Subcutaneous unfractionated heparin for the treatment of venous thromboembolism

When unfractionated heparin is used to treat acute venous thromboembolism, it is usually given by intravenous infusion with dose adjustment in response to activated partial thromboplastin time measurements. These two requirements are a barrier to treatment of venous thromboembolism with unfractionated heparin, and it is uncertain if they are necessary.

Two recent studies compared subcutaneous unfractionated heparin and subcutaneous low-molecular-weight heparin, each given twice-daily, for the acute treatment of venous thromboembolism. The Galilei study used an initial dose of unfractionated heparin that was partially weight-adjusted, with subsequent dosing based on activated partial thromboplastin time results. The FIDO study treated patients with a first dose of unfractionated heparin of 333 IU/kg, followed by 250 IU/kg twice-daily without dose adjustment in response to the activated partial thromboplastin time or other coagulation tests. There was no difference in either study between the unfractionated heparin and low-molecular-weight heparin groups at the end of 3 months, for recurrent venous thromboembolism (Galilei: 4.2 vs. 3.9%; relative risk (RR) 1.1, 95% confidence interval (CI) 0.5 to 2.2. FIDO: 3.8 vs. 3.4%; RR 1.1, 95% CI 0.5 to 2.3) or major bleeding (Galilei: 1.4 vs. 1.9%; RR 0.7, 95% CI 0.2 to 2.2. FIDO: 1.7 vs. 3.4%; RR 0.5, 95% CI 0.2 to 1.3).

Recent studies suggest that twice-daily subcutaneous unfractionated heparin is as effective and safe as low-molecular-weight heparin for the acute treatment of venous thromboembolism, and that adjustment of unfractionated heparin dose in response to activated partial thromboplastin time measurements is not necessary with a weight-adjusted dose of unfractionated heparin.