People who take the widely used diabetes drug Avandia may be putting themselves at higher risk of developing fatal heart problems, according to two large studies published today in the Journal of the American Medical Association.
The first study analyzed 56 studies totalling more than 35,000 patients that compared Avandia to other drugs used to lower blood sugar in patients with diabetes. Patients taking Avandia were 33 percent more likely to have a heart attack compared to those on other treatments, according to the study.
The second study, by Dr. David Graham, associate director of the Food and Drug Administration, analyzed data collected from more than 220,000 elderly patients in a Medicare health insurance program who either took Avandia or its equivalent class drug Actos. While the study found an increased risk of heart failure, stroke and death among patients taking Avandia compared to those taking Actos, there was no difference in risk of heart attack among those taking Avandia and Actos.
"There is no reason for this drug to be given to patients," said Dr. Steven Nissen, chairman of cardiovascular medicine at the Cleveland Clinic, and author of the first study.
Watch ABC News' senior health and medical editor Dr. Richard Besser's report on Avandia tonight at 6:30 p.m. ET on "World News With Diane Sawyer"
These studies are not the first to question Avandia's safety. GlaxoSmithKline first reported the results of its review -- which found an increased risk of heart attacks in Avandia patients -- to the FDA in 2005, but neither the company nor the federal agency issued a public warning at the time.
A 2007 study conducted by Nissen first raised public concern about Avandia's cardiovascular effects. The FDA decided in November 2007 to leave the drug on the market, with the addition of a black box warning of the risk of heart attack.
Since then, the popular diabetes drug lost more than half of its sales, although it still generated more than $1 billion in revenue last year alone.
Nissen said his latest study, the largest to date analyzing the potential adverse effects of Avandia, confirmed his previous findings. Still, dueling reports have gone back and forth on whether the cardiovascular risk associated with Avandia is real.
These studies come just weeks before a July 13 FDA advisory committee panel to review the safety of Avandia, developed by GlaxoSmithKline. The panel's recommendations could include keeping the drug on the market, calling for further restrictions or pulling it altogether.
The consumer watchdog group Public Citizen took the new analyses as an opportunity to push for the FDA to stop marketing Avandia.
"Every month that the FDA fails to get the drug withdrawn from the market means that an additional 150,000 to 200,000 prescriptions will be filled in this country, needlessly exposing people to the increased risk of stroke, heart failure and heart attacks," Dr. Sidney M. Wolfe, director of Public Citizen's health research group, said in an e-mail.
According to Nissen, the challenge to pull the drug off the market lies in bridging the so-called internal conflict between the FDA's drug approval committee, and the committee that reviews safety. The authority rests with those who approve medications, said Nissen.
"Historically, it's hard to get drugs off the market once it's been successfully marketed," said Nissen.