Blood thinner drug Xarelto tied to more major side-effects - study

By Leroy Leo

Dec 21 (Reuters) - Older adults taking Bayer AG's blockbuster blood thinner pill Xarelto for a common type of irregular heart rhythm had significantly higher rates of serious bleeding and stroke compared to those taking rival pill Eliquis, a U.S. study showed.

Xarelto, also known as rivaroxaban, is sold in the United States by Johnson & Johnson arm Janssen Pharmaceuticals. Eliquis, also known as apixaban, was co-developed by Pfizer Inc and Bristol Myers Squibb.

The findings are drawn from Medicare claims data on 581,451 adults age 65 or older with atrial fibrillation. Among every 1,000 individuals, the combined rate of major bleeding events and strokes due to clogged arteries or hemorrhage was roughly 16 per year with Xarelto versus about 13 per year with Eliquis, researchers reported on Tuesday in JAMA.

After taking participants' other risk factors into account, the overall rate of these events was 18% higher with Xarelto, they said. Xarelto was tied to a 12% higher rate of clot-related stroke, a 26% higher rate of bleeding-related stroke, a 41% higher rate of fatal non-stroke bleeding, and a roughly doubled rate of non-fatal non-stroke bleeding.

Blood thinners are used in patients with atrial fibrillation to prevent the rhythm disorder from causing small clots in the heart that can cause strokes if dislodged.

The study cannot prove that Xarelto caused the adverse events. Still, it "provides pretty strong data that for treatment and stroke prevention in atrial fibrillation, apixaban is the better drug," said study leader Wayne Ray of Vanderbilt University School of Medicine in Nashville, Tennessee.

Xarelto was approved by the U.S. Food and Drug Administration in 2011 while Eliquis was approved a year later. Generic forms of Eliquis were approved in 2020, but Pfizer and Bristol Myers Squibb won a legal suit that allows them to hold a patent on the drug through March 2028.

An accompanying editorial in the journal said one potential explanation for the findings is that while Eliquis is taken twice a day, Xarelto is taken only once daily, which may lead to higher variability in drug levels in the body.

"Patients treated with rivaroxaban may therefore experience higher bleeding risk during high peak levels, and greater stroke risk during low trough levels," Dr. Peter Zimetbaum and colleagues at Beth Israel Deaconess Medical Center in Boston suggest in the editorial.

Restricting the analysis to older adults and lack of information on patients' adherence to dosing regimens were among the limitations of the study, the researchers said.

Bayer recorded nearly 3.5 billion euros ($3.95 billion) in Xarelto sales during the nine months ended September, while J&J recorded $1.8 billion. For Eliquis, Pfizer recorded $4.47 billion in sales during the same period, while Bristol Myers Squibb garnered $8.09 billion. (Reporting by Leroy Leo in Bengaluru; Editing by Nancy Lapid and Nick Zieminski)