"We believe that ximelagatran holds promise as a new agent for the treatment of venous thromboembolism, a sometimes fatal disease that affects an estimated 250,000 to two million Americans a year," said Charles Francis, M.D., of the University of Rochester, Rochester, N.Y., presenting author of the study. "Further studies are needed to confirm its effectiveness over currently available treatments."
Researchers of this international, double-blind, double-dummy study (known as the Thrive Treatment Study) randomized 2,489 patients to either ximelagatran (36 mg twice a day) for six months (1,240 patients) or enoxaparin (1 mg/kg twice a day) for a minimum of five days followed by warfarin (target INR 2.0 to 3.0) for six months (1,249 patients). All participants, 53 percent of whom were men, had acute deep vein thrombosis and 37 percent had confirmed pulmonary embolism.
During six months of treatment, oral ximelagatran was as effective as enoxaparin/warfarin in preventing recurrent venous thromboembolism in patients with acute deep vein thrombosis, 2.1 percent versus 2.0 percent, respectively. Ximelagatran also was associated with a favorable outcome with respect to major bleeding (1.3 percent versus 2.2 percent) and mortality rates (2.3 percent versus 3.4 percent). Laboratory evaluation showed an incidence of serum alanine aminotransferase (ALAT, commonly measured to assess liver function) elevations of 9.6 percent, which is greater than three times the upper limit of normal, for patients receiving ximelagatran versus 2.0 percent for patients receiving enoxaparin/warfarin. These numbers are for patients who were in the intention-to-treat group.
Enoxaparin is used to prevent deep venous thrombosis, a condition in which harmful blood clots form in the blood vessels of the legs. It is often administered for several days after hip or knee replacement surgery, and is sometimes used to prevent blood clots from forming in the arteries of the heart during certain types of chest pain and heart attacks. Warfarin is used to prevent blood clots from forming or growing larger, and is often prescribed for patients with certain types of irregular heartbeat and after a heart attack or heart valve replacement surgery. It works by stopping the formation of substances that cause clots.
"Drugs such as enoxaparin and warfarin can be used successfully in patients with deep vein thrombosis; however, they require frequent monitoring and dose adjustments due to a narrow therapeutic window and interactions with other drugs," said Ronald Hoffman, M.D., President of the American Society of Hematology. "New drugs are needed to reduce the risk of patients experiencing venous thromboembolism while at the same time maintaining their quality of life without the interruptions that monitoring often incurs."
Thrombosis, or more specifically deep vein thrombosis (DVT), is a dangerous medical condition in which the formation of a blood clot blocks circulation in the deep veins of the lower limbs that are primarily responsible for returning deoxygenated blood to the heart. A number of factors contribute to one's chances of developing a clot, including age, genetics, infection or vascular injury, major surgery, inactivity, oral contraceptives, or hormone replacement therapy, particularly when combined with other risk factors like smoking, hypertension, or obesity. Blood clots can lead to potentially fatal events called pulmonary embolisms (PE), which occur when fragments of a blood clot break loose from the wall of the vein and migrate to the lungs, where they block a pulmonary artery or one of its branches.
The American Society of Hematology is the world's largest professional society concerned with the causes and treatment of blood disorders. Its mission is to further the understanding, diagnosis, treatment, and prevention of disorders affecting blood, bone marrow, and the immunologic, hemostatic, and vascular systems, by promoting research, clinical care, education, training, and advocacy in hematology.