CHICAGO (Reuters) - Avandia, GlaxoSmithKline Plc’s widely used drug for treating type 2 diabetes, increased the risk of heart death by 64 percent and the risk of heart attack by 43 percent, U.S. researchers said on Monday.
The news about Avandia, also known as rosiglitazone, triggered a freefall in GSK’s shares, which closed off more than 5 percent on the London Stock Exchange. The stock slide continued on the New York Stock Exchange, falling $3.67 per share, or more than 6 percent.
Glaxo said it strongly disagreed with the conclusions of the report, which was based on an analysis of other studies.
“Unfortunately, rosiglitazone appears to increase, rather than decrease, the most serious complication of diabetes, heart disease,” Dr. Steven Nissen, chairman of cardiovascular Medicine at the Cleveland Clinic, said in a statement.
Writing in the New England Journal of Medicine, Nissen and colleagues at the Cleveland Clinic analyzed 42 clinical trials involving close to 28,000 patients and said more than 65 percent of the deaths among diabetic patients in the trials of the drug could be attributed to heart disease.
“Unless this can be refuted, which I rather doubt, then this is going to seriously damage one of the cornerstones of Glaxo going forward,” said Paul Diggle, an industry analyst at Nomura Code Securities in London.
But Glaxo disagreed. “GSK stands firmly behind the safety of Avandia when used appropriately, and we believe its significant benefits continue to outweigh any treatment risks,” the company said in a statement.
In a commentary accompanying the study, Dr. Bruce Psaty of the University of Washington and Dr. Curt Furberg of Wake Forest University called for U.S. regulators to take action, saying, “...the rationale for prescribing rosiglitazone at this time is unclear.”
“Unless new data provide a different picture of the risk-benefit profile, regulatory action by the Food and Drug Administration is now warranted,” they wrote.
Avandia was approved by the FDA in 1999 to help patients with diabetes keep blood sugar levels within safe limits. Since then, 60 million prescriptions have been written for the drug, the researchers said. It has annual sales worth $3 billion.
The findings are based on analysis of published data from clinical trials that compared the risk of heart attack and heart disease-related death in patients on Avandia with patients who took a placebo or other diabetes drugs.
“The results of this analysis raise serious concerns about the cardiovascular safety of rosiglitazone,” Nissen said in a statement.
He said the study was limited because it did not include access to original data, which would have shown how long it took for patients to have a heart-related problem.
Nevertheless, he said the analysis raised a red flag.
“Patients and providers should consider the potential for serious adverse cardiovascular effects of treatment with rosiglitazone for type 2 diabetes,” Nissen said.
Diabetes is caused by high levels of blood sugar or glucose when the body experiences defects in the production of insulin, or in the way cells use insulin. This in turn allows too much glucose to enter the body’s cells.
Patients with diabetes are at higher risk of heart disease, kidney failure, nerve damage, blindness and other eye diseases.
In February, GlaxoSmithKline warned U.S. doctors that the drug increased the risk of bone fractures in the feet and upper limbs.
Avandia competes with Merck & Co. Inc.’s Januvia, the first in a new class of diabetes drugs that the U.S. company has already been promoting as superior to Avandia, and with Actos, a drug made by Japan’s Takeda Pharmaceutical Co Ltd..
Nearly 21 million people in the United States have diabetes, according to the U.S. Centers for Disease Control and Prevention, with type 2 diabetes accounting for up to 95 percent of the cases.
Additional reporting by Ben Hirschler in London