New Blood Thinner May Help Fight Dangerous Leg Clots
SATURDAY, Dec. 4 -- A new anti-clotting pill, rivaroxaban (Xarelto), may be an effective, convenient and safer treatment for patients coping with deep-vein thrombosis (DVT), a pair of new studies indicate.
According to the research, published online Dec. 4 in the New England Journal of Medicine, the drug could offer a new option for these potentially life-threatening clots, which most typically form in the lower leg or thigh.
The findings are also slated for presentation Saturday at the annual meeting of the American Society of Hematology (ASH), in Orlando, Fla.
"These study outcomes may possibly change the way that patients with DVT are treated," study author Dr. Harry R. Buller, a professor of medicine at the Academic Medical Center at the University of Amsterdam, said in an ASH news release. "This new treatment regimen of oral rivaroxaban can potentially make blood clot therapy easier than the current standard treatment for both the patient and the physician, with a single-drug and simple fixed-dose approach."
Another heart expert agreed.
"Rivaroxiban is at least as effective as the older drug [warfarin] and seems safer. It is also far easier to use since it does not require blood testing to adjust the dose," said cardiologist Dr. Alan Kadish, currently president of Touro College in New York City.
The study was funded in part by Bayer Schering Pharma, which markets rivaroxaban outside the United States. Funding also came from Ortho-McNeil, which will market the drug in the United States should it gain U.S. Food and Drug Administration approval. In March 2009, an FDA advisory panel recommended the drug be approved, but agency review is ongoing pending further study.
The authors note that upwards of 2 million Americans experience a DVT each year. These leg clots -- sometimes called "economy flight syndrome" since they've been associated with the immobilization of long flights -- can migrate to the lungs to form potentially deadly pulmonary embolisms.
The current standard of care typically involves treatment with relatively well-known anti-coagulant medications, such as the oral medication warfarin (Coumadin) and/or the injected medication heparin.
While effective, in some patients these drugs can prompt unstable responses, as well as problematic interactions with other medications. For warfarin in particular, the potential also exists for the development of severe and life-threatening bleeding. Use of these drugs, therefore, requires intense and continuous monitoring.
The search for a safer and easier to administer treatment option led Buller's team to analyze two sets of data: One that pitted rivaroxaban against the standard anti-clotting drug enoxaparin (a heparin-type medication), and the second which compared rivaroxaban with a placebo.
In the first instance, about 1,700 DVT patients were given rivaroxaban, while a similar number received enoxaparin, for a period of up to a year. In the second investigation, about 600 DVT patients who had completed at least six months of the first trial (on either medication) were randomly chosen to take rivaroxaban, while a similar number of patients were given a placebo.
The authors observed that fewer cases of clotting took place among the rivaroxaban group compared with those taking enoxaparin (2.1 percent vs. 3 percent, respectively). Major bleeding was also slightly less common among the former than the latter.
The new medication also significantly outperformed the placebo, with just over 1 percent of rivaroxaban patients experiencing clotting problems compared with more than 7 percent in the placebo group.
Although bleeding issues were more prevalent among rivaroxaban patients than among those taking a placebo, the research team determined that the new treatment option is both safe and effective for the treatment of DVT.
Dr. Murray A. Mittleman, director of the Cardiovascular Epidemiology Research Unit at Beth Israel Deaconess Medical Center at Harvard Medical School in Boston, said finding alternate treatments for DVT could be an "important advancement," even though rivaroxaban is likely to be a more expensive option.
"The problem with current treatments is not cost," he noted, "in the sense that warfarin, for example, has been around for a very long time and is very cheap. It's more a question of the considerable complications that come with current treatments, which means they require sometimes cumbersome and frequent monitoring, as well as dosage adjustments."
Kadish agreed. "While the cost of rivaroxiban is significant, the absence of monitoring costs, reduced time away from work [since blood test are not required] and the lower bleeding rate all serve to mitigate the cost differential relative to warfarin," he said.
"Also, DVT affects a broad age range of patients," Mittleman noted. "And that means that the risk for bleeding with current treatments can impact the lifestyles of young active people who are often advised to avoid activities that might prompt complications. So, it's a quality-of-life issue as well. So absolutely, a new, good treatment that would be safer and at least as effective would be very useful."
There's more on DVTs at the U.S. National Heart, Lung, and Blood Institute.
Posted: December 2010
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