Low molecular weight heparin has many advantages over unfractionated heparin

Antithrombotic therapy with intravenous unfractionated heparin has been the mainstay of early treatment of patients with venous thromboembolic disease and unstable angina. On a typical medical ward several patients will be attached to syringe drivers containing heparin. Management of these patients is time consuming: heparin infusions have to be made up daily, intravenous cannulas resited, blood samples analysed for monitoring of coagulation control, and doses adjusted on the basis of these results. The potential for dosing errors is high: even in trials with criteria for dose monitoring, over 60% of patients are overanticoagulated or underanticoagulated 24 hours after the start of heparin therapy.1 Newer low molecular weight heparins are much easier to administer, but do they have other advantages over unfractionated heparin?

The benefit of heparin treatment to patients with venous thromboembolic disease and unstable angina has been shown in several trials. In the only placebo controlled trial of heparin in pulmonary embolism the mortality rate was so much lower in treated patients that the trial was stopped.2 In unstable angina several randomised trials have indicated a trend towards reduced risk of death and non-fatal myocardial infarction in patients treated with aspirin …