Studies address low-molecular-weight heparin
As safe as infused, unfractionated heparin
A pair of studies published recently in the New England Journal of Medicine notes that fixed-dose subcutaneous low-molecular-weight heparin is as effective and safe as adjusted-dose intravenous unfractioned heparin in patients with pulmonary embolism or previous episodes of thromboembolism. The studies also show that fixed-dose subcutaneous low-molecular-weight heparin is effective in patients with acute pulmonary embolism.
In one study, 1,021 patients with symptomatic venous thromboembolism were assigned to fixed-dose subcutaneous low-molecular-weight heparin (reviparin sodium) or adjusted-dose intravenous unfractionated heparin to determine whether low-molecular-weight heparin is at least equivalent to unfractionated heparin in patients with venous thromboembolism.1 The above dosage was accompanied by oral anticoagulant therapy with a coumarin derivative and continued for 12 weeks.
The study found that 27 of the 510 patients assigned to low-molecular-weight heparin (5.3%) had recurrent thromboembolic events, compared with 25 of the 511 patients assigned to unfractionated heparin (4.9%). The researchers thus concluded that fixed-dose subcutaneous low-molecular-weight heparin is as effective and safe as adjusted-dose intravenous unfractionated heparin for initial management of venous thromboembolism, regardless of whether the patient has pulmonary embolism or a history of venous thromboembolism.
The second study2 compared low-molecular-weight heparin with unfractionated heparin for acute pulmonary embolism. The study randomly assigned 612 patients with symptomatic pulmonary embolism who did not require thrombolytic therapy or embolectomy to either subcutaneous low-molecular-weight heparin (tinzaparin) given once daily in a fixed dose or adjusted-dose intravenous unfractionated heparin. Patients received oral anticoagulant therapy between the first and third day and continued the therapy for at least three months. Treatments at day eight and day 90 were compared regarding a combined end point of recurrent thromboembolism, major bleeding, and death. Researchers concluded that under the conditions of the study, initial subcutaneous therapy with low-molecular-weight heparin tinzaparin appeared to be as effective and safe as intravenous unfractionated heparin in patients with acute pulmonary embolism.
References
1. Buller H, Gent M, Gallus A., et al. Low-molecular-weight heparin in the treatment of patients with venous thromboembolism. N Engl J Med 1997; 337:657-662.
2. Simonneau G, Sors H, Charbonnier B, et. al. A comparison of low-molecular-weight heparin with unfractionated heparin for acute pulmonary embolism. N Engl J Med 1997; 337:663-669.
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