Data from a phase II study of an investigational drug designed to block formation of blood clots show potential for added protection against a second heart attack or stroke among patients who are already taking state-of-the-art prevention therapy.
While the results of the study did not show a statistically significant difference in ischemic events among any of the four doses of apixaban evaluated, trends emerged that support further study, according to researchers at the Duke Clinical Research Institute.
Apixaban targets the activity of Factor Xa, one of several enzymes involved in process of blood coagulation. The drug is just one of several new anti-clotting agents under development. Physicians say the need for safer, better anticoagulants is critical because current therapies fall short of therapeutic goals or are especially difficult to manage and increase the risk of bleeding.
"One of the most vexing problems in cardiology is identifying the right combination of drugs that can inhibit clot formation but not increase the risk of serious bleeding," said study lead John Alexander, M.D., a cardiologist at Duke University Medical Center, who presented the findings today at the European Society of Cardiology meeting in Munich.
Millions of patients world-wide take anti-clotting drugs on a regular basis. Most are prescribed aspirin, clopidogrel (also known as Plavix or Iscover) and/or warfarin.
"Warfarin is clearly effective as an anticoagulant, but it is especially hard to manage properly and safely," Alexander said. "What's driving research in this area is the fact that although aspirin and clopidogrel both offer heart attack patients important protection against blood clots, there is still room for improvement. Studies show that a significant number of patients taking aspirin and clopidogrel will still experience some sort of problem related to a blood clot. Adding warfarin increases the likelihood of bleeding complications at a higher rate than anybody is comfortable with."
Alexander, along with Professor Lars Wallentin from the Uppsala Clinical Research Center in Sweden and other colleagues, studied the use of apixaban in 1,715 patients from 14 countries throughout Europe and North America who had suffered a recent heart attack. Roughly two-thirds of the patients had undergone angioplasty to clear blocked arteries and 99 percent of them were taking either aspirin or aspirin and clopidogrel.