The Food and Drug Administration has ordered

Pfizer

(PFE) - Get Report

to pull two television ads promoting the impotence treatment Viagra because the agency said the ads don't provide information about the drug's potential side-effects.

Daniel Watts, a spokesman for Pfizer, said the company will pull the ads. At some point, he added, Pfizer will run new TV ads, but he didn't provide a timetable.

The FDA's criticism is based on the regulations that allow companies to tout a product's benefits as long as they inform patients about a drug's side-effects. That's easy to do in a newspaper or magazine ad; it's tougher in a 15-second or 30-second TV commercial.

The agency, which wrote Pfizer on Nov. 10 and released a copy Monday, told the company that a 15-second and 30-second TV ad nicknamed "Wild Thing" failed to meet the guidelines.

In the ad, an announcer asks, "Remember the one who couldn't resist a little mischief?" The ad also shows the man with what appear to be horns emerging from his head. As the man moves, the viewer sees that the horns are the top of the letter V.

The ads "make clear that Viagra is intended for sex," the FDA's letter said. But the ads don't include warnings about possible side-effects -- including cardiovascular risk and the rare prospect of four-hour erections, or the fact that the drug doesn't protect against sexually transmitted diseases, the FDA said.

The ads suggest that Viagra "will provide a return to a previous level of sexual activity and desire," the FDA said. The agency said it is "not aware of substantial evidence or substantial clinical experience demonstrating this benefit" for Viagra patients. "If you have data substantiating this claim, please submit them to FDA for review," the agency's letter said.

Pfizer and other drug companies have run ads for many drugs that simply identify the name of a drug and say something like "See Your Doctor." If the ads don't describe what the drug does, then companies don't need to include information about side-effects.

But if they are more descriptive in their TV advertising by telling what the drugs do and suggest how well they do them, then companies must provide information on side-effects. The makers of Cialis and Levitra, the two competitors for Viagra in the impotence treatment market, have used such descriptive ads. Cialis is marketed by

Icos

(ICOS)

and

Eli Lilly

(LLY) - Get Report

. Levitra is marketed by

GlaxoSmithKline

(GSK) - Get Report

and

Bayer

(BAY)

.

Pfizer's "Wild Thing" ads crossed the line, providing enough innuendo about its use without alerting users to its potential drawbacks. The ads are part of Pfizer's efforts to combat competition. For more than five years, Viagra was the only FDA-approved impotence pill. Levitra entered the U.S. market in August 2003; Cialis became available in November 2003.

Viagra still holds a dominant market share; Pfizer said recently it has 70% of the worldwide dollar market share. But worldwide sales are starting to slide. Viagra produced $1.21 billion in sales for the first nine months of 2004, down 12% from the same period last year. The big cut in sales came in the U.S. market, where nine-month revenue fell 20% to $638 million.