According to results of a clinical trial presented at a meeting of the American College of Cardiology in Chicago, the proposed blood thinner Vorapaxar does appear to reduce the risk of dying from a heart attack or stroke by about 20% among individuals who have suffered a prior heart attack, but it nearly doubled the risk of internal bleeding.
The phase III trial tested Vorapaxar with standard therapy and compared the results to patients given a placebo. Part of the study was halted after patients with a history of stroke began suffering higher rates of brain hemorrhaging.
Merck is attempting to release the drug as the latest in a new generation of blood thinners, known as “direct thrombin inhibitors”, which inhibit the enzyme in the blood that causes blood to clot. Other approved mediations in the same class include Boehringer Ingelheim’s Pradaxa and Johnson & Johnson’s Xarelto.
The new blood thinners are supposed to be easier to use than Coumadin (warfarin), as they require less monitoring. However, concerns have grown in recent months about the risk of bleeding events, which can not be reversed when they occur.
While users of warfarin who suffer internal bleeding can be treated with Vitamin K to counter the blood thinning effects, Pradaxa and the other newer blood thinners in the same class do not have a quick fix.