Sexual dysfunction is a well-known side effect of some antidepressants, with up to 70% of men and women on antidepressants reporting sexual problems. It's a major reason depressed patients stop taking their medication, according to H. George Nurnberg, MD, the study's lead author and a professor at the University of New Mexico School of Medicine in Albuquerque. The study is published in TheJournal of the American Medical Association.
In the study, Nurnberg and his colleagues found that when women being treated with an antidepressant were given Viagra, they were more likely to have orgasms than those on the placebo.
''Seventy-two percent of the women on Viagra vs. 27% of the women on placebo got to 'much improved' or 'very much improved' on a scale [of sexual functioning],'' says Harry A. Croft, MD, medical director of the San Antonio Psychiatric Research Center in Texas and a co-author on the study.
''What Viagra did was increase the orgasm and the time to orgasm," says Croft, noting that orgasm difficulties are common in women on antidepressants. The Viagra also improved the satisfaction of the partner, he says. But ''it didn't increase drive and desire.''
The findings are no surprise to Irwin Goldstein, MD, director of sexual medicine at Alvarado Hospital in San Diego and editor-in-chief of The Journal of Sexual Medicine. "I actually prescribe a lot of Viagra for women," says Goldstein, who reviewed the study for WebMD.
Viagra for Her: Study Details
The researchers evaluated 98 women on antidepressants, average age 37 and all premenopausal, assigning half to the Viagra group and half to the placebo group for the eight-week study. Viagra doses started at 50 milligrams a day, taken one or two hours before expected sexual activity, and could be increased to 100 milligrams. No one knew which pill they were taking.
On average, the women had been taking antidepressants for two years and had suffered sexual problems for at least four weeks.
The study was conducted at seven U.S. research centers between September 2003 and January 2007.
Because sexual problems are a prime reason patients give for stopping the antidepressants, experts think it is important to find a way to relieve the sexual problems.
Before starting the study, the women reported a variety of sexual problems, including lack of libido, difficulty becoming aroused or becoming lubricated, lack of orgasm, or delay in achieving orgasm.
Viagra for Her: Study Results
Researchers used standard measures to evaluate sexual functioning and had the women keep a sexual activity log. They also assessed hormone levels.
When Nurnberg's team looked at overall sexual functioning, they found that 73% of the women on placebo had no improvement in sexual functioning but only 28% of the women taking Viagra reported no improvement.
When they looked at the individual measures, they found women treated with Viagra were significantly more likely to reach orgasm than those in the placebo group. When they looked at the individual measures, such as desire or lubrication, they did not find significant differences.
There was a significant difference, Croft says, in the partner's satisfaction.
The higher a woman's testosterone levels, the researchers also found, the more likely a positive treatment response occurred, regardless of group assignment.
The women reported some side effects, with the most common being headache, reported by 43% of the women on Viagra and 27% of those on placebo. Transient vision disturbances were reported by 14% of those on Viagra and 2% of those on placebo. No one dropped out of the study because of their side effects. In those women who continued their dose of antidepressants, their depression didn't worsen during the study, regardless of their group assignment.
The study was supported by an independent grant from Pfizer, which makes Viagra. The grant was initiated by the researchers and the pharmaceutical company had no other role in the study, the researchers say.
The study, Croft says, ''is the first and only double-blind, randomized trial that shows it works for this.'' Viagra, he notes, is not approved by the FDA for use in women, so the use is ''off-label'' and not typically covered by insurance.
Viagra for Her: Second Opinion
Evaluating a woman's hormone levels before prescribing Viagra for sexual problems is important, says Goldstein, who is also a clinical professor of surgery at the University of California, San Diego. Normal testosterone levels, he says, are crucial for the successful effect of the drug.
"What Viagra does in women with normal testosterone [levels] is engorge their clitoris [with blood], which allows them to have orgasm," he tells WebMD. "Viagra acts on a man's penis and a woman's clitoris."
The finding that the drug did not affect desire or arousal comes as no surprise, either, he says. "Viagra has never been shown to increase desire in men or in women."