US officials have slapped a warning of an increased risk of heart attacks on an anti-diabetes drug manufactured by the British company GlaxoSmithKline.
The manufacturers of Avandia have "agreed to add new information to the existing boxed warning in the drug's labeling about potential increased risk for heart attacks," the FDA said in a statement Wednesday.
Patients suffering type 2 diabetes with underlying heart disease or at risk of heart attack should talk to their doctors before taking the drug, the FDA warned.
Four clinical trials of more than 14,000 patients showed that Avandia taken over a prolonged period increased the risk of cardiovascular problems by some 42 percent, according to a study published in September.
The study in the Journal of the American Medical Association was the first to examine the risks of heart problems and death stemming from the use of Avandia by type 2 diabetes sufferers who had been taking the drug for at least a year.
The drug is taken by some seven million people around the world, half of them in the United States, and brings in some 3.3 billion dollars for Glaxo in annual global sales.
An analysis of some 42 short-term clinical studies published in May in the New England Journal of Medicine had already concluded that Avandia increased the risk of heart attacks by 43 percent.
But a committee of independent experts consulted by the FDA decided in July that the risks did not warrant withdrawing the drug from the market.