Low molecular weight heparins

Low molecular weight heparins (LMWHs) have been prepared from unfractionated heparin by means of different fragmentation or fractional procedures with the aim of obtaining a more effective and/or safer antithrombotic agent than standard heparin (SH). LMWHs resulting from different production procedures are structurally heterogeneous; this could account for the different efficacy and safety observed clinically. Many clinical trials have been carried out on the prevention of deep-vein thrombosis (DVT) and pulmonary embolism in patients undergoing major abdominal or orthopedic surgery, hemodialysis or affected by non-hemorrhagic stroke. Moreover, experience is accumulating on the use of LMWHs in the treatment of DVT. LMWHs have been shown to be an effective antithrombotic agent in preventing DVT in general surgery when compared to placebo. Furthermore, CY 216, given once daily, is at least as effective as standard heparin given twice or three times daily. In two studies CY 216 was more effective than standard heparin. However, the promising experimental findings that LMWHs produce less bleeding than standard heparin have not been proved yet. There is convincing evidence that PK 10169 is effective in preventing DVT in patients undergoing hip surgery. In one study PK 10169 was more effective than standard heparin. Both ORG 10172 and KABI 2165 were effective in the prevention of DVT in patients with stroke but the safety in terms of bleeding remains to be established. The role of LMWHs in DVT treatment has yet to be established. The dose of LMWHs which offers the best risk-benefit ratio must be established for each compound before LMWHs are accepted as standard prophylaxis or treatment.(ABSTRACT TRUNCATED AT 250 WORDS)