The FDA scheduled a Monday meeting to ask drug safety and diabetes experts to review GlaxoSmithKline's blockbuster drug after a medical journal article in May suggested heart attack risk in patients who take the drug is 43 percent higher.
The agency posted documents Thursday on its Web site that include its latest review of the drug.
Until now, the FDA has maintained that safety data on the blockbuster diabetes drug is inconclusive — but not anymore, reports CBS News correspondent Nancy Cordes.
In a new report, FDA reviewers warn, "current available information points to an increased risk of cardiovascular effects, including heart failure… and cardiovascular death in diabetic patients."
FDA is also expected to ask panelists whether any heart attack risks seen with Avandia are greater than those of rival diabetes treatments, which include Takeda Pharmaceutical's Actos and Merck & Co.'s Januvia.
The agency is not required to follow the recommendation of the panel of experts although it usually does. The company says its studies show that the drug is as safe as comparable treatments.
However, FDA revealed in its review that Glaxo approached the agency last summer about adding heart-attack risk language to the product's label. The warning would have noted that increased rates of heart attack occurred in some company studies, while saying that it was not clear whether they were connected to Avandia.
FDA rejected the proposal, arguing that any information about heart-attack risk should appear in a more prominent "black box" warning, the most serious warning a drug can carry.
The FDA said panelists should weigh Avandia's potential risks against its benefits.
More than 6 million people worldwide have taken Avandia or a related drug, Avandamet, since it came on the market in 1999. Doctors use the pills to control blood sugar levels in patients with adult-onset diabetes.
In briefing documents posted online Thursday, Glaxo argued that "there is no consistent or systematic evidence" linking Avandia to increased risk of heart attack or death. However, the company recommends expanding the drug's label, which already includes a warning about heart failure, a condition in which the heart cannot effectively pump blood to the body.
Glaxo said it plans to add a warning that diabetics who already take insulin should not take Avandia. The proposed warning is consistent with the FDA's review, which found insulin-taking patients who also use Avandia face a greater risk of heart failure. Reviewers did not see the same risk in studies of Takeda's Actos, a drug closely-related to Avandia.
Federal lawmakers and consumer groups are pressuring regulators to put further restrictions on Avandia's use. But the agency said it wants to hear from outside experts before recommending any changes.
Cordes reports that if the FDA does take action on Avandia, it will have some explaining to do about why it initially downplayed concerns about the drug.
The British drug maker reported Wednesday that U.S. sales of Avandia fell 31 percent to $226 million in the quarter since safety concerns emerged. Glaxo reported total U.S. sales of $2.2 billion for the drug last year.