The Search for Female Viagra

The pharmaceutical industry's push to find a female version of Viagra has been full of letdowns.

Despite a decade of testing pills, patches, gels, nasal sprays, and vaginal rings, there is still no approved drug for "female sexual dysfunction." More than a dozen drugs that reached late-stage testing have been abandoned, shelved, or recycled for unrelated problems.

Market analysts still see multibillion-dollar opportunity in female sexual complaints. And two drugs -- LibiGel and Flibanserin -- doggedly aspire to become the first to win the FDA's imprimatur.

But female sex disorders have turned out to be far more difficult to define and quantify, let alone fix, than erectile dysfunction.

Kathy Kelley, the Texas founder of HysterSisters, a Web site for women who have had hysterectomies, testified before the U.S. Food and Drug Administration about the clear-cut need for drug therapies.

But she also understands how complex and individual those needs are.

"The brain is a woman's primary sex organ," she said in an interview.

Different from men With the 1998 approval of the first male impotence drug, entrepreneurs, researchers, and many members of the fairer sex began lusting after a "pink" version.

Indeed, the first drugs to be tested in women were blood-vessel dilating agents that included Viagra and Cialis. The hope was that women would follow the classic male model of sexual response -- interest, arousal, orgasm.

They did not. Pfizer Inc.'s research showed that genital blood flow increased in Viagra-treated women as they watched erotic videos, but the arousal did not make them desire sex.

The complexity of female response has kindled intense debate. How to distinguish normal from abnormal, physiological from psychological, discontent from debilitation?

The answers have financial implications, especially as most drugs for women have been designed to be used regularly and indefinitely, not just as needed to prime the pump.

"In order to get insurance coverage, you have to prove this is a defined medical disorder that is really disrupting your life," said Leslie Sandberg, a market analyst at Trinity Partners in Waltham, Mass. "The vast majority of Viagra sales are cash pay; infrequently is it covered."

In 2000, the FDA issued preliminary guidelines to help companies plan human studies of drugs for female sexual complaints. The guidelines -- still not finalized -- reflected the consensus that had emerged among sex experts at industry-supported conferences around that time.

The FDA said that although "the definition of FSD continues to evolve," it "currently" has four "components:" decreased desire, decreased arousal, sexual pain, and orgasm difficulties.