Canadian researchers furnished the strongest evidence to date linking the popular diabetes drug Avandia to an increased risk of heart attack in a scientific study released yesterday.
Compared with other diabetes pills, Avandia’s use was associated with a 60 percent higher risk of heart failure, 40 percent higher risk of heart attack and 30 percent higher risk of death in patients 65 and older, the researchers found.
"The risks associated with these drugs may outweigh the benefits, at least for older populations," said Dr. Lorraine L. Lipscombe, the lead author of the study and a researcher at a health research agency funded by the Ontario government.
The findings, published in the influential Journal of the American Medical Association, will probably intensify pressure on the government to restrict sales of the oral diabetes medicine.
"It should come off the market," said Dr. Sidney M. Wolfe, director of health research at Public Citizen, a liberal interest group preparing to petition the Food and Drug Administration to pull the drug.
Sales of Avandia have plummeted since Dr. Steven Nissen, a prominent cardiologist, reported in May that it raised the risk of heart attack. His report prompted congressional hearings and demands to stop sales.
The FDA decided against that last month, instead adding a label warning that urges users to consult a doctor if they have serious heart problems.
The decision divided agency staff. Ultimately, FDA officials decided the scientific evidence wasn’t conclusive, and they asked Avandia’s manufacturer to conduct a long-term study.
In a statement, the FDA said it would review the results from the Canadian study, but it needs more evidence before taking any further action. "This new study we have just seen today does not change FDA’s recommendations," the agency said.
GlaxoSmithKline, Avandia’s maker, dismissed the Canadians’ findings as limited and misleading because the elderly studied might have been at higher risk of heart problems.
The Philadelphia company, which is conducting a long-term study of Avandia’s side effects, said in a statement that many other studies show Avandia is safe and effective.
The new study is the first to review side effects in real patients, rather than test subjects, according to Lipscombe, a researcher at the Institute for Clinical Evaluative Sciences in Toronto.
Beginning in March, Lipscombe and her colleagues analyzed health care records for all elderly Ontario residents who took an oral diabetes medicine between 2002 and 2006.
Lipscombe said they focused on the elderly because 40 percent of diabetes patients in Ontario are 65 and older, but the elderly tend to be underrepresented in scientific drug studies.
The researchers didn’t find a higher heart risk among users of Actos, an Avandia competitor that belongs to the same class of diabetes drugs, but Lipscombe said there weren’t enough Actos users to draw a firm conclusion.