Experimental Drug Drops Clot Risk

Vorapaxar lowers PAD blood clot risk but increases chance of serious bleeding

(RxWiki News) An investigational drug appears to offer significant improvements for patients with peripheral artery disease (PAD), a recent trial found.

Experimental drug, vorapaxar, capable of blocking platelets, reduced the probability that patients would require surgery to open clogged arteries in the legs. 

"Talk to your doctor about methods for improving PAD symptoms."

Marc P. Bonaca, MD, MPH, lead investigator and an instructor of medicine at Harvard Medical School and Brigham and Women’s Hospital, noted that most PAD therapies have focused on reducing the risk of heart attack and stroke in patients with PAD.

The new study demonstrated that treatment also can be offered to reduce limb-threatening blood clots or the need for artery-opening procedures such as revascularization.

During the study, researchers followed 3,787 PAD patients who were randomly assigned to receive standard care or standard care plus vorapaxar the first drug developed in a new class of drugs called PAR-1 antagonists.

The patients were selected from 26,449 participating in the Thrombolysis in Myocardial Infarction study group, which examined the drug's effectiveness in preventing cardiovascular events in those who had previously suffered a heart attack or stroke, or who had PAD.

The larger trial showed a significant reduction in heart events among patients taking vorapaxar.

Researchers found that 18.4 percent of patients taking vorapaxar required revascularization to restore blood flow compared to 22.2 percent who did not take the drug.

Additionally, fewer patients taking the drug were hospitalized for blood clots in their arms or legs at 2.3 percent versus 3.9 percent.

Among those taking the drug, 11.3 percent experienced a major cardiovascular event such as a heart attack compared to 11.9 percent of patients not taking the medication. The difference wasn't considered statistically significant.

However, as compared to those who did not take the drug, vorapaxar users had an increased risk of moderate to severe bleeding, though no fatal bleeding was reported. Of those who took the drug, 7.4 percent experienced significant bleeding compared to 4.5 percent of patients not taking the medication.

“This is the first outpatient therapy that has been shown to reduce the risk of blood clots and the need for artery opening revascularization procedures in the legs in patients with PAD,” Dr. Bonaca said, noting that the drug may work double duty by targeting platelets, and also artery wall cells important to artery function. "The benefits observed may be due to drug activity at both sites."

Investigators are currently evaluating whether treatment with the drug improves lower body circulation, allowing severe PAD patients to walk further without pain.

The findings, funded by drugmaker Merck, were recently presented at an American Heart Association’s Emerging Science Series webinar.

Review Date: 
June 19, 2012