Study Pits New Blood Thinner Against Warfarin For
WEDNESDAY, Aug. 10 (HealthDay News) -- A new drug that lowers
stroke risk among people with an irregular heartbeat may give the
old standby, warfarin, some competition, a new study shows.
Individuals with an erratic heartbeat known as atrial
fibrillation are at increased risk for ischemic stroke, which is
caused by a blockage such as a blood clot. For this reason, they
have to take blood-thinning medications to lower this risk.
Warfarin (also known as Coumadin) is considered the gold standard
medication, but it often requires monitoring, adjustments and
stringent dietary restrictions.
The new trial pitted the newer drug, rivaroxaban (Xarelto),
against warfarin in more than 14,000 patients who were randomly
assigned either warfarin or rivaroxaban. Neither the patients nor
the doctors knew who was taking which drug.
The new agent proved to be as effective as warfarin at reducing
the risk of ischemic stroke -- the most common kind of stroke --
but it did not need to be monitored as closely as warfarin since it
is given as a one-size-fits-all dose.
Although potentially lifesaving, all blood-thinning drugs confer
a risk of potentially life-threatening bleeding. The two
medications had similar bleeding rates overall, but the new agent
was less likely to cause fatal bleeds or bleeding in the brain,
according to the study, which appears in the Aug. 11 issue of the
New England Journal of Medicine.
In contrast, bleeding in the gastrointestinal region occurred
more often in the rivaroxaban group, as did bleeds requiring
The study was funded by Johnson & Johnson Pharmaceutical
Research & Development and Bayer Healthcare, the makers of
The new drug is already approved to help prevent deep vein
thrombosis, or blood clots that form deep in a vein somewhere in
the body, usually the leg. Rivaroxaban is not the only new blood
thinning drug in the pipeline, however: Pradaxa (dabigatran
etexilate) recently got the FDA's nod for lowering stroke risk
among people with atrial fibrillation, and Eliquis (apixaban) is
also making its way down the drug development pike.
Study author Dr. Manesh R. Patel, an assistant professor of
medicine at Duke University School of Medicine in Durham, NC, said
that the new agent may be "a reasonable alternative to warfarin,
with less intracranial or fatal bleeding." Many people on warfarin
need to have their blood monitored to ensure that a blood clotting
test known as the International Normalized Ratio (INR) is where it
should be, and there are also many dietary restrictions, he
"You can't eat broccoli and other vitamin-K rich foods" on warfarin, Patel said. In contrast, the new drug is taken once daily and has a more consistent effect. "It is a useful alternative with fewer drug-drug and drug-food interactions and may be significantly easier to take," Patel said. If and when the drug is approved to treat atrial fibrillation, doctors will have to develop an appropriate way to transition patients from warfarin to the new drug, he said.
Dr. Gregory J. del Zoppo, a professor of medicine at the
University of Washington Harborview Medical Center in Seattle,
wrote an accompanying journal editorial. He said that the multiple
analyses in the new study had "muddied the waters" regarding
rivaroxaban's efficacy. "Some people do well with warfarin and
don't complain about one blood draw a month and watch what they
eat," he said. "For those folks, warfarin is still the
On the other hand, the new agent may be an option for people who
are more difficult to manage on warfarin, he added. "There are a
number of people who are difficult to control and for whom the
monitoring is complicated and intrusive, and they have to go
monthly or weekly to have blood drawn," he said.
Dr. Kousik Krishnan, associate professor of medicine at Rush
University Medical Center in Chicago, said that the new drug and
others like it "will be game-changing for all of us that treat
Warfarin has a lot of issues in terms of how it is managed and
side effects, and this medication will overcome almost all of them,
he said. "It is the same dose for everyone so there is no
monitoring," he said. "A great inconvenience is taken away and you
don't have to worry about diet as much and don't have to worry
about drug-drug interactions that are so commonplace with
warfarin," he said.
"We have this old drug that is well-tested and been on the market for decades, [and] we have these new medications that don't have the same length of track record, but in large studies, they have very good safety and efficacy data and they decrease some of the Achille's heels of warfarin," he said. "We won't lose anything in stroke prevention and we will gain on these other fronts."
Dr. Ranjit Suri, the director of the Electrophysiology Service
and Cardiac Arrhythmia Center at Lenox Hill Hospital in New York
City, said that "we are excited to have alternatives to warfarin,
and the simplicity of use is attractive because there is less need
for monitoring and it is probably as effective as warfarin."
This new agent may be the best choice for individuals at risk
for intracranial hemorrhage due to personal or family history of
stroke and/or other factors, as well as who have a hard time
getting their INR in check.
But there are some unknowns, Suri warned. Vitamin K is an
antidote to warfarin in the event of an overdose, but there are no
known antidotes to the new drugs yet -- a caution that del Zoppo
And then there's cost: del Zoppo worries that the newer
medications, including rivaroxaban, may also be prohibitively
The American Heart Association provides information about
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