Move Over, Viagra

Two erectile dysfunction medications, touted to last longer, await FDA nod

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By
HealthDay Reporter

THURSDAY, Feb. 27, 2003 (HealthDayNews) -- Two new medications for erectile dysfunction are poised to battle Viagra for a piece of the lucrative male health dollar.

Cialis (tadalafil), by Eli Lilly, recently won approval for European distribution and is already available online to men worldwide. Levitra (vardenafil), by Bayer, should soon follow suit. Both are awaiting approval from the U.S. Food and Drug Administration for sale in the United States and are expected to arrive at a drugstore in your town before the end of 2003. And both last longer than Pfizer's Viagra (sildenafil citrate).

Before you get your hopes up, doctors warn that newer is not always better -- and if a man fails on Viagra, chances are he may not do well on either of the new medications.

"All three drugs work pretty much the same way, so if Viagra didn't help you then you might have the type of problem that does not respond to this kind of treatment," says Dr. Andrew McCullough, director of the sexual health and male infertility and microsurgery programs at New York University Medical Center. He conducted clinical trials on all three drugs.

All three work by inhibiting an enzyme known as phosphodiesterase 5 (PDE-5). As a result, following sexual stimulation, the smooth muscles of the penis are able to relax and widen, allowing more blood flow to enter and an erection to occur.

Although the formulas may work in a similar fashion, the big difference is how long they remain active in the bloodstream -- and for some men that could prove an important detail.

"Both Levitra and Cialis have what is known as a longer 'half life' -- which means they remain active in the body longer and allow for a longer period of time in which a man can have an erection," says Dr. Natan Bar-Chama, the director of male reproductive health at the Mount Sinai School of Medicine in New York City.

According to the drug's manufacturers, Cialis remains active for a full 24 hours, with 59 percent of men reporting effects for up to 36 hours. Levitra has a similar time profile. The effects of Viagra, introduced in the United States in 1998, lasts three to four hours -- although some men have reported benefits lasting up to 12 hours. The absorption of Viagra is also inhibited by food, which is not the case for the other two drugs.

Bar-Chama says the larger window of opportunity that Cialis and Levitra allow for spontaneous sex, along with slight differences in the individual formulations, may give some men who could not perform well on Viagra a new chance to succeed.

"I tell my patients it's certainly worth a try. But I also caution them not to get their hopes up if they failed to respond to Viagra at all. If so, the newer drugs are not likely to offer any greater chance for success," Bar-Chama says.

To date, there have been no studies comparing any of these drugs to each other.

In the past, however, Viagra came under fire when isolated reports linked it to adverse cardiac events in men. Ultimately, the connection was never proven -- and the latest studies show it may actually have beneficial effects on blood flow. That said, Viagra is still not recommended for men using medications containing nitrate -- drugs normally prescribed to treat chest pains and angina.

Because both Cialis and Levitra work in much the same way as Viagra, they are likely to carry the same precautions when they are approved for sale in the United States. All three drugs also share similar common side effects, including headaches, (14 percent) and heartburn, (9 percent).

Studies show 150 million men worldwide suffer from erectile dysfunction, with no more than 10 percent seeking treatment.

More information

To learn more about erectile dysfunction, visit The Urology Channel.Or check out The National Institutes of Health.

SOURCES: Andrew McCullough, M.D., professor, urology, and director, sexual health and male infertility and microsurgery programs, New York University Medical Center, New York City; Natan Bar-Chama, M.D., assistant professor, and director, male reproductive health, Mount Sinai Medical Center, New York City

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