Millions of Americans taking the highly promoted diabetes drug Avandia could be putting themselves at risk for deadly heart problems, according to new research.
The findings are the latest volley in a spate of criticism over the U.S. Food and Drug Administration's drug approval and regulation procedures.
The new concerns surfaced Monday in a review of previous research published in the New England Journal of Medicine.
The analysis revealed that those taking the widely used drug experienced a 43 percent higher risk of heart attacks and a 64 percent increased risk of dying from heart disease
Lead author of the analysis and president of the American College of Cardiology, Dr. Steven Nissen, told ABC News medical correspondent John McKenzie, in an interview for "World News" that the findings are "alarming."
"It needs to be confirmed with other analyses, but if the data hold up — and I believe that they will hold up — it does represent a huge public health concern," he said.
The review of data encompassed 42 clinical trials, involving a total of 27,000 diabetic patients.
Some doctors worry that this further demonstrates how risks associated with many drugs may slip through the cracks when it comes to approvals.
"Both the FDA and the drug company presumably had this data in hand," Dr. David Nathan, director of the diabetes center at Massachusetts General Hospital told McKenzie. "So why didn't they ever look at it the same way Dr. Nissen and his colleagues did?"
Dr. Christopher Cannon, a cardiologist at Brigham and Women's Hospital in Boston, agrees. "As [Nissen] notes in his paper, they have access to all these data, so why did they not find this?"
In a conference call Monday afternoon, Dr. Robert Meyer of the FDA's Office of Drug Evaluation II, Center for Drug Evaluation and Research, said that it has had the heart attack data since August of last year.
"We decided that we needed to reanalyze the complex data set ourselves to make a better informed decision about what the meaning of those data might be," he said.
In an accompanying commentary, Dr. Bruce Psaty of the University of Washington and Dr. Curt Furberg of Wake Forest University said regulators must take action.
"The rationale for prescribing [Avandia] at this time is unclear," the editorial reads. "Unless new data provide a different picture of the risk-benefit profile, regulatory action by the Food and Drug Administration is now warranted."
The drug, manufactured by GlaxoSmithKline is intended to help patients with diabetes control their blood sugar levels.
Since its approval by the FDA in 1999, more than 6 million people worldwide have taken Avandia.
In total, 60 million prescriptions have been written for the drug, and it generates annual sales worth $3 billion annually.
Despite the review, the FDA is not asking GlaxoSmithKline to take any specific action at this time. And there are no plans yet to strengthen warnings on the product's labeling, which already include risks to the heart.
In fact, the most recent labeling change for Avandia in 2006 included a new warning about a potential increase in heart attacks and heart-related chest pain in some individuals using the drug.