New Anticoagulant Pill Works Well in Trial

WEDNESDAY, June 17 (HealthDay News) -- The new anti-clotting pill rivaroxaban (Xarelto) lowers the risk of stroke, heart attack and death in patients who have had a heart attack or suffer from unstable angina, a new trial shows.

Rivaroxaban is a pill that blocks factor Xa, which is involved in blood clotting. In earlier studies, the drug was effective in preventing venous thromboembolism (blood clots in the legs) after orthopedic surgery, although some increased risk in bleeding episodes was seen. In this phase II trial, researchers tested the safety and efficacy of the drug at various doses.

"The use of an oral factor Xa inhibitor in patients stabilized after an acute coronary syndrome increases bleeding in a dose-dependent manner, and might reduce major ischemic outcomes," said lead researcher Dr. Jessica L. Mega, from the Cardiovascular Division at Brigham and Women's Hospital in Boston. "On the basis of these observations, a phase III study of low-dose rivaroxaban as adjunctive therapy in these patients is underway."

The report is published in the June 17 online edition of The Lancet.

In March, a U.S. Food and Drug Administration advisory panel voted 15-2 that rivaroxaban, a long-sought alternative to commonly used blood thinners that have to be injected and are tricky to monitor, had benefits that outweighed its bleeding risks. Although the FDA is not bound by the panel's decision, it typically follows suit on these recommendations.

For the study, Mega's group treated 3,491 patients who had had heart attacks or unstable angina with either aspirin or aspirin plus the anti-clotting drug clopidogrel (Plavix).

The patients were then randomly assigned to a placebo or rivaroxaban, at doses ranging from 5 milligrams to 20 milligrams a day. The researchers looked for any significant bleeding and deaths, heart attacks and stroke.

There was an increase in bleeding episodes with rivaroxaban. Over six months, the researchers found that risk increased with dosage. At 5 milligrams, the risk increased 2.2 times, while the 20-milligram dose raised the risk fivefold.

However, patients receiving rivaroxaban had a 21 percent reduction in heart attacks, strokes, ischemic events and deaths compared with patients taking placebo. For heart attack, stroke and death alone, the risk was reduced by 31 percent compared with placebo, the researchers found.

"In this study, rivaroxaban was associated with a dose-dependent increase in clinically significant bleeding events, with a trend towards a reduction in the primary efficacy endpoint of death, myocardial infarction, stroke or severe recurrent ischemia requiring revascularization," Mega and colleagues wrote. "Regarding the main secondary efficacy endpoint, rivaroxaban reduced the rate of death, myocardial infarction or stroke."

Dr. Hitinder S. Gurm, from the University of Michigan Cardiovascular Center and co-author of an accompanying journal editorial, said the study showed no benefit in patients who are using aspirin and Plavix, although there was a suggestion of a benefit when the drug was used with aspirin alone.

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