Doctors Expect Oral Therapies To Dramatically Expand Erectile Dysfunction (ED) Market
NEW YORK CITY, Nov. 10 /PRNewswire/ -- "Oral therapies, certainly, will
revolutionize treatment of erectile dysfunction (ED)," says Harin Padma-
Nathan, M.D., associate clinical professor of urology at the University of
Southern California's School of Medicine in Los Angeles and director of The
Male Clinic in Santa Monica, Calif. "Eventually, nearly all ED patients will
be offered oral treatment as a first-line therapy."
Those who fail oral therapy will then progress to injection therapy, "the
gold standard," says Dr. Padma-Nathan. He told a group of science writers who
convened recently at the National Institutes of Health (NIH) in Washington,
D.C., that Senetek PLC's (Nasdaq: SNTKY) Invicorp, an autoinjectable ED drug
in development, "promises to continue the vitality of injection therapy in
this field" -- a very large market, he says.
Healthcare consultants Mehta and Isaly, in their June 1997 report, "Stiff
Competition Ahead in the Growing Erectile Dysfunction Market", conservatively
estimate that the number of men suffering from ED in the United States, Europe
and Japan could be as high as 50 million. "From less than $500 million in
1996, made up of mostly ineffective treatments, we estimate a $3.8 billion
market for erectile dysfunction in 2003," says the Mehta and Isaly report.
A number of analysts have identified at least four drugs that may be the
biggest beneficiaries of market expansion if they are eventually approved for
marketing by the FDA, including three oral drugs -- Pfizer's Viagra
(sildenafil), TAP Holdings' apomorphine, Zonagen's Vasomax (phentolamine) --
and Senetek's autoinjectable drug, Invicorp.
FDA approval of one or more oral drugs will be the key to major expansion
of the ED market, several analysts say. Other products contributing to the
growth of the market may be: Pharmacia & Upjohn's Caverject (alprostadil), an
injectable ED therapy launched in September 1995; and Schwarz Pharma's Edex,
an injectable alprostadil product that received FDA approval in June.
The term "erectile dysfunction" is a recent one, replacing the word
"impotence", though both terms refer to the same disease: an inability to
achieve erection sufficient for sexual intercourse.
Some 140 million men worldwide suffer from ED. The market can be divided
between two different causes: psychogenic and organic. Mehta and Isaly
estimate the split to be about 20 percent psychogenic, 80 percent organic.
Organic-based ED can be further broken down into: mild erectile dysfunction
(30 %), moderate (50%), and severe (20%).
According to physicians, only about 10 percent of men who have ED seek
treatment today. The problem is not that ED treatments are ineffective. More
often, the stumbling blocks appear to be ignorance that effective ED
treatments are in fact available, or embarrassment about pursuing ED
treatment, or the distastefulness associated with current therapeutic
alternatives.
"Oral drugs will be the first choice of patients once they are on the
market due to the non-invasive nature of administration," according to Mehta
and Isaly. "(However) data from various clinical trials suggest that oral
drugs do not work across the range of erectile dysfunction categories, and
some of their side effects may limit widespread use."
By 2000, industry analysts expect that at least three oral drugs --
sildenafil, apomorphine and phentolamine -- may be on the market serving most,
if not all, of the psychogenic- and some of the mild organic-based ED markets.
There is debate as to which oral drugs will lead the market when they are
approved.
While most physicians agree that the oral drugs, if approved, will evolve
into first-line therapies, David Ferguson, M.D., Ph.D., a clinical
pharmacology specialist and a consultant to the drug industry in designing
clinical trials for ED drug companies, believes that doctors will probably try
different treatments, starting with mild ED therapies and moving to stronger
ones, until their patients find one that is effective.
Injectables probably will remain the strongest pharmaceutical therapies
and likely will be the preferred option after a patient tries and fails oral
delivery methods. Two prostaglandin injectable therapies already are on the
market: Pharmacia & Upjohn's Caverject and Schwarz Pharma's Edex.
Invicorp, the autoinjectable ED therapy from Senetek, could very likely
become the leading second-line therapy, says Dr. Ferguson. In addition to its
reported 81 percent overall efficacy in clinical trials involving 718 European
men, other Invicorp advantages, he says, are its autoinjector, which makes
injections easy to perform, and the lack of a burning sensation that some men
experience with prostaglandin therapies.
Geoffrey Hackett, M.D., who founded an ED clinic near London three years
ago and has been part of clinical trials using both Viagra and Invicorp, is
currently prescribing Invicorp for about 70 percent of his ED patients (while
awaiting regulatory approval, Invicorp is available on a "named-patient" basis
in the U. K.). He believes Invicorp presents fewer problems than other ED
injection therapies because its autoinjector is easy to use and a patient
never sees, nor barely feels, the needle.
Also, says Dr. Hackett, Invicorp avoids the penile pain that he has
witnessed in approximately 30 percent of Caverject users. While he, too,
believes patients will prefer oral over injectable therapies if they work, he
notes that Viagra is less spontaneous than Invicorp because it requires at
least one hour to become effective, compared to about five minutes -- with
sexual stimulation -- for Invicorp.
"With its favorable side-effect profile, efficacy in organic erectile
dysfunction, rapid onset of erection after stimulation, ability to induce
erection up to two-and-one-half hours after administration, and natural
termination of erection after ejaculation," says Dr. Hackett, "Invicorp should
have significant market potential and certainly stands the best chance to
become the second-line therapy of choice after oral therapies."
Dr. Ferguson is even more bullish about Invicorp. "Given the substantial
data from European clinical studies, it appears to me that Invicorp ought to
be able to seize the entire injectable segment of the ED market, which I
believe will be about a 25 percent share," he says.
Ridwan Shabsigh, M.D., assistant professor of urology with Columbia
University's College of Physicians and Surgeons and director of the Sexual
Dysfunction clinic at Columbia Presbyterian Medical Center's N.Y. Male
Reproductive Center, concurs with Dr. Ferguson, adding that, "Invicorp likely
will continue the role of injectable ED therapies as the gold standard.
Invicorp's clinical data are extensive and very impressive."
At this time, Senetek's Invicorp therapy is not approved for marketing
anywhere in the world. Senetek expects regulatory approval of Invicorp in
Europe either by year-end or in the first quarter of 1998. It expects to
submit an NDA (New Drug Application) to the FDA by year's end.
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SOURCE Senetek PLC |
