10/24/2007- The Food and Drug Administration wants GlaxoSmithKline PLC to add the strongest form of safety warning about heart-attack risk to the label of its diabetes drug Avandia, according to people with knowledge of the matter, a move that would compound the commercial woes of the once-popular medication.

Agency officials are pushing for a "black box" warning, these people say. The new label is still being discussed with the company and its final form isn't yet clear. In high-profile safety matters, the agency tends to have strong leverage.

The new warning would be a blow to GlaxoSmithKline, which had said there isn't clear evidence Avandia is more dangerous than competitors. Avandia already carries a black-box warning about a different side effect -- heart failure -- but a heart-attack warning would be more serious. Avandia's main rival drug, Takeda Pharmaceutical Co.'s Actos, carries a heart-failure caution, but doesn't have one for heart-attack risk.

An FDA spokeswoman said the agency "is still involved in internal discussions on this matter" and that when there is a final decision it will become public. A GlaxoSmithKline 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 new label warning would represent the latest reversal for Avandia, Glaxo's second biggest-selling drug last year, with global sales of $3.38 billion, or 7% of the United Kingdom company's total sales. Avandia's prescriptions plunged after a medical journal article by Cleveland Clinic cardiologist Steven Nissen in May raised concerns about its possible heart risk.

If it goes into effect, the new warning would focus on Avandia's potential for increased ischemic risk: a risk of events in which blood is choked off from the heart. 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 company has said 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 U.S. because of the potential heart danger. A committee of FDA advisers, though, voted that it should remain on the market, even though the panel said the drug was tied to increased ischemic risk.

Avandia's woes would likely benefit Actos. Doctors may also look at older medications such as metformin and newer options such as Merck & Co.'s Januvia.

The potential Avandia label-change has played out amid pressure from outside researchers and scrutiny from Capitol Hill. In June, there was a congressional hearing focused on the drug's safety, and the FDA's handling of it. The drug is the subject of continuing investigations by lawmakers.

Separately, Glaxo and Mylan Inc. yesterday agreed to settle a patent dispute over the antidepressant Paxil CR. As part of the deal, Mylan, a U.S. maker of generics, will have the right to market its version of Glaxo's drug, generically known as paroxetine hydrochloride, beginning no later than Oct. 1, 2008.