In a double-blind trial of more than 300 men with a lifetime history of prematurity, researchers found that the mean time to orgasm increased from about 0.6 minutes to 3.8 minutes in those using the spray.

The findings will be presented Tuesday at a Chicago meeting of the American Urological Association, but were to be released Sunday.

This new topical spray "has promise to become one of the most effective treatments for premature ejaculation," said Dr. Ira D. Sharlip, a urologist at the University of California, San Francisco, and an association spokesman. "It has a number of characteristics which will be attractive to patients."

Premature ejaculation is one of the most common sexual problems of men, striking about one in every three -- compared with one in four for erectile dysfunction.

Researchers have generally taken two approaches to overcoming the problem, treating the brain or numbing the penis.

Scientists noted some time ago that certain anti-depressants, such as Zoloft and Prozac, had a side effect of delaying ejaculation. Johnson & Johnson developed a new drug, called dapoxetine, that maximized this effect. The drug has been approved in a couple of European countries, but the U.S. Food and Drug Administration has ruled that it is not approvable, in part because of the problems associated with long-term use of such drugs.

The other approach is to use a topical anesthetic, such as EMLA Cream, a combination of the anesthetics lidocaine and prilocaine in a cream base. It has not been approved for treating premature ejaculation, but many physicians prescribe it off-label.