Meyer defended the regulatory body's actions on Avandia. "We don't have clear regulatory or clinical advice message as of today," he said, adding that the FDA is "also in possession of unpublished and published data that could lead to quite a different conclusion."
Meyer added that the FDA is very close to completing its own meta-analysis on the drug.
GlaxoSmithKline stood behind the safety of its drug in its own statement issued Monday, maintaining that its benefits outweigh any possible risks.
"GSK strongly disagrees with the conclusions reached in the NEJM article, which are based on incomplete evidence and a methodology that the author admits has significant limitations," the statement reads.
Still, physicians say the article and its accompanying editorial provide compelling evidence that more review is needed for the drug.
"In over 40 years of reading NEJM editorials, this is as strong — in criticism of the FDA and using lab measurements instead of clinical outcomes for approval — as I have ever read," says ABC News medical editor Dr. Timothy Johnson. "The writers clearly believe that the current approval process and post approval surveillance are not adequate."
Dr. Sidney Wolfe, director of the health research group for the consumer organization Public Citizen, said in a statement issued Monday that the drug should be considered too dangerous for use.
"[W]ithin the first six years of approval, there have been 689 cases of heart failure reported to the FDA in patients using the drug," Wolfe said.
"Despite prior knowledge of serious cardiac problems, the FDA has failed to require Glaxo to adequately warn about the dangers of this drug that should be, at best, a last-choice treatment for Type II diabetes. … We strongly urge patients — as we have for almost two and a half years — not to use this drug."
Others says the new evidence signals the need for more stringent approval guidelines in general.
Dr. Susan Louisa Montauk, professor of clinical family medicine at the University of Cincinnati College of Medicine, says that if the FDA is not more vigilant in its approval process, "[W]e will have dozens of Avandias every year very soon ... drugs we are confused about that may save some lives and shorten others."
The analysis has already prompted Rep. Henry Waxman, chairman of the House Committee on Oversight and Government Reform, to announce a hearing for June 6, 2007, on the FDA's role in evaluating Avandia's safety.
As for now, FDA's Meyer says the strongest action that patients on the drug should take is to talk to their doctors about potential risks, especially if they have a history of heart problems.
ABC News medical correspondents John McKenzie and Brian Hartman contributed to this report.