Glaxo’s diabetes pill already has such a warning about heart failure, but apparently the FDA wants to add one about the risk of heart attacks, according to The Wall Street Journal. Talks are still under way, the paper writes, but if agency officials succeed, the move would make it still more difficult for sales to rebound.

Ever since the New England Journal of Medicine published a study last May that Avandia raised the risk of heart attacks by 43 percent, the drugmaker has insisted evidence is lacking that the diabetes pill is more dangerous than rival meds. Avandia scrips, meanwhile, have continued to plunge and sales were down 38 percent in the third quarter. As the paper notes, Takeda’s Actos also carries a warning about the risk of heart failure, but not heart attack.

An FDA spokeswoman tells the paper that the agency “is still involved in internal discussions on this matter” and that when there is a final decision it will become public. Similarly, a Glaxo spokeswoman said the company is “working diligently with the FDA to finalize the label, but it would be inappropriate for us to discuss the ongoing conversations with the agency.”

The additional warning would focus on the potential for increased ischemic risk - an FDA analysis that crunched together multiple Avandia studies found that the drug appeared to be linked to a 38% higher risk of ischemic events, the Journal writes. The drugmaker has argued that such analyses aren’t typically considered the strongest form of medical evidence, and that other data didn’t show a similar risk.

A black-box warning would still represent something of a middle ground in the debate over Avandia. During a public meeting in July, some FDA officials said the drug should no longer be sold in the US because of the potential heart danger. Still, an FDA panel voted that Avandia should remain on the market, because the benefits outweighed the risks.

Avandia’s woes would likely benefit Actos, the Journal notes, but Avandia’s troubles may not end - the drug is the subject of continuing investigations by lawmakers.