Vorapaxar, an experimental anti-clotting drug that Merck & Co. is developing, increased risk of bleeding internally in a study, the second time it's shown that dangerous side effect.
Merck says the top-line results from a study called TRA-2P show vorapaxar, when added to standard anticlotting therapy, reduces risk of heart attack, stroke, death from heart disease or emergency heart surgery.
But the company says there was a significant increase in bleeding, including bleeding inside the skull. That intracranial bleeding was less common in patients who had not previously had a stroke.
A year ago, Merck halted another study because of the same bleeding problem.
Merck says it will present detailed results from the latest study at a March medical conference.
