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CHICAGO - Avandia, GlaxoSmithKline Plc's widely used drug for treating type 2 diabetes, raises the risk of heart death by 64 per cent and the risk of heart attack by 43 per cent, US researchers have said.
The news about Avandia, a US$3 billion ($4.1 billion) a year
drug also known as rosiglitazone, triggered a free fall in GSK's shares, which closed off more than 5 per cent on the London Stock Exchange. The slide continued on the New York Stock Exchange, with shares closing down nearly 8 per cent.
Glaxo said it strongly disagreed with the conclusions of the report, 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.
"The whole reason you want to treat diabetes is to prevent the complications of diabetes," Nissen added in a telephone interview.
Writing in the New England Journal of Medicine, Nissen and colleagues said they analysed 42 clinical trials involving close to 28,000 patients and said more than 65 per cent of the deaths among diabetic patients in the trials of the drug could be attributed to heart disease.
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.
Drs. Bruce Psaty of the University of Washington and Curt Furberg of Wake Forest University, in an accompanying commentary, said the case shows that stronger drug-safety legislation is needed.
"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.
The report by one of the leading US cardiologists caught the eye of lawmakers, adding new pressure on the FDA to beef up surveillance of drugs once they reach the market.
One congressional committee scheduled a hearing on the drug's safety.
"Both the drug company and the FDA have some major explaining to do about what they knew about Avandia, when they knew it, and why they didn't take immediate action to protect patients," said Sen. Max Baucus, a Montana Democrat who chairs the Senate Finance Committee.
Dr. Robert Meyer, head of the FDA office that reviews diabetes drugs, said other data contradicted those findings about the risks of Avandia, for which some 60 million prescriptions have been written.
"Further, the FDA does not know whether the other approved treatments in the same class of drugs ... have less, the same, or other greater such risks," Meyer told reporters.
Nissen said his 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.
About 21 million people in the United States have diabetes, with 95 per cent having type 2 diabetes, which raises the risk of heart disease, kidney failure and other serious complications.
Avandia and Actos, a drug made by Japan's Takeda Pharmaceutical Co. Ltd., are part of a class of drugs known as thiazolidinediones or glitazones.
The first drug in the class, Rezulin, was pulled from the market in March 2000 after about 63 people who took it died from acute liver failure.
Another study in 2003 suggested that Avandia might cause heart failure, and Glaxo warned doctors in February that Avandia increased the risk of bone fractures.
Avandia competes with Merck & Co. Inc.'s Januvia, the first in a new class of diabetes drugs. Merck's shares rose US$1 or nearly 2 per cent on Monday.
- REUTERS
