New Drug to Prevent Blood Clots

In a clinical trial, an experimental drug has shown promise in preventing the formation of blood clots in patients with coronary artery disease who have had angioplasty or bypass surgery or are at risk of a heart attack. The drug prevents clot formation earlier in the coagulation process than other agents, say cardiologists from Duke University Medical Center (Durham, NC, USA), who led the trial.

The study involved 73 patients with clinically stable coronary artery disease, of whom 68% had experienced a prior heart attack and 86% had undergone angioplasty or bypass surgery. The patients were randomized to either placebo or one of four escalating doses of factor Xa inhibitor. The researchers found no statistically significant difference in bleeding complications among all five groups, and no adverse changes in kidney or liver function. Hemoglobin and platelet counts remained stable in all groups.

A big disadvantage of coagulation therapy is the potential for bleeding complications. The new drug inhibits the action of factor Xa, the most pivotal of all known clotting factors involved in the complex cascade of biochemical events that leads to clot formation. When factor Xa is activated, it responds by converting prothrombin into the enzyme thrombin, which then converts circulating fibrinogen into the protein fibrin, the primary building block of a blood clot. The advantage of interrupting the clotting cascade at the point of factor Xa activation is that it sits at the intersection of the two classical pathways for blood clot formation and limits the generation of thrombin.

"Based on the results of this small phase I trial, this new anticoagulant appears to effectively inhibit factor Xa while being well tolerated,” said Dr. Christopher Dyke, senior cardiology fellow at Duke Clinical Research Institute, who presented the findings at the annual meeting of the European Society of Cardiology in Stockholm (Sweden).




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