The U.S. Food and Drug Administration announced on August 16th that manufacturers of certain drugs approved to treat Type 2 diabetes have agreed to add a stronger warning on the risk of heart failure.

The information will be included in the form of a "boxed" warning-FDA's strongest form of a warning. The upgraded warning emphasizes that the the entire thiazolidinedione class of antidiabetic drugs.may cause or worsen heart failure in certain patients.

This class includes Avandia (rosiglitazone), Actos (pioglitazone), Avandaryl (rosiglitazone and glimepiride), Avandamet (rosiglitazone and metformin), and Duetact (pioglitazone and glimepride).

These drugs are used in conjunction with diet and exercise, to improve blood sugar control in adults with type 2 (non-insulin-dependent) diabetes.

"Under FDA's postmarketing surveillance program, we carefully monitor new safety information for marketed drugs and take appropriate action when necessary to inform patients and health care providers of new information," said Dr. Steven Galson, director of FDA's Center for Drug Evaluation and Research.

"This new boxed warning addresses FDA's concerns that despite the warnings and information already listed in the drug labels, these drugs are still being prescribed to patients without careful monitoring for signs of heart failure," Galson said.

FDA's review of adverse event reports found cases of significant weight gain and edema-warning signs of heart failure.

The strengthened warning advises health care professionals to observe patients carefully for the signs and symptoms of heart failure, including excessive, rapid weight gain, shortness of breath, and edema after starting drug therapy.

FDA's review of Avandia and possible increased risk of heart attacks is ongoing.

On July 30, 2007, FDA's Endocrine and Metabolic Advisory Committee and the Drug Safety and Risk Management Advisory Committee recommended that Avandia continue to be marketed, and further recommended that information be added to the labeling for risk of heart attacks (ischemic risks).