A New Pill Could Reduce the Risk of Having a Second Stroke

12 Nov 2026, 19:59 by Alice Park · TIME

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On November 9, the U.S. Food and Drug Administration (FDA) approved a new type of medication to reduce the risk of strokes in certain populations.

Asundexian, which will be sold under the brand name Sunharbo, is a daily pill that is the first to target a specific factor in the blood-clotting process that can contribute to stroke. In a study submitted to the FDA by Bayer, researchers found that the drug, when combined with an antiplatelet therapy such as aspirin, reduced the risk of an additional stroke by 26% in just over a year compared to people who received placebo and the antiplatelet therapy. The drug is approved for people who have recently had an ischemic stroke, which occur when clots block blood flow to the brain, or a transient ischemic attack caused by a temporary blockage of blood flow to the brain that doesn’t cause permanent damage.

“The data is quite robust, and the feedback from the international stroke community is positive,” says Dr. Ashkan Shoamanesh, professor of medicine at McMaster University, who co-led the trial. “We’re eager to have this on hand as soon as possible for patients.”

There are two types of strokes: ischemic strokes, caused by blockages in the blood vessels, can impede blood flow to critical organs including the brain, and hemorrhagic strokes, caused by weakened blood vessels that burst in the brain and cause excessive bleeding. About 87% of strokes in the U.S. are ischemic.

Each year, about 795,000 people in the U.S. have a stroke, and nearly one in four strokes occur in people who have previously had one. Recurrent strokes represent an unmet treatment challenge, says Shoamanesh. But treating ischemic strokes requires using just enough clot-breaking—or blood thinning—medications to dissolve the blockage without causing excessive bleeding. Asundexian appears to do just that. The 26% reduction in stroke risk occurred without any significant increase in bleeding events, according to Bayer’s data. “We used to always have a challenging balancing act,” says Shoamanesh. “Here we have the major benefits without the bleeding risk, so there is a large amount of excitement.”

Researchers have known for years that some people born with a genetically driven lower risk of stroke have lower levels of a compound involved in blood clotting, called Factor XIa, in their blood. It's a minor contributor to forming clots when the body experiences a major bleeding trauma like an injury, but it plays a bigger role in smaller vessel ruptures, some of which can contribute to stroke, says Shoamanesh.

It took more than a decade for scientists to turn that observation into a viable medication, says Dr. Christoph Koenen, chief medical officer at Bayer. But asundexian prevents small clots that may form in the vessels from becoming larger ones that can grow to block blood flow. One of the findings that most impressed the researchers was that "it didn’t matter how old people were, from what part of the world, what their medical history was, or what type of ischemic stroke they had—all of the patients seem to benefit similarly from the treatment,” says Shoamanesh.

Given the encouraging results in reducing the risk of recurrent strokes, Koenen says Bayer is exploring "if there are other benefits of asundexian we can bring to different patient populations.”

Asundexian will be available starting in November. Shoamanesh expects that in order to truly benefit from the drug, patients will have to take the daily pills for the rest of their lives. Data that tracked some of the study participants for several more years showed that those on the drug continued to show lower risk of stroke compared to those taking placebo. “That means that the drug continued to provide an advantage even at later time points,” he says. “So we expect this to be a lifelong drug based on the data. And we expect this will be the new standard of care.”