(Science: chemical) heparin fractions with a molecular weight usually between 4000 and 6000 kd. These low-molecular–weight fractions are effective antithrombotic agents. Their administration reduces the risk of haemorrhage, they have a longer half-life, and their platelet interactions are reduced in comparison to unfractionated heparin. They also provide an effective prophylaxis against postoperative major pulmonary embolism.
Pharmacological action: anticoagulant, fibrinolytic agent.