By MATTHEW PERRONE AP Business Writer COLLEGE PARK, Md. (AP) — Government health advisers said Thursday the benefits of an experimental anticlotting drug from Johnson & Johnson outweigh its risks, including bleeding and incomplete data about liver side effects. The Food and Drug Administration's panel of cardiology experts voted 15 to 2 in favor of J&J's rivaroxaban, which if approved, would be the first new pill-based anticlotting drug in a half-century. The agency is not required to follow the advice of its panelists, though it usually does. J&J and partner Bayer have asked the FDA to clear their once-daily pill to stop blood clots in the legs of patients who have undergone hip or knee replacement surgery. More than 800,000 U.S. patients undergo the procedures each year, and clots are a common side effect that can prove deadly if they break loose and travel to the lungs. In four studies of knee and hip replacement patients, rivaroxaban cut the risk of blood clots or death in half, to 0.6 percent, compared with patients taking Sanofi-Aventis' Lovenox, the top-selling drug currently used by orthopedic patients. But J&J's drug also caused significantly more internal bleeding, according to the same studies, which included over 12,000 patients. Panelists questioned the strength of J&J's findings on blood clot prevention, which were primarily based on medical images of patient's veins. They also questioned the comparability of the company's studies, which ranged in duration from less than two weeks to five weeks. Despite discussion points from the FDA that seemed to favor delaying a decision on the drug, most panelists said the data now available were enough to grant approval. "I think we're very pleased with the discussion and outcome and look forward to an ongoing dialogue with the agency," said Dr. Peter DiBattiste, J&J's head of cardiology. At the urging of regulators, panelists also scrutinized the effects of the drug on the liver. A similar drug from AstraZeneca was removed from the market in 2006 because of evidence it caused liver damage. While it was never available in the U.S., because it was rejected by the FDA, it was used by hundreds of patients in Europe. "We should not rush into this, we should wait until we get more data," said panelist Dr. Sidney Wolfe, a director of the consumer advocate Public Citizen. "We haven't been able to fully characterize the potential for severe liver dysfunction." Despite Wolfe's urgings and a cautious tone from the FDA, a majority of panelists said the drug did not appear to cause liver damage in the short term. "I think we have enough safety and efficacy data to approve it for short term use, with the caveat that practitioners should not prescribe it for alternate uses, particularly long-term uses," said Dr. Peter Gross, Professor of medicine at New Jersey Medical School. As the first oral anticlotting drug in decades, regulators raised concerns that doctors would begin using the drug for uses outside the relatively narrow indication for knee and hip replacement patients. New Brunswick, N.J.-based J&J has touted its product as safer and more effective than older drugs like warfarin, which has been used since the 1950s. That drug requires patients to undergo frequent blood tests because a too-high or too-low dose can lead to strokes or dangerous bleeding. As a pill, rivaroxaban would also enjoy a convenience benefit over Sanofi's Lovenox, which must be injected. The FDA is scheduled to make a decision on the drug by May 28. Bayer Healthcare, a division of the German conglomerate, would receive a royalty as high as 30 percent on U.S. sales, under an agreement with J&J. Bayer already markets the drug in Europe under the brand name Xarelto. Approval for the knee and hip replacement patients will probably not be a huge moneymaker for J&J, according to Wachovia Capital Markets analyst Larry Biegelsen, who estimates initial sales of about $300 million per year. But the company is studying the drug in more than 60,000 patients for a variety of uses, including prevention of stroke. With those approvals the drug could grow into a blockbuster product, with sales of $1.6 billion by 2013, Biegelsen estimated.