by Nancy Shute
A common form of irregular heartbeat called atrial fibrillation can cause blood clots, putting people at increased risk of stroke. The anticoagulant drug warfarin is used to reduce that risk, but since people respond to it very differently, it requires careful monitoring to avoid the risk of heavy bleeding. Now, researchers say a new drug called rivaroxaban looks to be as good as warfarin in preventing strokes.
About 2.3 million people in the United States have atrial fibrillation, so drug manufacturers have been eager to come up with oral anti-clotting drugs to replace warfarin - drugs that don't require blood tests and frequent fiddling with doses.
Rivaroxaban, one of those new drugs, is just as good as warfarin at reducing the risk of stroke, according to a new study published online in the New England Journal of Medicine. That study followed 14,264 patients who took either rivaroxaban (brand name Xarelto) or warfarin (sold as Coumadin and other brand names). None of the study participants knew which drug they were given.
The study actually called rivaroxaban "noninferior" to warfarin, a double negative that must have made executives at Johnson & Johnson, parent of rivaroxaban, want to weep. That term reflects the fact that the researchers had a hard time comparing it directly to warfarin, partly because the people taking warfarin were able to maintain good levels of the drug in their blood just a little more than half the time.
The study also found that rivaroxaban didn't pose a greater risk of serious bleeding than did warfarin. And for some types of bleeding, rivaroxaban performed better. Johnson & Johnson and Bayer, which both make rivaroxaban, funded the study.
Last month the Food and Drug Administration approved rivaroxaban to prevent clots in patients having knee or hip replacement surgery. And last year, the agency approved another new anti-clotting drug, dabigatran (sold as Pradaxa). Both drugs are clearly aimed at the big market for anti-stroke drugs in people with atrial fibrillation, though they aren't yet approved for that. Stay tuned.
Although Pradaxa is pricey, running about $8 a day compared to $1 for warfarin, the new drugs may end up being easier to take, because they shouldn't require the close monitoring with blood tests that's now required with warfarin. But to date, it's not clear how much rivaroxaban will cost and whether it will be more affordable.