In a statement issued late Tuesday, the company fired back at editorials recently published in the New England Journal of Medicine that accompanied a meta-analysis that cast doubt on Avandia's heart safety.

"We believe the NEJM editorials are selective in their use of data to support a biased view, and therefore do a disservice to patients, physicians, science and public health," Glaxo said.

The company said the meta-analysis -- authored by Cleveland Clinic cardiologist Steven Nissen -- does not allow a conclusion regarding heart attack risk, "yet the editorials largely ignore this point, and seem to assume this risk is self-evident."

Glaxo this week released interim data from its own RECORD study -- designed to assess Avandia's heart attack risk and set for completion in 2008 -- that it said contradicts Nissen's hypothesis suggesting a 64-percent increase in cardiovascular deaths.

Instead, RECORD shows a 17 percent decrease in that risk, the company argued.

Glaxo also accused the NEJM editors of glossing over RECORD data showing no increase in all-cause mortality, and no rise in the so-called MACE endpoint, comprised of cardiovascular mortality, myocardial infarction and stroke. "These endpoints are very relevant for patients and their physicians," the drug maker said.

Glaxo's defense of its blockbuster drug comes as Congress prepares to hold a hearing on Avandia's safety in light of the new data. The Food and Drug Administration is also slated to meet with an advisory panel July 30 on the issue.