The New England Journal of Medicine recently featured an article, written by Dr. Steven Nissen, about the diabetes drug Avandia. Its conclusions, about side effects such as heart problems and heart attacks, were worrisome enough to merit an accompanying editorial. In it, Drs. Bruce Psaty and Curt Furberg determined that “the rationale for prescribing rosiglitazone [Avandia] at this time is unclear.”

The two doctors contend—along with Dr. Nissen—that Avandia’s risks outweigh its benefits and call upon the Food and Drug Administration to take action in the form of a “black-box” warning or even a recall. A mainstay for many type 2 diabetics since going on the market in 1999, Avandia is quite popular; more than 60 million prescriptions have been written for the drug en toto. Sales last year exceeded $3 billion.

The well-being of GlaxoSmithKline, which makes and markets Avandia, was hurt by the publication of the NEJM study and editorial. Its stock price dropped 7.85%, and 11 million shares (nine times the usual trading volume) changed hands. The company soon went on the offensive, slamming Dr. Nissen’s research methods and conclusions.

A GSK spokesperson asserts correctly that Dr. Nissen’s study was a meta-analysis (that is, a study of other studies), not a direct observation of patients. Nevertheless, GSK did its own meta-analysis of Avandia patients, finding a 31% greater risk of heart attack than those in a control group.

Less than a day after the publication of Dr. Nissen’s study and the editorial by Drs, Psaty and Furberg, the FDA put out an Avandia safety alert. The agency plans to convene an advisory committee to look at the heart risks of Avandia. Earlier data about Avandia had caused the FDA to strengthen its warning label last year.