That may be changing.
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The Lincolnshire, Ill.,-based company is conducting two trials, comprising 1,000 women, to test the effectiveness of the gel, which is applied to the upper arm. The company will also test the gel's safety in a trial of as many as 3,100 women using LibiGel or a placebo.
If the trials go well, the drug could be available by prescription by 2011, says BioSante chief executive Stephen Simes.
A testosterone gel for menopausal women makes sense medically, says Dr. Richard Paulson, professor of reproductive medicine and chief of reproductive endocrinology at USC's Keck School of Medicine.
Both men and women produce the female hormone estradiol and the male hormone testosterone, but in different quantities. When women go through menopause, they lose almost all of their estradiol production and most of their testosterone production. Estrogen (either taken orally or topically applied) helps keep the vaginal tissue strong and elastic, but it doesn't enhance libido.
A testosterone gel, Paulsen says, could restore libido and reestablish the pre-menopausal balance between testosterone and estradiol. It could be especially beneficial to women who have had their ovaries surgically removed and lose even the small amounts of testosterone that ovaries produce after menopause. This population "is particularly susceptible to symptoms attributable to the loss of hormone production, such as hot flashes and loss of libido," he says.
Currently, the only option postmenopausal women have for boosting testosterone is off-label use of products developed for men, says Sheryl Kingsberg, chief of Behavioral Medicine at University Hospitals Case Medical Center in Cleveland, Ohio. "We know that it works -- not for everybody -- but it works," she says. "And we know that about 20% of all prescriptions for testosterone are for women."
But safety, particularly the possibility that testosterone could increase the risk of breast cancer, is still a concern. "We haven't seen serious adverse effects" from use, says Kingsberg, a psychologist and sex researcher, "but we need more data."
The first LibiGel trial was launched in December 2006. About 500 healthy women ages 30 to 65 across the U.S. and Canada who had had their ovaries removed and reported distress over low libido applied LibiGel or a placebo for 24 weeks. Using diaries and questionnaires as measurements, the women documented quantity and quality of sexual events, including intercourse, oral sex and masturbation.
Following treatment, the women using LibiGel reported a significantly increased number of satisfying sexual events compared with baseline measures and compared with the placebo group. Participants reported no serious adverse effects. A second, identical trial will begin in the spring to ensure that the findings can be replicated.
The data have been presented at meetings of the International Society for the Study of Women's Sexual Health and North American Menopause Society.
A third, 12-month study will track cardiovascular events, such as heart attack and stroke, among women taking the drug, and compare them with those of a control group. Participants will be surgically or naturally menopausal women at least 50 years of age, with at least one cardiovascular risk factor, such as hypertension or diabetes.
"The FDA is asking us to study the safety in potentially a higher-risk population in order to prove that, in fact, testosterone is safe for all women," Simes says.
The study will also track the women for breast cancer for an additional four years.
Side effects associated with excessive testosterone in women include oily skin and hair growth in undesirable places, including the face and chest.
Paulson cautions that anyone hoping for an elixir of love is in for a disappointment. "Western society is replete with stories of magical potions that will cause women to become sexually ravenous," he says. "These stories of course are nonsense."
Human sexuality is complex, he adds, and testosterone level is only a small part of the overall picture. "For people who think that they are going to be able to sneak it onto their date's arm while she's not looking -- they should forget it."