US authorities are pouring cold water on hopes for a new drug to treat women with low sexual desire.
The Food and Drug Administration (FDA) wants more studies to be done on the Intrinsa patch made by Procter & Gamble in order to find out what long-term side effects the drug may induce, the Los Angeles Times reported.
Intrinsa has been called "female Viagra" as it promises to restore healthy sexual appetites to women struggling with low desire.
Though experts say female sexuality is more complex than male, and affected more deeply by mood, self-esteem and the relationship, new studies of Intrinsa showed that the drug boosts desire by delivering small doses of testosterone through a woman's skin, thereby boosting the level of the male sex hormone in the bloodstream.
According to some estimates, the drug could help 11 million US women who are thought to suffer from a condition known in medical circles as hypoactive sexual desire disorder, or HSDD.
But though it took only six months for the FDA to approve Viagra for enhancing male libido, there is no approval in sight for the female version.
Acknowledging the "huge demand" that would probably come with approval, panel members worried aloud that long-term use by millions of women might increase the rates of breast cancer, heart disease and stroke.
The concerns were increased by the belated recognition that hormone replacement therapy, used for years to soften the effects of menopause, was linked to a significant increase in heart disease, breast cancer and strokes.
The cautious approach is also because of mounting concern over long-term safety of new drugs prompted by the discovery last December of the potentially fatal side effects associated with the anti-arthritis drug Vioxx.
Last December, just weeks after Vioxx was pulled from the market for safety concerns, an FDA panel gave the testosterone patch - made by Procter & Gamble - the equivalent of a blinking red light.
Thus the FDA wants extensive five-year clinical trials involving thousands of women.
Even two recent studies that indicated that Intrinsa significantly helped women and led to an increase in "satisfying sexual events" is unlikely to change the mind of the FDA as it is set for a review of the drug, according to the report.
One study published last week in the Archives of Internal Medicine found that women who used the patch for 24 weeks reported, on average, a 67 percent increase in their sexual desire, compared with a 48 percent increase in desire reported by women taking a placebo, or dummy pill.
It also boosted the number of "satisfying sexual encounters" from an average of three per month to about five.
A similar finding was reported in May by researchers at Baylor Medical College.
The issue has sparked a debate in the medical world, with some experts applauding the FDA for its cautious approach and others charging it with setting a higher standard of safety for drugs designed to increase female sexuality.
Procter & Gamble remained confident that the hurdles could be overcome.
"We're in talks with the FDA, working out a practical approach to address their concerns about safety," said spokeswoman Elaine Plummer, adding that no studies to date have suggested serious negative effects.
Medindia on Viagra:
ViagraTM is the first approved non-surgical treatment for erectile dysfunction that does not have to be either injected or inserted directly into the penis to achieve and maintain erection. The US Food and Drug Administration (FDA) approved it for prescription sale at the end of March 1998. Viagra does not directly cause penile erection, but affects the response to sexual stimulation.
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