A new drug keeps the stopwatch ticking longer for men with premature ejaculation.

The finding comes from a study of more than 2,600 monogamous men testing a new drug, dapoxetine, under development by Johnson & Johnson subsidiary Ortho-McNeil, a WebMD sponsor. One to three hours before sexual intercourse, the men took one of two doses of dapoxetine or a placebo pill.

With their partners, the men used a stopwatch to measure their "intravaginal ejaculatory latency time." This measures the time that elapses between vaginal penetration and ejaculation; fewer than two minutes is considered abnormal or capable of causing distress.

Before treatment, they averaged 54 to 55 seconds. There's some support for the "it's all in the mind" crowd because just taking an inactive placebo pill upped the men's time to 1.75 minutes. But the "it's all in the brain" theory got much better support. Men taking dapoxetine increased their time to 2.78 minutes for low-dose dapoxetine (30 milligrams) and to 3.32 minutes for the higher dose (60 milligrams).

That's a meaningful improvement, says study leader Jon L. Pryor, MD, chairman of urologic surgery at the University of Minnesota.

"The results with dapoxetine are compelling," Pryor says in an Ortho-McNeil news release. "They demonstrate that, for the first time, a medicine can be taken by men on an on-demand basis and provide significant improvement in their premature ejaculation condition."

Pryor reported the findings at the annual meeting of the American Urological Association in San Antonio. The study was funded by Ortho-McNeil.

Serotonin for Premature Ejaculation

Dapoxetine is a member of a class of drugs called selective serotonin reuptake inhibitors or SSRIs. This class of drugs includes several antidepressant medications such as Paxil or Zoloft that have also been used for the treatment of premature ejaculation. They work by increasing the amount of a chemical, serotonin, in the brain.

Studies suggest that men with premature ejaculation have too-low serotonin levels. Dapoxetine has a potent, quick-acting effect on serotonin levels that makes it possible to explore its use as a premature ejaculation treatment.

Better Sex for Men With Premature Ejaculation

Pryor didn't just measure how long it took men to ejaculate. He also asked the men to rate how well they thought they were able to control ejaculation.

Before treatment, only about 3 percent of the men reported at least fair control over ejaculation. After placebo treatment, a surprising 26.4 percent of men reported fair control. Even so, more men reported fair-or-better control after taking dapoxetine: 51.8 percent in the low-dose group, and 58.4 percent in the high-dose group.

Pryor's team also asked the men and their partners about their sexual satisfaction. Interestingly, the men and their partners were in fairly close agreement.

Before treatment, only about 20 to 25 percent of the men and their partners reported "good to very good" sexual satisfaction. This increased to about 25 percent of men and partners in the placebo group but to about 39 percent in the low-dose group and about 47 percent in the high-dose group.

Dapoxetine Side Effects

Dapoxetine treatment was not without side effects, however. These included:

--Nausea in 8.7 percent of men getting low-dose and 20.1 percent of men getting high-dose dapoxetine.

--Headache in 5.9 percent of men getting low-dose and 6.8 percent of men getting high-dose dapoxetine.

--Diarrhea in 6.8 percent of men getting high-dose dapoxetine.

--Dizziness in 6.2 percent of men getting high-dose dapoxetine.

Side effects made 10 percent of the men in the high-dose dapoxetine group and 4 percent of men in the low-dose group stop treatment. Less than 1 percent of men in the placebo group stopped treatment due to side effects.

Despite these side effects, Pryor and colleagues report that "both doses of dapoxetine were well tolerated."

Levitra May Help, Too

In another study presented at the AUA meeting, the erectile dysfunction drug Levitra appeared to help premature ejaculation.

Frank Sommer, MD, PhD, a urology specialist at the University Medical Centre in Cologne, Germany, reported a small study in which 37 men with premature ejaculation received either Levitra or the SSRI antidepressant Zoloft.

Both drugs improved premature ejaculation severity, although much stronger effects were seen for Levitra than for Zoloft. And Levitra also improved partner sexual satisfaction.

"There is a potential usefulness of [Levitra] as a promising line of therapy in premature ejaculation," Sommer and colleagues wrote in their presentation abstract.

By Daniel J. DeNoon, reviewed by Brunilda Nazario, MD

SOURCES: American Urological Association's 2005 Annual Meeting, San Antonio, May 21-26, 2005. News release, Ortho-McNeil.