March 13 (HealthDay News) -- A drug derived from the magnolia tree appears to be safe and tolerable in preventing blood clots, according to a phase 2 study conducted by researchers at the Duke Clinical Research Institute.

The trial included 1,030 people, 45 years and older, who were scheduled to undergo either percutaneous coronary intervention (PCI) -- a procedure to clear clogged arteries and keep them open with stents -- or angiography and then PCI. People having PCI are usually prescribed drugs, such as aspirin or clopidogrel, to prevent potentially dangerous blood clots.

The study participants were randomly assigned to receive one of three doses (10, 20 or 40 milligrams) of the new drug, called SCH 530348, or a placebo. Aspirin and clopidogrel were not prescribed as part of the study but were allowed, and 95 percent of people in the study took both drugs, the researchers said.

They found that the new drug was generally tolerable at all dosing levels and did not increase bleeding, even when taken with aspirin and clopidogrel. Bleeding occurred in 2 percent of the 129 people who took 10 mg, in 3 percent of those who took 20 mg, in 4 percent of those who took 40 mg and in 3 percent of the placebo group.

Participants were also given different maintenance doses of the drug. Bleeding occurred in 2 percent of those who took 0.5 mg, in 4 percent who took 1 mg, in 3 percent who took 2.5 mg and in 2 percent of those who took the placebo.

The findings were released online and published in the March 14 print issue of The Lancet. The study was funded by Schering-Plough, and a number of the study's authors received consulting fees from the drug maker or own stock in the company.

The researchers said that SCH 530348 appears able to uncouple two important functions of thrombin in the formation of blood clots and that it might offer a better way to control bleeding and blot clot formation during PCI. Thrombin is a protein in the blood that activates platelets, particles that clump together to form the scaffolding of a clot. Thrombin also helps produce fibrin, a protein that plays an important role in repairing damaged tissue.

"One of the intriguing things about this new investigational compound is that it blocks the thrombin receptor that activates platelet formation yet preserves the beneficial activity of fibrin formation." Dr. Richard Becker, a cardiologist and the study's lead author, said in a Duke news release. "And the data to date indicate the compound does this even when patients are taking aspirin and clopidogrel."

An international, phase 3 study of the new drug is under way, the researchers said.

SOURCE: Duke Medicine, news release, March 12, 2009