FRIDAY, Sept. 8 (HealthDay News) -- A new antidepressant drug designed specifically to treat premature ejaculation proved safe and effective in two large trials, researchers report.

However, it's not likely that dapoxetine, a short-acting selective serotonin reuptake inhibitor (SSRI), will win U.S. approval anytime soon because it can produce side effects, one expert said.

SSRIs, which are used to treat depression and other psychiatric disorders, are now also used "off-label" as a treatment for premature ejaculation. They work because one of their side effects is to delay ejaculation. But, continued SSRI use can have some negative side effects, such as psychiatric problems, skin reactions, weight gain, and loss of libido, experts said.

"This is the first drug specifically developed for premature ejaculation," said lead researcher Dr. Jon L. Pryor, a professor and chairman of urologic surgery at the University of Minnesota. "It worked both in lengthening ejaculation time and in patients' feeling control over ejaculation and both subjects' and partners' feelings of satisfaction with intercourse," he said.

The findings are published in the Sept. 9 issue of The Lancet.

Premature ejaculation is the most common male sexual problem, even more common than erectile dysfunction, affecting 21 percent to 33 percent of American men.

In the study, Pryor and his colleagues looked at the combined results of two trials that tested dapoxetine. The trials included 2,614 men who had moderate to severe premature ejaculation.

The men were randomly assigned to receive a placebo or different doses of dapoxetine. They were told to take the drug one to three hours before having sex. At the start of the study, the men ejaculated, on average, in less than a minute after penetration.

However, after 12 weeks, men taking dapoxetine increased their time to ejaculation to 2.78 minutes for those receiving a 30-milligram dose, and to 3.32 minutes for those receiving a 60-milligram dose, the researchers found. For men taking a placebo, the time to ejaculation averaged 1.75 minutes.

Pryor thinks this study will get people talking more about the problem of premature ejaculation. "I hope this paper brings premature ejaculation out of the closet," he said. "I hope it allows for mature discussion about it, and that people realize that there is hope."

One expert familiar with dapoxetine thinks the drug has promise but will not be available in the United States.

"The problem is that dapoxetine was presented to the U.S. Food and Drug Administration last year, and they rejected it out-of-hand as a treatment for premature ejaculation," said Dr. James Barada, director of the Center for Sexual Health in Albany, N.Y.

The drug can produce side effects such as nausea, headache, upset stomach and weakness. It is being released in Europe, Barada said.

"Premature ejaculation is a real clinical condition that causes distress for the man, his partner and especially the relationship," he added. "Because we have no approved therapy, we are at somewhat of a loss to treat it. For many years, we have been using off-label therapies -- SSRIs -- because of the side effect they have of delaying ejaculation."

Doctors can still use SSRIs, Viagra, and psychotherapy to treat the problem, Barada said. "We need to get better research to understand the mechanisms of premature ejaculation and hopefully design a medicine that has good efficacy and safety that is not an SSRI," he said.

More information

The U.S. National Library of Medicine can tell you more about premature ejaculation.