Erectile Dysfunction
New Drugs May Soon Challenge Viagra's Dominance
By Bill Berkrot
Apr 18, 2002, 5:24am

NEW YORK (Reuters) - Viagra may be in for its first real competition as two new anti-impotence drugs take on Pfizer's famous little blue pill.


The challenge to Viagra's domination of the erectile dysfunction (ED) market is expected to come this year from the drugs Cialis and vardenafil. Cialis is a joint venture of Eli Lilly & Co and Icos Corp., and Bayer AG's vardenafil will be co-marketed with GlaxoSmithKline Plc . "On paper, the two new drugs look better than the current one," Dr. Wayne Hellstrom, a professor of urology at Tulane University said, noting that the new drugs appear to work in smaller doses than Viagra and with fewer or milder side effects.

Doctors whose patients have participated in trials of the new drugs say all three are safe and effective, but point out that direct comparisons cannot be made without head-to-head testing of Viagra versus the newcomers.

"Once these drugs come out and compete I think they'll all do quite well," Hellstrom said.

US Food and Drug Administration approval for both drugs is likely in the second half of 2002, the drug makers said. European approval could also come later this year.

While claims of superiority over Viagra cannot be made by the upstarts without comparison tests, clinical trials appear to have demonstrated that Cialis and vardenafil begin to work faster than Viagra and that the effects of Cialis last far longer.

Viagra takes about an hour to work and it is recommended that sexual relations take place within four hours.

Cialis has demonstrated it can begin to work in as little as 16 minutes and remains effective for at least 24 hours. Eli Lilly plans to present data at next month's American Urological Association meeting in Orlando, Florida, showing that Cialis has allowed normal sexual function in some men for up to 36 hours.

"It means an opportunity to provide patients with a wide window of effectiveness and permit them to have flexibility in timing of sexual activity and spontaneity in sexual activity," said Columbia University Associate Professor Dr. Ridwan Shabsigh, director of the New York Center for Human Sexuality.

The need to plan sexual activity within a limited time has been one of Viagra's drawbacks. Yet Viagra racked up more than $1.5 billion in sales worldwide last year.

Some 500,000 physicians have written Viagra prescriptions for 15 million patients globally, and seven tablets of Viagra are prescribed every second worldwide, Pfizer Inc. said. And that's just the tip of the iceberg.

"The great majority of patients with ED have not sought treatment," Shabsigh said.

Hellstrom estimated that more than 80% of some 40 million men suffering some degree of erectile dysfunction have yet to seek treatment for the disorder.

So the folks at Pfizer are not exactly quaking in their boots at the prospect of competition.

In fact, doctors and industry analysts believe that both new drugs could garner a hefty piece of a burgeoning market while Viagra sales would continue to grow.

"There's still lots of potential that's been untapped because some men are still shy and embarrassed," Janice Lipsky, head of Pfizer's US Viagra team, said. "It's not as though it's a mature market at all."

It remains to be seen whether Lilly or Bayer will be able to match the marketing muscle of industry giant Pfizer, which even got conservative former US senator and presidential candidate Bob Dole to sing Viagra's praises.

"I think it will be a challenge for them to go up against the recognition that Viagra has," Lipsky said. Urologists are hoping the upcoming marketing push will help destigmatize erectile dysfunction and greatly increase the number of men seeking treatment.

We will see efforts by major pharmaceutical companies "to educate patients about the condition that causes frustration, embarrassment ... changes in partner relations, depression, (letting them know) that there are treatments available to them," said Dr. Irwin Goldstein, director of the Center for Sexual Medicine at Boston University School of Medicine.

The new drugs work much like Viagra. All block an enzyme called phosphodiesterase-5, or PDE-5, relaxing smooth muscle cells to allow increased blood flow to the penis.

"Of the three, by far the most selective drug is vardenafil with no reaction to other PDEs," Goldstein said.

That selectivity reduces side effects such as Viagra's notorious blue vision, which Goldstein explained occurs because Viagra also affects an enzyme in the retina.

Physicians were also enthusiastic about the new drugs' effectiveness in men with diabetes, considered among the most difficult patients to treat.

None other than Playboy founder Hugh Hefner once declared Viagra the greatest recreational drug ever invented. Soon the candy dishes at the Playboy mansion may offer alternatives.

"It is one of the most magical medications on Earth," Goldstein said of the PDE-5 inhibitors. "It's a miracle."

© Copyright 2002, All Rights Reserved -Center For Clinical Age Management, Inc.