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FDA
Approves Gel to Treat Low Testosterone Levels
AndroGel May Be Easier to Use Than Other Therapies |
By Ashley Manos
WebMD Medical News
The FDA this week approved the first testosterone
gel for treatment of men with low testosterone levels.
The gel, called AndroGel, is applied once daily
to the shoulders, upper arm, and/or abdomen.
"This is a quite convenient way of delivering
testosterone in a dose-related fashion. The more
you put on, the higher the testosterone," Ronald
S. Swerdloff, MD, tells WebMD. Swerdloff is chief
and professor of medicine, division of endocrinology,
at Harbor-UCLA Medical Center in Los Angeles. He
was the lead investigator of AndroGel on behalf
of the manufacturer, Unimed Pharmaceuticals Inc.
"The testosterone gel has several advantages
over the [currently] available delivery systems,"
Swerdloff says. Unlike injections, the gel does
not cause discomfort, and it provides a constant
level of testosterone. The oral versions of testosterone
are synthetic and may be damaging to the liver,
while transdermal patches often have problems with
adhesiveness.
Testosterone, one of a class of hormones known
as androgens, is responsible for the development
of the male sex organs and for the maintenance of
secondary sex characteristics, including development
of facial and pubic hair, vocal cord thickening,
and alterations of body musculature. Low testosterone,
a condition called hypogonadism, affects approximately
4-5million American men and is linked to diminished
interest in sex, impotence, reduced lean body mass,
decreased bone density, and lowered mood and energy
levels.
AndroGel is a colorless gel containing 1% testosterone.
It is applied daily to clean, dry skin; the gel
dries within a few minutes and is absorbed into
the skin, which serves as a reservoir, providing
sustained delivery to the bloodstream for up to
24 hours. After applying the gel, patients should
immediately wash their hands to avoid exposing others
to the medication. The gel should not be used on
women, and pregnant women should avoid contact with
the application sites of the gel on men, as it could
harm the fetus.
In the female partners of men using AndroGel, 15
minutes of vigorous skin-to-skin contact increased
testosterone in the women to twice their ordinary
levels. When a shirt was worn to cover the gel-application
site, transfer of testosterone to the women was
prevented.
"In none of the partners of the individuals
who were treated with testosterone were there any
significant clinical problems," Swerdloff tell
WebMD. "Because there is a potential for testosterone
transfer, the recommendation is that patients shower
before intimate contact or wear a shirt over the
area to which the drug is applied. The testosterone
is driven into the skin, so showering doesn't alter
the effectiveness of the testosterone."
To assess the effectiveness of AndroGel, researchers
studied 227 men with low testosterone levels. The
men received either AndroGel in varying doses, or
testosterone through a skin-patch delivery system.
After 60 days, their blood levels of testosterone
were checked and the doses were adjusted. Of the
129 men who were appropriately adjusted, 87% achieved
normal levels of testosterone that were maintained
for the remaining three months of the trial. In
this and other trials, side effects were moderate
but infrequent -- mostly skin reactions to the gel,
including acne; prostate and urinary problems; and
swelling.
"We were able to put the testosterone into
the normal blood range in the majority of the people.
It's simply a matter of adjusting the amount of
gel that's applied. So everybody could be treated
once a proper dosage [is] determined," Swerdloff
says. The manufacturer recommends checking the blood
two weeks after starting.
"The positive effects were on sexual drive
and on mood," Swerdloff says. "People
had less depressive symptoms. There was an improvement
in the lean body mass and muscle strength. ... It
was surprising to us that within six months of treatment,
there was a significant increase of bone mineral
density."
Swerdloff tells WebMD that there are many potential
applications for testosterone. It is being studied
in combination with other hormones as a male contraceptive.
Many researchers are looking at giving androgen
replacement therapy in men over 65. Testosterone
may also one day be used in women to improve libido,
or added to conventional hormonal therapy to help
improve bone mineral density. AndroGel is only approved
for men and has not been studied in those over age
65.
Androgens are not recommended for men with breast
cancer or known or suspected prostate cancer. Androgens
may increase the risk of developing enlarged prostates
and prostate cancer.
According to Unimed, AndroGel will be available
by midsummer. The price has not yet been determined.
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