from issue of
April 6, 1998 |
Cross-Gender Sex Pill
A new drug designed to treat impotence in men may have
surprisingly similar effects in women
By ARNOLD MANN
Irwin Goldstein could hardly wait for the FDA to approve Viagra.
The renowned Boston University urologist is so excited about
last week's approval of the first-ever impotence pill for men
that he is opening a new sexual-dysfunction clinic, and will
soon begin prescribing the drug--for women.
As doctors learn more about the causes of impotence, they're
becoming increasingly convinced that the underlying mechanisms
of male and female sexual dysfunction may not be so far apart.
And if that's the case, it's entirely possible that the same
pharmacological science that restores sexual function to men can
work similar magic in women.
Viagra trials in women are already under way in Europe. In April
the FDA is holding an invitation-only meeting of scientists and
pharmaceutical executives to discuss possible testing and use of
the drug in women in the U.S. And in June leading sex
researchers will devote their annual meeting in Cape Cod to
discussing how a range of impotence drugs might be tested in
female patients. If the medications prove effective, they could
offer women a safer alternative to the current best weapon
against female sexual dysfunction, hormone-replacement therapy,
which carries a slightly increased risk of cancer. Meanwhile,
with the approval of Viagra (release date: mid-April) as an
impotence treatment, doctors will be able to prescribe it
"off-label" for women too. "We intend to use it in women once
it's released for men," Goldstein says. "Not even a question."
Viagra's effects on the hydraulics of male sexuality are pretty
straightforward. Originally developed as a heart medication, the
drug works directly on the blood vessels, blocking an enzyme
called phosphodiesterase. This enzyme prevents the release of
certain neurotransmitters--most notably one called cyclic
GMP--that cause the smooth muscles surrounding arteries to
relax, allowing the arteries to expand. When this occurs in
penile arteries, it leads to engorgement, which leads to
erection.
While Viagra doesn't work for every impotent man, it does work
for up to 80% of them. "There appears to be no group that has
been tested that has a zero response," says urologist Dr. Harin
Padma-Nathan of the University of Southern California. Even men
with the most severe forms of impotence--spinal-injury victims,
diabetics, those who have undergone prostate-cancer
surgery--have responded.
Such results ought to mean good things for women too. Female
genitals fill with blood during sexual stimulation just as male
genitals do, resulting in engorgement of the clitoris and
lubrication of the vagina. As women age, they experience some of
the same genital problems men do, as a number of
ailments--particularly atherosclerosis and diabetes--impair
blood flow; this leads to vaginal dryness, pain during
intercourse and problems in achieving orgasm. Indeed, according
to one study, more than a third of women in the 18-to-59 age
group experience sexual dysfunction, compared with just 10% of
men. "Male sexuality has always been viewed as more important,"
says Julia Heiman, a psychologist at the University of
Washington and one of the nation's leading experts on female
sexual dysfunction. "A man needs an erection to have
intercourse, so it's easy to regard a man's sexuality as
important and a woman's as sort of an interesting pastime."
How effective Viagra is in women awaits the outcome of the
tests. The FDA and Pfizer, the manufacturer, do not encourage
women to use it. "We strongly recommend against women taking
their husband's pills or physicians using it off-label," says
Raymond Rosen, professor of psychiatry at the Robert Wood
Johnson Medical School in New Jersey, who will chair the Cape
Cod meeting.
Still, when it comes to Viagra, some physicians see potential
benefits in careful, off-label use. Goldstein plans to test
female patients--mostly postmenopausal women--for impaired blood
flow and give the drug to those he thinks it can help. He has
already received E-mail from women eager to try it. Other
doctors are bracing for the same. "The Viagra avalanche is about
to begin," says Rosen. "Where the oral contraceptive was
liberating for younger people, Viagra may be the
sexual-liberation pill of older adults." This time both men and
women will be getting in line.
Impotence Drugs in the Works for Women
--Viagra (chemical name: sildenafil): Relaxes muscle cells to
enhance blood flow. Early female trials under way in Europe;
U.S. female trials will be discussed at an FDA meeting later
this month
--Vasomax (phentolamine): Oral version of an approved injectable
drug. Dilates blood vessels to increase flow. Male trials are
near completion in the U.S.; female trials are planned
--Spontane (apomorphine): Works through the central nervous
system. Male trials are nearing completion; female trials are
planned
--Prostaglandin creams: Applied to surface of the genitals to
stimulate blood flow. Male trials under way; female trials planned
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