An advisory committee of the U.S. Food and Drug Administration recommended approving a new anticoagulant drug for stroke prevention Thursday, rejecting an FDA staff analysis that found flaws in a study.

The panel's vote on Xarelto was 9-2 with one abstention.

Two days ago, the FDA staff had presented a critical report, saying a study meant to show that the new medicine works better than decades-old Warfarin didn't clearly prove it was safe and effective.

Xarelto, from Johnson & Johnson and Bayer AG, might replace Warfarin to prevent strokes among patients with a type of faulty heartbeat.

Warfarin, which is cheaper, has been used for stroke prevention for almost 70 years. But doctors need to regularly measure its levels in the bloodstream, which is not the case with Xarelto.

Warfarin, sold as Coumadin and other brands, has its own drawbacks. It's notoriously difficult to get the dose of the drug correct. Patients need frequent blood tests because too much of it can cause dangerous internal bleeding.

According to Johnson & Johnson and Bayer AG, Xarelto is more convenient for patients and has fewer side effects.

Xarelto is one of several experimental drugs being developed as a replacement for Warfarin, a medicine originally derived from rat poison that has been used safely and effectively for seven decades to prevent strokes.

Three new drugs have been developed to replace Warfarin. While Xarelto is given once in a day, the other two drugs require twice-a-day dosing.

Analysts largely expect that Xarelto would generate peak sales of $1 billion or more.