Los Angeles Times (US), December 6, 2004
Closer to a male
studies and changes in social norms, safe hormonal
contraception for men could soon be available
A birth control pill for men -- the idea has
seemed like a futuristic vision. Now, with
a shift in society's attitudes and a greater
understanding of the male reproductive system,
it could soon be a reality.
"We are close to having a hormonal regimen
that might work for male contraception,"
says Diana Blithe, director of male contraceptive
research at the National Institute of Child
Health and Human Development in Bethesda, Md.
"The trick is to find the right combination
of hormones that will completely shut down
There's definitely a need for a male pill --
or a cream or injection -- especially in developing
countries with high birthrates where polls
show that up to half of pregnancies are unplanned,
says Dr. William J. Bremner, director of the
Center for Research in Reproduction and Contraception
at the University of Washington in Seattle.
Men account for about a third of contraceptive
use in the U.S., and about 10% among married
couples worldwide. Yet male contraceptive methods
have significant drawbacks. Condoms interfere
with sensation and can break, resulting in
pregnancies about 15% of the time, and vasectomies
require surgery and are usually irreversible,
rendering a man sterile.
Still, it's been daunting devising a hormonal
male contraceptive that is as safe, effective
and convenient as women's birth control pills,
which have been available since the 1960s.
To prevent a woman from becoming pregnant,
only one egg per month must be thwarted. In
contrast, "men produce a thousand sperm
every time their heart beats," Bremner
In the last decade, scientists have discovered
hormonal methods of temporarily halting sperm
production that don't interfere with other
bodily functions. Recent surveys also indicate
there is more acceptance of the notion of a
male pill and that men are more comfortable
talking about their reproductive health.
"Male sexuality is no longer the butt of
jokes or a societal taboo," says Dr. John
Amory, a scientist at the University of Washington's
Center for Research in Reproduction and Contraception.
"And because of the phenomenal success
of Viagra, drug companies are more willing
to bankroll research."
Scientists in Seattle and in Europe are testing
a combination regimen that stops the chemical
events that prompts sperm production. In a
University of Washington study, 60 volunteers
received injections of progestin, a synthetic
form of the female sex hormone progesterone.
Progestin acts on the pituitary gland in the
brain and reduces the production of two hormones
that signal the testes to make sperm.
However, progestin also decreases testosterone,
the male sex hormone necessary for libido and
secondary sexual characteristics such as muscle
bulk. So volunteers rub a testosterone gel
on their shoulders every day to maintain levels
of this crucial hormone.
Preliminary results have been encouraging. After
three or four months, sperm counts dropped
to zero in the majority of test subjects, Amory
says, though the final results won't be available
until late next year. The researchers hope
to achieve an overall efficacy rate of about
95%, which is comparable to female contraceptive
Drug companies and university researchers alike
are searching for ways to deliver the hormones
in pill form. The European trial, which is
being conducted by Schering of Germany and
the Dutch drug maker Organon, uses the same
strategy to suppress sperm but a different
delivery method. The study began in January
and involves 350 volunteers who have a 1.6-inch
implant in their arm that contains progestin;
they also receive testosterone injections every
three months. Researchers hope to have results
Although it will be at least five years before
a male hormonal contraceptive is available
in the U.S., Bremner says, the Organon/Schering
implant could be approved much sooner in Europe.
Multiple approaches to male birth control
Scientists around the world are studying various
types of birth control for men.
Chinese scientists are working on a hormonal
method that relies most heavily on the male
hormone testosterone instead of the female
hormone progestin. In a clinical trial in its
final stages, 1,000 men received monthly injections
of highly concentrated testosterone to turn
off sperm production.
An earlier test indicated the injections dropped
sperm count to zero or close to it in 296 of
Studies of non-hormonal approaches aren't as
far along. Researchers at the University of
North Carolina School of Medicine in Chapel
Hill, for instance, have discovered an enzyme
in sperm that is necessary for sperm movement
and that could be used to develop future contraceptives.
Mice bred without this enzyme produce sperm
that can't swim toward egg cells to fertilize
British researchers at Oxford University recently
found that a drug used to treat a condition
called Gaucher disease makes the sperm in male
mice abnormal, rendering them sterile. That
too could ultimately lead to other methods.
<< Los Angeles Times -- 12/6/04 >>
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