UPDATE 1-U.S. senator asks FDA about internal Avandia vote

(Adds details on panel; Glaxo, Public Citizen comments in paragraphs 10-16)

By Kim Dixon

WASHINGTON, Oct 29 (Reuters) - A senior Republican lawmaker asked the U.S. Food and Drug Administration to confirm that an internal FDA group privately voted to keep the troubled diabetes drug Avandia on the market by a one-vote margin, according to a letter made public on Monday.

Sen. Charles Grassley, the ranking Republican on the Senate Finance Committee, said committee investigators learned that the FDA's Drug Safety Oversight Board (DSOB) voted 8-7 on Oct. 2 to keep the GlaxoSmithKline (GSK.L: Quote, Profile, Research, Stock Buzz) drug on the market.

The FDA set up the internal board in 2005 after a series of controversies, including criticism over the recall of Merck's (MRK.N: Quote, Profile, Research, Stock Buzz) painkiller Vioxx, put pressure on the agency to bolster its systems for tracking drug safety.

The board is made up largely of director-level FDA officials and meetings are not open to the public. Meeting summaries are posted on the agency's Web site, but the last one is dated Aug. 22.

The FDA is considering stronger warnings to Avandia's label after an agency advisory panel in July voted 22-1 to keep Avandia on the market, even though it may raise heart-attack risks. Most members of that panel also advised the FDA to add new warnings about that risk.

The July meeting was prompted by an analysis published in the New England Journal of Medicine that linked the drug to a 43 percent boost in heart attack risk. "The Avandia case continues to present new rounds of questions about the way the FDA monitors and assesses drug risks and decides whether to let the public know about emerging risks," Grassley said in a statement.