A diabetes drug may dramatically increase the risk of heart attacks, said a study released Monday, prompting a US government safety alert, which was rejected by GlaxoSmithKline.
Rosiglitazone, sold under the name Avandia by British pharmaceutical giant GlaxoSmithKline, was linked to a "significant risk" of heart attacks and death from cardiovascular causes based on an analysis of dozens of clinical trials, said the study published on the New England Journal of Medicine's website.
While the study is not conclusive and more research is needed, the scientists wrote, the findings "are worrisome because of the high incidence of cardiovascular events in patients with diabetes."
The US Food and Drug Administration (FDA) said in a statement Monday it was "aware of a potential safety issue related to Avandia" and advised patients taking the drug to speak to their doctors in light of the new study.
The federal agency said it was still studying the effects of the drug and took no immediate action.
"In this case, FDA is carefully weighing several complex sources of data, some of which show conflicting results, related to the risk of heart attack and heart-related deaths in patients treated with Avandia," said Steven Galson, director of the agency's Center for Drug Evaluation and Research.
"We will complete our analyses and make the results available as soon as possible," Galson said in a statement.
An editorial accompanying the study urged the FDA to review the use of the drug and said the study -- if correct -- raised serious questions about how new medical drugs are approved and regulated after entering the market.
Evidence of the drug's benefits was "at best mixed" when it was originally approved for use by FDA, said the editorial authored by two doctors, Bruce Psaty of the University of Washington in Seattle and Curt Furberg of Wake Forest University.
"In view of the potential cardiovascular risks and in the absence of evidence of other health advantages, except for laboratory measures of glycemic control, the rationale for prescribing rosiglitazone at this time is unclear," the editorial said.
It also called on GlaxoSmithKline to make more data publicly available about the results of previous clinical trials.
But the British company rejected the study's findings and said it had shared data consistently with federal regulators.
"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.
The firm said it "strongly disagrees" with the study's conclusions "which are based on incomplete evidence and a methodology that the author admits has significant limitations."
The British company's stock declined on Monday, with the share price down 7.8 percent to close at 53.18.
Avandia was introduced in 1999 and is widely used to treat type-2 or adult-onset diabetes, which has surged in the United States owing to an epidemic of obesity. Some 18 to 20 million Americans have type-2 diabetes.
