Bayer said it received regulatory authorization to launch a drug to prevent recurrent stroke in China, winning the first approval for a new class of blood-thinning medicines.

The German pharmaceutical group has been counting on the drug--which is known as asundexian and will be marketed under the brand name Sunharbo--to replace lost sales of its blockbuster blood thinner Xarelto after it went off patent.

China's nod hands Bayer the first approval worldwide for a class of drugs called Factor XIa inhibitors, the company said Monday. The drugs aim to slow down the activity of a protein that regulates how the body forms clots without increasing the risk of bleeding.

Further regulatory applications are currently under review around the world, the company said.

Bayer said China's National Medical Products Administration approved the medicine to reduce the risk of stroke in adults after a after noncardioembolic ischemic stroke or high-risk transient ischemic attack--when the blood supply to the brain is disrupted. Stroke is the leading cause of death and disability in China, it added.

The decision followed a priority review and was based on positive data from a pivotal study, Bayer said.

The company in November last year said a late-stage clinical trial showed its drug, in combination with antiplatelet therapy, reduced the risk of a recurrent stroke without a significant increase in major bleeding. The study lifted Bayer's stock as it gave the company a path to seek regulatory approval for a drug that had previously failed a study for primary stroke prevention.

Bristol Myers Squibb and Johnson & Johnson are developing another experimental drug that uses the same mechanism.

Christine Roth, head of global product strategy and commercialization for Bayer's pharmaceuticals business, said in an interview that the drug will set a high bar for rivals and should have a one-year head start before the next competitor enters the market.

"It's a high bar, both on the efficacy and the bleeding risk," Roth said. "That product will carry us through the next patent cliff."