Avandia has been hit with new restrictions by Canadian regulatory authorities following reports that the controversial diabetes drug puts patients at a higher risk for heart attacks and other cardiac problems. The new Canadian Avandia restrictions will no doubt further weaken sales of the medication, which had already fallen 60% since questions about the drug’s safety were first raised.
The new Avandia restrictions were requested by Health Canada, the agency which regulates drugs in that country. Health Canada said that its request was prompted by reports of adverse events linked to Avandia, as well as published studies that indicated it put users at an increased risk for heart problems. Those studies included one published in May by the Cleveland Clinic that showed that patients taking Avandia had a 43-percent higher risk of having a heart attack.
GlaxoSmithKline, the manufacturer of Avandia, sent a letter to Canadian health professionals informing them that Avandia can no longer be prescribed as monotherapy for type 2 diabetes, except when metformin use is contraindicated or not tolerated. Health Canada has also withdrawn its approval for Avandia to be used in combination with a sulfonylurea, except when metformin is contraindicated or not tolerated. Finally, the letter said that treatment with Avandia is now is now contraindicated in patients with any stage of heart failure.
Health Canada is only the latest regulatory agency to restrict Avandia usage. Last month, the United States Department of Veterans Affairs (VA) announced that it was dropping Avandia from its prescription drug formulary. In a statement announcing the move, the VA said that it had conducted its own review and concluded that, for some patients, Avandia did not afford the same margin of safety as other diabetes medications. The VA said that it would still make Avandia available for patients who were currently taking it and wanted to continue. However, the VA urged doctors to discuss Avandia’s safety issues with these patients. But the decision means that patients not currently prescribed Avandia will not be able to get it through the VA in the future. Prior to its announcement, the VA accounted for about 8% of Avandia’s sales in the United States.
In July, the Food & Drug Administration (FDA) convened a panel to discuss the issues surrounding Avandia’s heart attack risk. The panel voted 20-3 that the drug did in fact raise the chance of heart attacks, yet the panel still voted 22-1 to allow it to remain on the market. The advisory panel did recommend that stronger heart attack warnings be added to the Avandia label, and the FDA is currently working with GlaxoSmithKline to develop a black box warning for Avandia regarding heart attack risks.