A 24-Hour Viagra?

N E W   Y O R K, May 1 -- Viagra is a hard act to follow, but a new drug under development hopes to give the little blue pill some stiff competition.

Cialis, a drug being developed by Eli Lilly and Co. and Icos Corp., may be able to give men erections for 24 hours after they take the drug, or approximately 20 hours longer than Viagra can.

"Cialis has the potential to be a valuable new treatment option for men with ED [erectile dysfunction] and their partners," says Dr. Harin Padma-Nathan, a urologist with the University of Southern California and lead investigator of two studies testing the drug for the companies.

"A therapy that allows a man with ED to engage in intercourse within a 24-hour window permits the couple to regain spontaneity in their sexual relationship."

Viagra's manufacturer, Pfizer, Inc., recommends men take Viagra about one hour before engaging in sexual activity. The drug helps men get an erection if they are sexually excited in about 30 minutes, and it lasts up to four hours, the company says.

Erections Up to 24 Hours Later

In one of the studies being reported today, 61 men with mild to severe erectile dysfunction received either Cialis or a placebo in a clinical setting. The doctors were not aware which patients received the drug or the placebo until after the data was collected.

After taking the drug and looking at sexual images, the doctors measured the men's response with a RigiScan, or a device that measures the firmness and duration of erections.

The men taking the Cialis were more successful at achieving erections, even up to 24 hours later, Padma-Nathan reports.

Sixteen Minutes to Action?

In another study, 223 men took the drug or a placebo at home, in a more natural setting. The men were instructed to take the drug before engaging in sexual activity and to use a stopwatch to record the time it took to achieve an erection.

Men were able to get an erection as early as 16 minutes after taking the drug and could have a second sexual encounter up to 24 hours later, Padma-Nathan found.