Abstract
With the advent of novel direct thrombin inhibitors (dabigatran) or factor Xa inhibitors (rivaroxaban, apixaban, etc.), a need has emerged to critically evaluate the role of established indirect factor Xa inhibitors and thrombin inhibitors, low molecular weight heparins (LMWHs), and to redefine their position among the other anticoagulants. Given the rapid onset of action, a reliable effect, the possibility to be administered once or twice daily and lower treatment costs, LMWHs remain to be effective drugs in the prophylaxis of thrombotic complications during procedures involving weight-bearing joints.
For this indication, rivaroxaban and apixaban are more effective, but more costly, and so is dabigatran. In the treatment of phlebothrombosis and pulmonary embolism, LMWHs are still the drugs of first choice given the poorer availability of fondaparinux.
In treating acute coronary events such as STEMI and non-STEMI, another important indication, low molecular weight heparins, namely enoxaparin, remain the gold standard as well. For this indication, the pentasaccharide fondaparinux is an alternative.
The effect of direct thrombin inhibitors and factor Xa inhibitors is being tested. When low molecular weight heparins are compared with each other, differences in both pharmacokinetic and pharmacodynamic properties can be found.
Molecules with lower amounts of saccharide units appear to be more advantageous. A direct comparison of effect in various indications is unfortunately unavailable; however, for instance in acute coronary events, their effect can be compared to that of unfractionated heparin.
In this comparison, enoxaparin is more advantageous than unfractionated heparin; dalteparin and nadroparin are not inferior to unfractionated heparin. When looking at low molecular weight heparins in terms of documented effect and approved indications, then again the largest body of evidence on effect is available for enoxaparin.