Warfarin, a drug discovered and patented at the University of Wisconsin, has more negative side effects than its competitor aspirin, according to a recent study published in last month’s New England Journal of Medicine.

Though warfarin, commonly used to treat partial brain artery blockages, is equally as effective as aspirin, scientists warn some individuals with certain conditions may be more at risk for fatalities.

The study took almost two years and involved approximately 570 patients with brain artery blockages, known as intracranial arterial stenosis, a common cause of stroke.

Warfarin provided no benefit over aspirin in the study, according to research led by Marc Chimowitz, M.D. of Emory University released in the study. Chimowitz urged that aspirin should be used in place of warfarin if patients suffer from intracranial arterial senosis.

In the study, researchers reported patients given warfarin were twice as likely to die from vascular causes as those taking aspirin. Patients taking warfarin were also found to be three times as likely to suffer major hemorrhaging compared to patients given aspirin. An increased risk of death from nonvascular events in people taking warfarin was also identified in the research.

Before this study, doctors prescribed warfarin and aspirin for treating brain artery blockages, but did not know if one drug was more appropriate to use than the other.

“This trial is good news,” said John Marler, M.D., of the National Institute of Neurological Disorders and Stroke. “A simple low-cost drug works just as well as one that requires complicated and expensive monitoring and dose adjustments.”

But the new findings of the study will have little effect on WARF’s profits or research funded through these profits, according to Andrew Cohn, public relations director for WARF.

“[Warfarin] has been off patent for 20 years,” Cohn said. “So it doesn’t really affect us.”

Though the findings of the study indicate taking warfarin for partial blockage of brain arteries may cause side effects, patients taking warfarin for other conditions should not stop taking warfarin, Chimowitz said in a release.

“The results of the study are only relevant to people with intracranial stenosis,” Chimowitz said.

However, doctors who prescribe warfarin should be cautious, said Tom Bull, a pharmacist for Aurora Pharmacy.

“Warfarin dosing needs to be monitored fairly closely,” Bull said. “And there are a lot more drug interactions that occur with warfarin than with aspirin.”

Efficacy of warfarin also depends on a patient’s diet, Bull added.

The drug also has a detailed history at UW, where WARF has accrued millions of dollars from sales.

Patented at the University of Wisconsin in 1945, warfarin is a highly effective anti-coagulant lethal to humans and animals in high doses.

Warfarin was named for the Wisconsin Alumni Research Foundation, or WARF, and was discovered by Professor K.P. Link in the Department of Biochemistry.

Warfarin was initially used as rat poison due to its dramatic effects in inhibiting blood clotting but was later developed as a treatment for blockage due to intracranial arterial stenosis. Such blockages cause about 10 percent of strokes in the U.S. each year, according to the National Institutes of Health.