Low-molecular-weight heparin for thromboprophylaxis (original) (raw)
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Low-Molecular-Weight Heparins for the Prevention and Treatment of Venous Thromboembolism
Military Medicine, 2001
Low-molecular-weight heparins (LMWHs) are rapidly becoming the anticoagulants of choice for the prevention and treatment of venous thromboembolism. LMWHs are at least as safe and effective as unfractionated heparin, and they have the added advantage of improved pharmacokinetic and safety profiles. The result is that LMWHs are easier to use, provide a more predictable anticoagulant effect, and do not require routine laboratory monitoring in most circumstances. Currently, the LMWHs ardeparin, dalteparin, danaparoid, enoxaparin, and tinzaparin have Food and Drug Administration-approved indications in the United States. This paper reviews the clinical use and cost-effectiveness of the LMWHs for the prevention and treatment of venous thromboembolism.
Current Opinion in Pulmonary Medicine, 1998
Inn this review, we analyzed data from randomized trials in which low molecular weight heparinn was compared with untractionated heparin, both to estimate the treatment effectt of low molecular weight heparin in the initial treatment of \enous thromboembolismm and to evaluate the effect of varied proportion of cancer patients (6°-' oo to 22"(i) on the incidence of outcome events (recurrence of venous thromboembolism,, bleeding and mortality) and on the estimated treatment effect.
Unfractionated versus low-molecular-weight heparin in the treatment of venous thromboembolism
Low-molecular-weight heparin (LMWH) fractions are prepared from standard unfrac-tionated heparin (UFH) and are thus similar to UFH in many aspects. The main advantages of this new class of antithrombotic agents as compared with UFH are: (1) an improved bioavail-ability and a prolonged half-life, which alleviate cumbersome laboratory monitoring and may permit one single daily subcutaneous injection; and (2) an improved efficacy-to-safety ratio, with less bleeding despite similar or improved efficacy. For these reasons, LMWH is progressively replacing UFH for preventing postoperative thromboembolism and for treating established deep vein thrombosis and pulmonary embolism. However, the effects of the new compounds need to be evaluated carefully in some other indications (arterial thrombosis, unstable angina, or myocardial infarction – the latter also in conjunction with thrombolytic treatment) before they can generally replace UFH in pharmacotherapy.
Annals of Hematology, 2007
The objective was to assess the use of suboptimal doses (60–149 UI kg−1 day−1) of low molecular weight heparin (LMWH) in the treatment of acute venous thromboembolism (VTE) in actual clinical practice and to evaluate the outcomes compared to standard doses (≥150 UI kg−1 day−1). Retrospective analysis of data from a multicenter registry of patients with VTE (RIETE; Registro Informatizado de Enfermedad TromboEmbólica). Patient characteristics, antithrombotic treatments, and 3-month outcomes were analyzed. We studied 12,302 patients with VTE; 10,524 patients were treated initially only with LMWH; 1,547 patients received suboptimal LMWH (mean = 122 UI kg−1 day−1), and 8,977 patients received full-dose LMWH (mean = 191 UI kg−1 day−1). The suboptimal group included significantly more patients with recent major bleeding, weight more than 100 kg, raised creatinine, or deep vein thrombosis. No significant differences in mortality rate (7.7 vs 7.8%), VTE recurrence (2.7 vs 2.3%), or fatal hemorrhage (0.6 vs 0.6%) occurred between the suboptimal and the standard group. Major bleeding episodes occurred more frequently in the patients with pulmonary embolism treated with suboptimal LMWH (4.5 vs 2.4%; p = 0.02). In the multivariate analysis, after adjusting for bleeding risk factors, major hemorrhage was not associated with the heparin dose. Suboptimal doses of LMWH are used in actual clinical practice in a reduced group of patients at an outcome rate not very different to that of standard doses. Bleeding episodes depend more on the patient’s characteristics than on the LMWH dose. Randomized trials should be performed to corroborate these results.
Secondary Prevention of Venous Thromboembolism: A Role for Low-Molecular-Weight Heparin
Pathophysiology of Haemostasis and Thrombosis, 1998
Background: After a short initial course of heparin therapy, patients with venous thrombo-embolism (VTE) require continuing anticoagulant therapy for several months after hospital discharge. At present, two small-scale studies have compared the efficacy and safety of low-molecular-weight heparin (LMWH) with warfarin in the secondary prevention of VTE. Patients and Methods: We studied 654 consecutive patients, 202 with pulmonary embolism (PE) and 452 patients with deep vein thrombosis (DVT) of the lower limbs. 220/ 654 patients (34%) were considered to have some contraindications to coumarin, and
Circulation, 1989
We performed a prospective, randomized, double-blind trial in 194 unselected patients to determine the safety and efficacy of low molecular weight heparin (Fragmin) compared with standard heparin as the initial treatment of acute venous thromboembolism. Ninety-eight patients received continuous intravenous heparin, and 96 patients received Fragmin for 5-10 days. Doses were adjusted to maintain anti-Xa levels between 0.3 and 0.6 unit/ml for patients with a high risk for a bleeding complication and between 0.4 and 0.9 unit/ml for patients with a low risk for bleeding. Treatment was stopped when a therapeutic level of anticoagulation (International Normalized Ratio >3.5) was reached with coumarins. Thirteen patients in the heparin group and 10 patients in the Fragmin group had a major bleeding complication. The incidence of major and minor bleeding complications combined decreased from 48.9% to 38.5% (95% confidence interval for the dilference,-3.5% to +24.2%), corresponding with a relative bleeding risk reduction of 21.2%. There were no significant differences in efficacy as defined by new high-probability defects on repeat ventilation-perfusion scintigraphy of the lung in 80 patients: six of 46 patients in the heparin group and 3 of 34 patients in the Fragmin group had new defects (95% confidence interval for the difference,-9.4% to + 17.8%). We conclude that low molecular weight heparin (Fragmin) given in adjusted, continuous, and intravenous doses is safe and effective as initial treatment of acute venous thromboembolism compared with heparin. There is a trend in risk reduction for bleeding in favor of low molecular weight heparin, a trend, however, that is smaller than expected compared with animal studies. (Circulation 1989;80:935-940) H eparin is used in relatively large doses in the management of thromboembolic disease with the aim of preventing extension and embolization of venous thrombi. The treatment, however, is associated with an appreciable risk of hemorrhage. This has prompted research to improve the benefit to risk ratio of the drug. Heparin acts as an anticoagulant by accelerating the complex formation between antithrombin III and various activated clotting factors, among which factor Xa and thrombin are the most important. Fractionation of the polydisperse heparin according to molecular size has led to the development of low molecular weight heparin preparations with an increased anti-Xa to antithrombin ratio.1 These low molecular weight heparins have been shown to
Use of heparin for the prevention of venous thromboembolism
Pharmacoepidemiology & Drug Safety, 1994
The value of heparin in the prevention of venous thromboembolism has been shown effective and safe by controlled studies. However, how these studies have influenced physicians' decisions in thromboprophylaxis is not known. With the aim of evaluating the frequency and the appropriateness of prophylaxis for venous thromboembolism in our centre, we performed a cross-sectional study on a specific day. Among 667 patients who were admitted to hospital on this day, 134 (20 per cent) were receiving heparin. This had been prescribed for the prophylaxis of venous thromboembolism to 82 (12 per cent) patients. Immobilization was the risk factor most strongly associated with prophylaxis. Prophylaxis with heparin was only used in 79 out of 444 high-risk patients (21.6 per cent). One hundred and eighty-three patients had been subject to major surgery and heparin was being given only to 34 of them (18.6 per cent). A wide variability in the use of prophylaxis, depending on the hospital ward, was also recorded. We conclude that prophylaxis with heparin is underused in our milieu.