Rationale for development of low-molecular-weight heparins and their clinical potential in the prevention of postoperative venous thrombosis

Interest in low-molecular-weight heparins (LMWHs) as potential antithrombotic agents was stimulated by two observations in the mid-1970s and early 1980s. The first was finding that LMWH fractions prepared from unfractionated heparin (UFH) progressively lost their ability to prolong the activated partial thromboplastin time (APTT) while retaining their ability to inhibit Factor Xa. The second was the observation that LMWHs prepared by chemical …