Viagra may help female patients, researchers find

The long search for the female equivalent of Viagra has led researchers to ... Viagra.

In a study of 98 women being published today, the little blue pill helped women whose sexual performance had flagged as a side effect of taking antidepressants, a specific finding that could open a new use for the impotence drug for men.

The report in the Journal of the American Medical Association is one of the few to find some benefit for women despite nearly a decade of searching by its maker, Pfizer. More than 6 million women in the United States have major depression. Antidepressants are the most common treatment for the mood disorder, and though they can be a blessing, they often bring on debilitating sexual side effects.

Doctors said the study, which was funded with a grant from Pfizer, could foster broader experimentation with Viagra for women. Its effectiveness in women is limited compared with men, and Pfizer has said it has no intention of developing the drug for female disorders.

Not long after Viagra was introduced in 1998 to treat erectile dysfunction in men, Pfizer started researching its use in women. The company hoped to add to the success of Viagra, which had worldwide sales of $1.76 billion last year.

Initial studies of Viagra in women were disappointing. The drug blocks an enzyme that inhibits blood flow, which, in the case of men, allows more blood to flow to the penis. In women, the drug increased engorgement of genital tissue but failed to enhance women's enjoyment of sex. Pfizer ended company-initiated trials of the drug for sexual-arousal disorder in women in 2004.

However, many doctors said the early studies weren't selective enough because they included women who lacked desire. Such women, like men with desire problems, couldn't expect to be helped by Viagra.

The latest study was confined to women with arousal problems. The women had been diagnosed with major depressive disorder and were taking a specific class of antidepressants called selective serotonin reuptake inhibitors, or SSRIs. Their depression was in remission when the study began.

The women, all of whom were pre-menopausal, were divided into two groups. Half were assigned to take Viagra one to two hours before sexual activity for eight weeks. The remaining women received the same instructions but were given a placebo.

At the end of the study, 72 percent of women taking Viagra, and 27 percent of those taking a placebo, reported improvement. The side effects were those typically associated with Viagra, including headaches and flushing. The women who responded best tended to have higher levels of testosterone, a phenomenon also observed in men taking Viagra.

Julia Heiman, director of the Kinsey Institute for Research in Sex, Gender and Reproduction at Indiana University and a study author, said the findings were important because the sexual side effects of antidepressants can be so debilitating that women discontinue their medications, putting themselves at risk for greater depression.

"This will change practice," said Dr. Andrew Leuchter, a professor of psychiatry at the University of California, Los Angeles, who was not connected to the research.