Glaxo Defends Safety of Weight Loss Drug Alli

British drugmaker GlaxoSmithKline is scrambling to shore up the safety image of its weight loss pill alli, after watching sales dive on news that federal regulators are investigating the drug.

Alli has received a high-profile marketing push as the first over-the-counter weight loss medication, complete with television ads and a celebrity endorsement from country singer Wynonna Judd.

However, Glaxo has spent the last two weeks on damage control after the Food and Drug Administration said it was probing more than 30 reports of liver damage in patients taking alli and Xenical, the prescription version of the drug.

Glaxo executives say sales of alli dropped 10 percent after the Aug. 24 announcement, even though the FDA stressed it had established no direct link between the drug and liver problems.

Glaxo rushed out print advertisements in national newspapers and magazines, stressing the extensive safety testing behind the drug.

"It's the most widely studied weight loss medicine ever, with over 100 clinical studies involving 30,000 patients," Howard Marsh, chief medical officer of Glaxo's consumer products division, said in an interview.

U.S. sales of alli climbed 12 percent from a year ago to $42 million in the last quarter, though they have come nowhere near the blockbuster numbers originally expected by Wall Street after the drug's 2007 launch. Analysts say the brand has been hurt by lower consumer spending as well as unpleasant side effects, such as anal leakage.

The latest marketing push has been fairly aggressive, though it may be needed to protect a brand that has been buffeted by negative publicity, said John Mack, editor and publisher of Pharma Marketing News.

"I think they're very concerned about all the side effects that are being thrown against the product, whether they're real, potential or imaginary," said Mack. "There's been a lot of talk about all those things and they don't seem to be able to get out from under them."