FDA Approves Sunharbo, First Factor XIa Drug to Cut Repeat Stroke Risk by 26%

The U.S. Food and Drug Administration has approved Sunharbo, the first medicine in a new class of blood thinners, giving stroke survivors a once-daily pill that cut second-stroke risk by over a quarter in a large trial. The Sunharbo FDA approval, announced on Monday, November 9, 2026, covers adults recovering from a recent mild-to-moderate stroke or high-risk mini-stroke, taken with standard antiplatelet therapy. It is the first factor XIa inhibitor ever cleared by the FDA.

For stroke survivors, it is rare good news: a repeat stroke is often more disabling than the first, yet existing blood thinners force a hard trade-off between clot protection and bleeding. Sunharbo was designed to break it.

Key Points

• The FDA approved Bayer’s Sunharbo (asundexian) 50 mg tablets on November 9, 2026, the first factor XIa inhibitor approved in the United States.
• In the OCEANIC-STROKE trial of 12,327 patients, Sunharbo cut recurrent ischemic stroke by 26% versus placebo, with no statistically significant rise in major bleeding.
• A once-daily 50 mg tablet taken with antiplatelet therapy, started within 72 hours of a stroke or high-risk mini-stroke.
• Not approved for stroke prevention in atrial fibrillation, and not recommended in moderate or severe liver impairment.
• Bayer expects shipping to begin in mid-to-late November 2026; list price is $748.50 for a 30-day supply.

What Happened

The FDA announced the approval on Monday, November 9, 2026, granting it to Bayer HealthCare Pharmaceuticals Inc. Sunharbo — generic name asundexian — is approved to reduce stroke risk in adults after a recent mild-to-moderate noncardioembolic ischemic stroke (NIH Stroke Scale score of 15 or less) or a high-risk transient ischemic attack (TIA).

Approval was based on the global phase 3 OCEANIC-STROKE trial (NCT05686070): 12,327 patients at 702 centres in 37 countries, assigned within 72 hours of stroke or high-risk TIA to Sunharbo 50 mg once daily or placebo, both groups also on antiplatelet therapy. Over a median of 14.2 months, recurrent ischemic stroke occurred in 6.2% on Sunharbo versus 8.4% on placebo — a 26% relative reduction (hazard ratio 0.74, p < .001). The FDA granted Fast Track and Priority Review designations.

Background: Why Stroke Survivors Need a New Option

Stroke remains a leading cause of disability and death in the United States, and surviving one does not end the danger: the weeks and months after a first stroke or TIA carry the highest risk of a second event. For decades, prevention has relied on antiplatelet drugs such as aspirin and clopidogrel, and on older anticoagulants. The problem is balance: the same mechanism that stops a clot in the brain can also stop blood clotting when needed — after a fall, during surgery, or in the gut. That bleeding risk is why many patients cannot take stronger blood thinners.

Factor XIa sits at a different point in the clotting cascade, and research suggests blocking it can prevent stroke-causing clots while leaving much of normal clotting intact. Sunharbo is the first drug in this class to reach patients.

Sunharbo FDA Approval: What the OCEANIC-STROKE Trial Showed

The 26% relative reduction is a large effect for a preventive medicine: about two fewer strokes per 100 patients treated over roughly 14 months.

Bleeding data were equally important: overall major bleeding was similar in both groups, unusual for an anticoagulant. But the FDA also carried clear cautions — major bleeding was higher with Sunharbo in patients over 75 and in the first 90 days of treatment, and gastrointestinal bleeding was more common. The most frequent side effect was diarrhea, in at least 3% of patients.

There are firm limits. Sunharbo is not approved for stroke prevention in atrial fibrillation, because the trial did not study that group. It is not recommended in moderate or severe liver impairment, and it should not be combined with combined P-gp and strong CYP3A4 inducers, such as carbamazepine, which may reduce its effectiveness. The FDA also says it should be withheld for at least 24 hours before elective surgery or invasive procedures, and for at least 24 hours after clot-busting thrombolysis.

Reactions

“Stroke is a leading cause of disability and death in the United States, and survivors are at risk of having another stroke,” said Dr. Hylton V. Joffe, director of the Office of Cardiology, Hematology, Endocrinology, and Nephrology in the FDA’s Center for Drug Evaluation and Research. “Today’s approval represents a meaningful advance for patients and health care providers seeking a new option for secondary stroke prevention.”

Why It Matters

For stroke survivors, it offers something missing until now: a preventive option without the bleeding trade-off of older blood thinners. If trial results hold up in practice, the drug could prevent thousands of second strokes a year — events that often leave people unable to walk, speak or live independently. The list price of $748.50 for a 30-day supply puts it among expensive specialty medicines, and insurance coverage will shape its use.

The approval also arrives as the FDA this week ordered Ozempic, Wegovy, Mounjaro and Zepbound to carry warnings about vision loss risk, and the government awarded $10 billion in rural health funds to all 50 states as Medicaid cuts loom — so access, not just approval, will decide how many benefit.

What Happens Next

Bayer expects to begin shipping in mid-to-late November 2026, so Sunharbo could reach pharmacies within weeks. Doctors will be able to prescribe it to eligible patients — adults after a recent mild-to-moderate stroke or high-risk TIA — alongside existing antiplatelet therapy. Attention turns now to Europe and Japan, which are reviewing asundexian, and to real-world safety data, particularly in patients over 75, where the trial showed a higher bleeding risk.

Patients who recently had a stroke or TIA should ask their doctor whether Sunharbo is appropriate. It is not a replacement for antiplatelet therapy and is not suitable for everyone, including people with atrial fibrillation or significant liver problems. What has changed is that, for the first time, doctors have a factor XIa inhibitor to offer.

Frequently Asked Questions

What is Sunharbo?

Sunharbo is the brand name for asundexian, a once-daily 50 mg Bayer tablet and the first factor XIa inhibitor approved by the FDA — a new blood thinner designed to prevent stroke-causing clots while disrupting normal clotting less.

Who can take Sunharbo?

Adults who recently had a mild-to-moderate noncardioembolic ischemic stroke or a high-risk mini-stroke, taken with antiplatelet therapy. Not approved for stroke prevention in atrial fibrillation, nor recommended for moderate or severe liver impairment.

How effective is Sunharbo at preventing a second stroke?

In the OCEANIC-STROKE trial of 12,327 patients, Sunharbo cut recurrent ischemic stroke by 26% versus placebo over a median of 14.2 months: 6.2% on the drug versus 8.4% on placebo.

Does Sunharbo increase the risk of bleeding?

Overall, major bleeding was not statistically significantly higher than with placebo, but it was increased in patients over 75 and during the first 90 days, and gastrointestinal bleeding was more common. The most frequent side effect was diarrhea.

How much does Sunharbo cost, and when will it be available?

List price is $748.50 for a 30-day supply; Bayer expects shipping to begin in mid-to-late November 2026. What patients pay depends on insurance.