Key to Female Viagra Seems a Brain Teaser

Elizabeth Belt remembers holding the two pale-blue, diamond-shaped pills in the palm of her hand before swallowing them and thinking: “Please God, let this work.”

The 35-year-old Richmond, Ind., woman has been desperately unhappy for years over the sexual problems she has suffered since undergoing routine gynecological surgery when she was 19.

Belt now pins her hopes on Viagra, the hot-selling impotence pill for men. Although the first published study of Viagra in women proved less dramatic than anticipated, the sizzling market it created among men has sent researchers and drug companies racing to find its female equivalent.

“The world is finally coming around for women,” said Dr. Jennifer Berman, a urologist who runs the Women’s Sexual Health Clinic at Boston University with her sister, Laura Berman, a psychotherapist.

But the search for a female Viagra has led researchers to an important conclusion: The key to improving sexual function in women may lie in stimulating the libido. For women, scientists are finding, the most important organ for sexual function may be the brain.

“Viagra is really, literally, a functionally acting drug--it does something mechanically,” said Roland Gerritsen van der Hoop, vice president of clinical operations for Solvay Pharmaceuticals in Atlanta, one of the companies testing a libido-enhancing drug for women. “It won’t work if desire isn’t there.”

Dr. Steven A. Kaplan, a urologist at New York Presbyterian Hospital who conducted the first published study of Viagra in women, agreed that enhancing desire could be more important for women than increasing blood flow to the primary sex organs.

“Many women define sexual pleasure as arousal without orgasm and some disassociate desire and arousal from the act of intercourse,” Kaplan said.

The winning drug could produce an enormous windfall. Viagra, which Pfizer Pharmaceuticals put on the market last spring, enjoyed $788 million in sales last year. The market for women may be even more promising. A recently released study found that four of every 10 American women are having problems in the bedroom.

One libido-enhancing drug currently being tested in clinical trials among women is a chemical called apomorphine, which stimulates the brain.

It is a pill that will be sold under the name Uprima and it has already been studied--and judged effective--for increasing men’s sexual desire. The company plans to seek Food and Drug Administration approval for men later this year. It could take several additional years before it is approved for women.

Another drug that could win the race for a female Viagra has been on the market for 35 years.

The hormonal combination known as Estratest, made by Solvay Pharmaceuticals, is a mixture of estrogen and male androgens used to treat symptoms of menopause. Women taking it have reported a most pleasurable side effect: an increase in sexual desire.

Kaplan’s Viagra study, which was conducted on 30 post-menopausal women, showed that only about a quarter of the women experienced significant changes. The results were disappointing to some, but Kaplan noted that larger studies on other groups of women are needed before any conclusions about Viagra in women can be made. In the meantime, he said, improvement was “certainly significant in those women.”

Pfizer has launched a study of the drug in several hundred European women.

And some clinics are giving Viagra to women already. The Bermans have been treating sexually dysfunctional women in their Boston clinic with a combination of approaches, including Viagra. They have found that Viagra seems to work best in certain women and not at all in others.

“The women who benefit most are women who were able to become aroused before,” Laura Berman said. “If they have never been able to become aroused or have an orgasm, Viagra is not extremely useful. It’s not a libido pill. It’s not something that enhances desire.”

For Elizabeth Belt, who is engaged to be married, the trouble started 16 years ago after a routine dilation and curettage, a procedure involving scraping the walls of the uterus, after a miscarriage.

But the surgery apparently caused nerve damage within her vagina, causing her to lose all sensation there. In recent years, she began to experience a similar numbness in other genital areas. She was evaluated at the Bermans’ Boston clinic in February. After taking Viagra, she said, sensation has started to return.

“I’m hopeful now,” she said. “Before, I didn’t have any hope at all. I just thought, ‘I’m going to be like this forever.’ ”