Pfizer puts halt to tests of Viagra for women without clear res

NEW YORK -- Pfizer Inc. is ending research on whether the anti-impotency drug Viagra can be used treat female sexual problems because studies on women were inconclusive, the company said.

The results of several clinical studies involving about 3,000 women did not support a regulatory filing, Pfizer said Friday.

Karen Katen, executive vice president of Pfizer and president of Pfizer Global Pharmaceuticals, said that while the company was disappointed that the program was not more successful, "this is the nature of drug development."

Experts agree that female sexuality is more complex than male sexuality, involving psychological and physical factors.

Joe Feczko, president of Worldwide Developing at Pfizer, said diagnosing sexual difficulties in women "involves assessing physical, emotional and relationship factors, and these complex and interdependent factors make measuring a medicine's effect very difficult."

At least 10 pharmaceutical companies have sought to develop a female equivalent for Viagra since the drug was launched in 1998 as a treatment for male sexual disfunction.

More than 23 million men have been prescribed Viagra since then, Pfizer said.

Pfizer said it began researching into whether Viagra would work for women in 1996 and is studying other treatment approaches.