Venous thromboembolism (VTE), a condition in which a blood vessel is blocked by a clot, is a common and potentially life-threatening disorder. In the United States, there are more than 200,000 new cases of VTE that occur annually. Treatment for acute VTE typically consists of an anticoagulant, such as a vitamin K inhibitor, for a period of six to 12 months.Following this, the decision to continue the treatment to prevent future clots is controversial. Long-term use of vitamin K inhibitors carries the risk of serious side effects, such as major bleeding, and requires regular laboratory monitoring to optimize the dose while reducing these risks. As an alternative, the safety and efficacy of rivaroxaban (Xarelto?, Bayer HealthCare/Bayer Schering Pharma), the first oral, direct Factor Xa inhibitor, anticoagulant that does not require continued monitoring and dose adjustment, was studied for long-term therapy and found to be safe and effective.EINSTEIN-Extension StudyEarly results from an extension trial investigating the effectiveness of rivaroxaban in the setting of secondary prevention showed the new factor Xa inhibitor is associated with a significant reduction in the risk of recurrent venous thromboembolism (VTE) events in patients who completed a course of anticoagulant therapy.In the trial, researchers enrolled 1,197 patients in a randomised, double-blind, placebo-controlled study involving 280 study sites in 28 countries. Prior to enrollment, the study participants had completed six to 12 months of anticoagulant treatment for acute VTE and were randomized to receive either 20 mg of rivaroxaban once daily (602 patients) or placebo (594 patients) for an additional six to 12 months.Treatment with rivaroxaban was found to be both safe and effective. Only eight patients (1.3%) on rivaroxaban showed signs of recurrent VTE events, compared with 42 patients (7.1 percent) in the placebo arm. In the rivaroxaban arm, four patients (0.7%) experienced major bleeding, though none of these events were fatal or at a critical site. Non-major bleeding, such as a nose bleed, skin hematoma (a swelling of blood), or blood in the urine, occurred in 32 patients (5.4%) taking rivaroxaban. In the placebo arm, there were no incidences of major bleeding, though seven patients (1.2%) experienced non-major bleeding. After the study medication was stopped, six symptomatic recurrent VTE events occurred in each group during a one-month observational period.?The results of this study are very compelling,? said lead study author Harry R. B?ller, MD, PhD, Professor of Medicine in the Department of Vascular Medicine at the University of Amsterdam Academic Medical Center in The Netherlands. ?For these patients in danger of having another VTE event, rivaroxaban lowered their risk by 82% without significantly increasing their risk of major bleeding. This once-daily pill provides the clinician with a simple option for patients in whom continued anticoagulant treatment is indicated.?Dr. B?ller will present the results of this study, Once-Daily Oral Rivaroxaban Versus Placebo in the Long-Term Prevention of Recurrent Symptomatic Venous Thromboembolism, the EINSTEIN-Extension Study (Abstract #LBA-2), in the Late-Breaking Abstracts Session during the 51st Annual Meeting of the American Society of Hematology, on Tuesday, December 8, at 7:30 a.m. in Hall F.For more information– Summary of Product Characteristics (SPC) as approved by the EMEA- Trial: Oral Direct Factor Xa Inhibitor Rivaroxaban in Patients With Acute Symptomatic Deep-Vein Thrombosis Without Symptomatic Pulmonary Embolism: Einstein-DVT Evaluation.- Trial: Oral Direct Factor Xa Inhibitor Rivaroxaban in Patients With Acute Symptomatic Pulmonary Embolism With Or Without Symptomatic Deep-Vein Thrombosis: Einstein-PE Evaluation.- Trial: Once-Daily Oral Direct Factor Xa Inhibitor Rivaroxaban in the Long-Term Prevention of Recurrent Symptomatic Venous Thromboembolism in Patients With Symptomatic Deep-Vein Thrombosis or Pulmonary Embolism. The Einstein-Extension Study.Also see these PubMed abstracts– Fassiadis N. Rivaroxaban, the first oral, direct factor Xa inhibitor. Expert Opin Pharmacother. 2009 Dec;10(18):2945-6.- Scheen AJ. Rivaroxaban (Xarelto): new anticoagulant inhibitor of factor Xa Rev Med Liege. 2009 Oct;64(10):538-43.- Laux V, Perzborn E, Heitmeier S, von Degenfeld G, et al. Direct inhibitors of coagulation proteins – the end of the heparin and low-molecular-weight heparin era for anticoagulant therapy? Thromb Haemost. 2009 Nov;102(5):892-9.

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