NEW YORK (AP) – An experimental anti-clotting drug under development by Pfizer and Bristol-Myers did not work better than an older drug, the pharmaceuticals said on Nov. 14.

It was hoped that Eliquis, a pill, would be more effective and a potential alternative to Lovenox, an injectable drug, for patients who had been in the hospital for at least a month. Eliquis has not been approved in the United States.

In total, events including death, pulmonary embolism, or deep vein thrombosis occurred in 2.71% of Eliquis patients and 3.06% of Lovenox patients. Pfizer and Bristol-Myers said cases of bleeding were low in both groups, but bleeding was more common among patients treated with Eliquis.

The companies said more patients dropped out of the trial than expected.  Lovenox is marketed by Sanofi, and generic versions recently went on sale. The late-stage clinical trial evaluated the effect of the drugs on venous thromboembolisms, as well as deaths from that condition. Pfizer and Bristol-Myers Squibb Co. said patients who took Eliquis were less likely to die than patients who took Lovenox, but the difference was not statistically significant.

Eliquis, or apixaban, was approved in Europe in May for preventing blood clots in patients who have had hip or knee replacement surgery. The companies asked European regulators to approve the drug for patients with atrial fibrillation. They plan to ask the Food and Drug Administration to approve the drug before the end of 2011.

The Associated Press