TUESDAY, July 22, 2008 — Viagra is used by millions of aging men for erectile dysfunction, but most research suggests it doesn’t do much for women’s sex lives.

However, a new study suggests that the “little blue pill” could benefit some women. The small, Pfizer-funded trial found that it improved orgasm in premenopausal women who had sexual difficulties due to antidepressant use.

About 1 in 10 women in the U.S. take an antidepressant drug, according to a 2004 survey. And those drugs, particularly selective serotonin-reuptake inhibitors (SSRIs) such as fluoxetine (Prozac) and sertraline (Zoloft), are known to be sex-drive killers for men and women.

Study suggests drug works in select women
In the study, H. George Nurnberg, MD, of the University of New Mexico School of Medicine in Albuquerque, and colleagues randomly assigned 98 women, with an average age of 36, to take sildenafil (Viagra) or a placebo.

All of the women were taking antidepressants (mostly fluoxetine or sertraline), and they took a Viagra or a placebo pill about one to two hours before they had sex during an eight-week period, according to the report in Journal of the American Medical Association. (Both researchers and the women were blinded as to who received the placebo and who did not.)

Almost three-quarters of the women who received the placebo reported no improvement in their sex lives compared with only 28% of those who took Viagra. On average, the Viagra users were more likely to reach orgasm (and were more satisfied with them) than placebo-takers.

That sounds promising. However, you have to keep in mind that it’s a manufacturer-funded study, a type of trial that is generally not considered as reliable as research that is conducted independently. And, as the report discloses, Dr. Nurnberg and other co-authors have received research funds and acted as paid consultants to Pfizer and other drug companies in the past.

Needs to be confirmed in larger group of women
About 22% of the women dropped out of the trial, so only 39 Viagra users completed the study, notes Marjorie Green, MD, director of the Mount Auburn Menopause and Female Sexual Medicine Center in Cambridge, Mass., and a clinical instructor at Harvard Medical School.

“All of the other studies on sildenafil [in women] have not been positive,” says Dr. Green. And the patient group is so small in this study, “I think it would be hard to use the results without further study.”

In addition, Viagra is not FDA-approved for use in women, so the risks to women are not completely clear. (Pfizer dropped its effort to get FDA-approval for women after disappointing trials in pre- and postmenopausal women with sexual arousal disorder, according to the study.)

In the recent research, Viagra users suffered from more headaches, nasal congestion, flushing, and visual problems than those who took the placebo.

Viagra and similar drugs inhibit an enzyme (phosphodiesterase type 5) found in eye tissue, male genitals, and other parts of the body. Blocking the enzyme causes smooth muscle to relax and increases arterial blood flow to the penis. This is beneficial to men with erectile dysfunction because it allows more blood to fill the vessels and increases their ability to sustain an erection.

Female sexual dysfunction is more complicated, but similar enzyme signaling is thought to take place in female genital tissue. So it’s possible that phosphodiesterase type 5 inhibitors may help some women.

Select group of women may benefit
Andrew T. Goldstein, MD, cautions that the findings should not be extrapolated to patients outside the range of the trial. However, he said that sexual medicine experts do think Viagra is worth trying in some female patients.

“This would not be a drug to be used for a 55-year-old woman who complains of decreased desire who is not on SSRIs,” says Dr. Goldstein, an obstetrician and gynecologist at Johns Hopkins School of Medicine and an associate professor at George Washington University, who specializes in treating women’s sexual dysfunction. “If it’s used for that, you’re not going to get results, and you’re going to have a frustrated patient.”

However, for patients who are having sexual side effects of antidepressants, Dr. Goldstein says, “It’s worth trying.”

According to Dr. Green, many women start taking antidepressants without even being told that they can cause sexual side effects.

An ongoing Internet survey being conducted by the Women’s Sexual Health Foundation (Dr. Green is on the advisory board) suggests that more than half (54%) of women taking antidepressants were never informed of the potential side effect. In all, 75% of those surveyed said they’ve had a decrease in sexual desire since starting the drugs.

Antidepressant-induced sexual dysfunction is “a big problem,” says Dr. Goldstein. “Premenopausal women 18 to 50 often will discontinue their antidepressants because of sexual side effects. So they are focusing on a very important group of women with a very important problem.”

(PHOTO: GETTY IMAGES/ISTOCKPHOTO/HEALTH)

By Theresa Tamkins

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