The U.S. Food and Drug Administration approved Sunharbo (asundexian) on November 9, 2026, as a new option to reduce stroke risk in certain adults who recently had an ischemic stroke or a high-risk transient ischemic attack (TIA). Sunharbo stroke prevention involves using the medicine together with antiplatelet therapy—not as a replacement for it.
According to the FDA’s approval announcement, Sunharbo is the first approved factor XIa (FXIa) inhibitor. Its approved use is limited to a specific group of adults, and the announcement identifies important bleeding risks and medication restrictions.
Who is eligible for Sunharbo stroke prevention?
The approval covers adults following a recent mild-to-moderate non-cardioembolic ischemic stroke or a high-risk TIA. A non-cardioembolic ischemic stroke is caused by a clot that did not originate in the heart. A TIA is often called a “mini-stroke.”
This is an option for secondary stroke prevention: reducing the risk of another stroke after a qualifying event. The approval does not cover everyone who has had a stroke or everyone considered at high risk.
One particularly important limit is atrial fibrillation. The FDA states that Sunharbo is not approved for stroke prevention in patients with that condition. People seeking information about treatment after a stroke or TIA need a clinician to determine whether their event and medical history fit the approved use.
What did the clinical trial find?
The approval was supported by OCEANIC-STROKE, a phase 3 study involving 12,327 adults. It was a multicenter, randomized, double-blind, placebo-controlled trial. Participants had a recent non-cardioembolic ischemic stroke or a high-risk TIA and were assigned to Sunharbo or placebo within 72 hours of symptom onset.
Both groups also received antiplatelet therapy. Over a median treatment period of 14.2 months, Sunharbo reduced the risk of ischemic stroke by 26% compared with placebo.
That figure describes a relative reduction between the groups, not a 26-percentage-point reduction in an individual’s risk. The FDA announcement does not provide the absolute stroke rates, so it does not show how many fewer strokes occurred per 100 people treated.
Bleeding risks and other side effects
The overall major bleeding rate was similar in the Sunharbo and placebo groups. However, the FDA reported increased major bleeding with Sunharbo among patients older than 75 and during the first 90 days of treatment. Those findings are important even though the overall rates were similar.
Gastrointestinal bleeding occurred more often with Sunharbo than with placebo. Diarrhea was the most frequently reported adverse reaction, occurring in at least 3% of Sunharbo-treated participants.
What requires professional medical review?
Medication interactions, liver health, and upcoming procedures are important parts of assessing this treatment. The FDA does not recommend Sunharbo for patients with moderate or severe hepatic impairment.
The announcement also says that combined P-gp and strong CYP3A4 inducers, such as carbamazepine, may reduce Sunharbo’s effectiveness, and using them together is not recommended. A clinician’s review of other medicines is therefore relevant before treatment decisions.
The FDA also specifies temporary withholding around elective surgery or invasive procedures and after thrombolysis for acute ischemic stroke. Those situations require clinician-managed decisions rather than self-directed changes. The approval announcement does not provide an individualized treatment plan.
Frequently Asked Questions
Is Sunharbo used instead of antiplatelet therapy?
No. The approved use is in combination with antiplatelet therapy. Both groups in the supporting clinical trial received antiplatelet treatment.
Is Sunharbo approved for people with atrial fibrillation?
No. The FDA explicitly states that Sunharbo is not approved for stroke prevention in patients with atrial fibrillation.
Does the similar overall bleeding rate mean there is no bleeding concern?
No. Major bleeding was increased in patients older than 75 and during the first 90 days. Gastrointestinal bleeding was also more common with Sunharbo than with placebo.
