A diabetes drug prescribed to Canadians nearly 1.3 million times over the past year more than doubles the risk of heart failure, a new analysis shows.Researchers estimate there would be one additional case of heart failure -- where the heart cannot pump enough blood through the body -- for every 30 diabetic patients taking GlaxoSmithKline's Avandia for one year.As well, for every 220 diabetics treated with the drug for at least 12 months, one additional person would suffer a heart attack, according to the study published in this week's Journal of the American Medical Association."The public health impact of substantial harm associated with rosiglitazone (Avandia's chemical name) is substantial," the researchers write.They say doctors should not wait for regulatory action and should avoid using the drug in diabetics at risk of heart problems.It is the latest run of bad news for a drug already linked, in rare cases, with new or worsening vision problems and increased bone fractures in women.In May, a study published in the New England Journal of Medicine warned of a 43% increased risk of heart attack and a 64% increased risk of death by heart attack in patients on Avandia. That study focused on short-term use and included patients with dementia or psoriasis.The new study looks only at people with Type 2 diabetes or impaired glucose tolerance and who took the drug for at least 12 months in studies that checked for effects on the heart.

"My view is, we don't need it," says Dr. Curt Furberg, a co-author of the new study."If you add up the bad news about Avandia -- doubling the risk of heart failure, doubling the risk of fractures in women, 40% increase in heart attacks and then, in some cases, blindness -- on the one side, on the good side the only thing they [the drug company] claims is [Avandia] reduces blood glucose level," said Dr. Furberg, who is a professor of public health sciences at Wake Forest University School of Medicine.GlaxoSmithKline says the new study uses "highly selective data" from only four of 116 available studies and that it conflicts with analyzed studies that show no difference in heart effects of Avandia versus other anti-diabetes medicines, including other drugs in its class."The authors have made sweeping, unsupported statements about Avandia that are potentially damaging to patients," says Dr. Ravinder Kumar, vice-president of regulatory and development operations.In July, a U.S. Food and Drug Administration advisory committee said Avandia should remain on the market.As of April 30, Health Canada had received 243 reports of adverse cardiovascular-related reactions for rosiglitazone, 31 of them for heart attacks. There were 19 reports of heart-related deaths, including fatal heart attacks and heart failure.In 10 cases, there was not enough information available to prove a cause-and-effect link. In two cases, death was unlikely caused by the drug, a preliminary review found. But in the remaining seven, a possible link between the drug and the death was cited.