September 28, 2012 — A new study published in the September issue of Archives of Internal Medicine has found that the risk of bleeding may outweigh any benefit for several new blood-thinners — including Pradaxa, Xarelto, and the investigational drug Eliquis. The researchers compared the new blood-thinners versus a placebo for treating patients with Acute Coronary Syndrome (ACS), a condition caused by sudden, reduced blood-flow to the heart.
Blood-thinning drugs are supposed to dissolve blood clots and prevent future clotting. Pradaxa is approved to reduce the risk of stroke, which occurs when blood clots travel to the brain. Researchers wanted to investigate whether these drugs helped patients who were at risk of blood clots in the heart, a common cause of ACS.
The researchers gathered data from seven different clinical studies comparing the new drugs to a placebo, and conducted a meta-analysis. The studies involved more than 31,000 people who were given a new blood-thinner.
The researchers found a tripled risk of bleeding among patients who were given a blood-thinning drug, but no improvement in overall survival rates. Although the blood-thinning drugs slightly reduced the patients’ risk of a thrombotic event (a blood clot), the researchers cautioned: “Despite receipt of dual antiplatelet therapy, patients after an ACS remain at significant risk for thrombotic events.”
The researchers also warned:
“For net clinical benefit, treatment with new-generation oral anticoagulant agents provided no advantage over a placebo. The use of anti-Xa or direct thrombin inhibitors is associated with an increase in major bleeding events, which might offset all ischemic benefits in patients receiving antiplatelet therapy after an ACS.”
Furthermore, several studies had to be ended prematurely when patients taking the blood-thinners suffered severe side effects.
For several decades, Coumadin (warfarin) has been the drug of choice to reduce the risk of blood clots. In 2010, Pradaxa (dabigatran) became the first major competitor, and was soon followed by Xarelto (rivaroxaban). Another drug, Eliquis (apixaban), has yet to gain approval from the FDA. Pradaxa is a direct thrombin inhibitor, whereas Xarelto and Eliquis are Xa-inhibitors.
Dozens of Pradaxa lawsuits have been filed by patients who allege the drug-maker, Boehringer Ingelheim, failed to adequately warn about the bleeding risks associated with Pradaxa. Although all blood-thinners have a risk of bleeding, Pradaxa has no simple reversal mechanism. Warfarin can be reversed with a dose of Vitamin K, but the blood-thinning effects of Pradaxa can only be reversed by several hours of blood dialysis to mechanically remove the drug from the bloodstream. In an emergency, this could be fatal.