Longer-Lasting Erection Drug Approved

Nov. 21, 2003 -- Look out, America, here comes "Le Weekend." That's what the French are calling the newest erectile dysfunction drug approved by the FDA.

It's called Cialis -- pronounced "SEE-Alice." Like Viagra and Levitra, it doesn't make a man's penis erect. Instead, the drugs make it possible for a man who's had trouble getting and keeping erections to have one when he's sexually aroused.

Viagra starts working in about half an hour, and its effect lasts for about four hours. Levitra has about the same window of effect. Cialis gets to work a bit faster -- a third of men respond in 15 minutes -- but lasts for 36 to 48 hours in some men (but by no means all).

Urologist Gerald Brock, MD, associate professor at St. Joseph's Health Center in London, Ontario, is past chairman of the Canadian Male Sexual Health Council. He's treated many patients with Viagra and, in clinical trials, with Cialis and Levitra.

"Cialis will be an important addition to the way we treat men with erectile dysfunction," Brock tells WebMD. "It provides an opportunity for many men to take a pill and have a window of opportunity that extends 36-48 hours where they will have a significant improvement in their sexual function."

Cialis is manufactured by Eli Lilly and Co. and ICOS Corp. Lilly is a WebMD sponsor.

There's another important difference between the three drugs. Viagra takes longer to work if taken after a high-fat meal. Cialis and Levitra can be taken on a full stomach regardless of what you've eaten.

Chad Ritenour, MD, teaches urology at Atlanta's Emory University. He says lots of patients will want to try the new drug.

"I tell patients it is going to be like Pepsi vs. Coke -- get ready for the advertising blitz," Ritenour tells WebMD. "But I don't think anybody can say one works better than the other. Each drug probably will work better for some patients than for others."

How They Work

All three drugs work the same way. They block an enzyme called PDE-5, a natural chemical that's part of the chain of chemical messages that tell a man's erection to go away. Brock says that there's more PDE-5 in the penis than in other areas of the body, so the drugs have a pretty specific effect.

However, Viagra and Levitra sometimes block a sister chemical -- PDE-6 -- that affects color vision. Some men report a slight bluish tinge to their vision; some become more sensitive to light. These effects go away in a few hours. Cialis doesn't seem to have this effect.

Cialis has a different side effect. It blocks PDE-11, which is found in many parts of the body including the smooth muscles of the internal organs, the heart, skeletal muscles, the pituitary gland, and in the germ cells of the testes. So far, Cialis seems to have no harmful effect on these tissues. But PDE-11 may be involved in Cialis' most troublesome side effect: Back pain. According to a spokesperson for Lilly ICOS, back pain was reported by 5% of patients taking 10 mg of Cialis and 6% at the 20 mg dose. Patients taking placebo reported back pain 3% of the time.

Which one do men like best? In a recent head-to-head-to-head study of all three drugs taken at the recommended starting dose by men with erectile dysfunction:

• 47% preferred Levitra.
• 34% preferred Viagra.
• 19% preferred Cialis.