Prolonged antithrombin activity of low-molecular-weight heparins. Clinical implications for the treatment of thromboembolic diseases.

BACKGROUND: The mechanism for the efficacy of once- or twice-daily subcutaneous injections of low-molecular-weight heparins (LMWHs) for the treatment of venous thromboembolism has been difficult to explain. The confusion exists because the observation from experimental studies that the antithrombin activity of LMWHs is necessary for their antithrombotic effect is inconsistent with the reported short half-life of the antithrombin activity of …