WASHINGTON (AP) -- A hormone patch that works to restore a woman's sex drive should not be approved until additional studies to determine its risk, federal health advisers said Thursday.
The advisers said they were unimpressed with the number of women studied so far as well as the length of the studies.
Procter & Gamble hopes to market the testosterone patch Intrinsa to women whose ovaries have been removed and who have lost their libido. The company told the Food and Drug Administration advisory committee that the drug had not raised safety concerns in clinical trials, and it urged the panel not to delay approval of the first drug for female sexual dysfunction.
However, the advisory committee was unanimous in saying more safety data were needed.
The company told the panel that women who tried the patch in clinical trials had improvements in sexual arousal and orgasms and had more satisfying sexual experiences.
FDA staff members, however, said benefits were modest and accompanied by concerns about health risks involving testosterone use.
Agency officials noted a lack of controlled safety data for women who had used Intrinsa longer than six months.
The panel heard testimony that three of four women who developed breast cancer during the clinical trials were using Intrinsa.
Lisa Soule, a medical officer in FDA's division of reproductive and urological drugs, said those breast cancer cases pointed to the limitations of short-term clinical trials.
Soule dismissed as inadequate Procter & Gamble's suggested postmarketing study comparing 5,500 women expected to use Intrinsa in the first year against a database of 10 million patients for rates of cancer and cardiovascular disease.
A federally funded research project, by contrast, had to enroll nearly 17,000 postmenopausal women to begin to detect the safety problems with hormonal therapy, Soule said.
"It is not uncommon to have unanswered safety questions at approval," said Joan Meyer, senior director of new drug development for Procter & Gamble.
Meyer told the panel the company will soon have more safety data adding information for nearly 200 women who have used the patch for one year.
The company will also provide safety data on 100 more women who have used the patch for 18 months. Eighty women have been using the product for three years.
The federal advisers' recommendations will go to the FDA, which is not bound by the recommendation but usually follows it.
Although the drug is sometimes referred to as a female Viagra, it actually works differently from the drug for male sexual dysfunction. Viagra works to enhance a man's ability to have sex; Intrinsa increases a woman's desire for it.
Removal of ovaries can cause women's testosterone levels to drop by 50 percent.