Blood thinner warfarin faces promising new competition

In a new study, Johnson & Johnson and Bayer AG’s blood thinner Xarelto (Rivaroxaban) prevented strokes in patients with a atrial fibrillation (irregular heartbeat) better than the standard therapy with warfarin, without raising the risk of bleeding.

Irregular heartbeat, also known as atrial fibrillation (AF), occurs when the heart beats out of synch or is abnormally fast. Experts said that an estimate of 2.3 million Americans suffered from atrial fibrillation.

The study involved 7,111 patients on Xarelto and 7,125 patients on warfarin with average age 73. The participants were analyzed for an average of 19 months. Patients taking the drug, rivaroxaban, had a 21% reduction in the risk of having a stroke compared with patients being treated with warfarin.

When the analysis was adjusted to include people who stopped taking the drug or switched to another treatment before the trial was complete, 2.1% of those on Xarelto and 2.4% of those on warfarin had a stroke or a clot, a difference so small it could be due to chance.

A large number of people are forced to stop taking warfarin because of the need for numerous doctor visits to constantly adjust the dose of the drug. It also interacts with many other medications and foods. Warfarin, which inhibits clotting, is so often linked to major bleeding that the Food and Drug Administration in 2006 asked its maker, Bristol-Myers Squibb, to notify consumers with a black box warning, FDA’s strongest safety alert.

The research puts Xarelto in the position to take at least a third of the market from warfarin, following the approval of a rival drug called Pradaxa in the U.S. last month, Savant Ahmed, a London-based analyst for the Royal Bank of Scotland, said in an e-mail. Bayer has estimated the market for new blood-thinners including Xarelto could surpass $14 billion in annual sales.