrombotic compounds started to be investigated: the low-molecular weight heparins (LMWH). The rationale for their use was based on the evidence that the inhibition of the Factor Xa of blood coagulation was less marked than that of Factor IIa when using the LMWHs as compared to unfractioned heparin (HF). This particular mechanism of action was considered to be of advantage regarding the safety profile (the pro-haemorrhagic effect) compared to HF. Today we know that the real advantage of LMWHs is due to their high bioavailability which makes safe and reliable their subcutaneous administration without laboratory monitoring. The LMWHs are equally effective than HF for the treatment of acute Deep Vein Thrombosis. For the prophylaxis of Venous Thromboembolism, LMWHs are indicated as first choice in high-risk patients such as those undergoing major orthopaedic surgery. The future development of this family of drugs encompasses the launch of the pentasaccharide which is a pure anti-/Xa inhibitor.