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In this Oct. 30, 2007 file photo, employees are silhouetted at the Boehringer Ingelheim pharmaceutical factory in Ingelheim, central Germany. Boehringer Ingelheim has asked the Food and Drug Administration to approve its drug flibanserin for women who report a lack of sexual desire, a market that drugmakers have been targeting for more than a decade since the success of Viagra in men. Federal health regulators said Wednesday, June 16, 2010, the first pill designed to boost the female sex drive failed to make a significant impact on libido in two studies.Michael Probst/The Associated Press

Today was a historic day for women – well, for the approximately 10 per cent of women who experience distressing loss of sexual desire.

Since Viagra was approved in 1998, drug companies have been racing to be the first to create a drug for women's sexual dysfunction. And contrary to many experts' predictions that testosterone would be the first approved medication, it is actually a failed antidepressant, flibanserin, to cross the victory line. (But only in America. Canadian women will have to wait for Health Canada to study the drug.)

Flibanserin is a daily pill that selectively acts on serotonin receptors (5-HT1A receptor agonist and 5-HT2A receptor antagonist to be exact). A decade ago, it was tested for use in patients with a major depressive disorder. But while it wasn't an effective antidepressant, patients in the study did report an improvement in sexual desire. So Boehringer Ingelheim, the pharmaceutical company, switched gears and focused on its potential libido-enhancing properties.

In fact, Boehringer Ingelheim was sufficiently impressed with flibanserin's positive effects in women with hypoactive sexual desire disorder (a distressing lack of desire for sexual activity and low or absent sexual fantasies) that they submitted an application for approval to the U.S. Food and Drug Administration (FDA).

The FDA did not share the pharmaceutical company's enthusiasm, and a panel unanimously voted against flibanserin's approval due to only marginally better effects compared to the placebo group. It was also concerned about its safety, particularily its sedating effects and dizziness that make users a driving risk.

Boehringer Ingelheim then sold the rights to flibanserin to Sprout Pharmaceuticals, who tested flibanserin in more women, this time examining women's sexual desire as well as the frequency of their "sexually satisfying events" per month, and pitched their case to the FDA in 2013. Again not sufficiently impressed by the improvements compared to placebo, and concerned with the significant side-effects of the drug, the FDA rejected flibanserin for the second time.

A slick advertising campaign and online petition supported by non-profit patient advocates and two drug companies ( accused the FDA of sexism (it approved 26 medications for the treatment of men's sexual dysfunction and zero for women), gave Sprout the momentum it needed to focus on satisfying the FDAs remaining concerns.

New research specifically examining contraindications with alcohol, as well as risks while driving were carried out.

At the opening of Thursday's hearing, Dr. Hylton Joffe, director of the FDA's Division of Bone, Reproductive and Urologic Products addressed the accusations of gender bias head-on, stating that FDA decisions are based on benefits versus risk, and that gender is not taken into consideration.

After Sprout presented its findings – based on 11,000 women in monogamous, heterosexual relationships who had developed distressing low sexual desire, but who continued to experience two to three sexually satisfying events per month – an FDA advisory board voted 18 to six in favour of the regulator considering its approval for premenopausal women.

However, there were hefty concerns and no one voted in favour of using package labelling alone to address the risks of flibanserin.

The most common side-effects were dizziness, drowsiness, nausea, fatigue, insomnia and dry mouth, though representatives from Sprout argued that the rate of these side-effects was no different from other brain-acting medications, and certainly not strong enough to override the benefits of a drug to address "a serious unmet medical need."

The advisory board unanimously urged that a serious warning about the risks be discussed with patients, including an outright ban on mixing the drug with alcohol until further studies are completed that directly address flibanserin-alcohol interactions in women (the Sprout-funded study included mostly men). It also recommended that physicians prescribing flibanserin receive special training and certification, though how this will be monitored over the long-term is unclear.

Some on the advisory panel recommended that women be tested every three months for potentially serious side-effects. It also stated that physicians should only offer flibanserin to premenopausal women in partnered heterosexual relationships, who were not using alcohol and who once experienced sexual desire, but no longer do, and continued to engage in regular satisfying sex.

To many sex therapists, however, this is an ideal outcome of an effective treatment. It raises many doubts about who actually participated in the flibanserin clinical trials.

Is there a risk of off-label prescribing to women who do not fit into that category? Yes, and the potential risk is difficult to anticipate, in the same way that Viagra was used for reasons that it was not originally intended . However, with flibanserin approved, it may be easier for independent sex scientists to study the drug, and how it fares against sex therapy, both alone and in combination. Scientists with no commercial interests in Sprout Pharmaceuticals or flibanserin should be testing how well it works and how safe it is.

I do not believe that flibanserin will cure all women of low desire, though I do think it may help a small group of women whose loss of sexual desire is unrelated to mood, stress, relationship factors, contextual inhibitors or sociocultural causes.

It may help to restore feelings of spontaneous desire among those who are unable to point their finger on another cause. Flibanserin will not make a woman more attracted to her partner, challenge her negative self-image or make her feel more well-rested after five hours of sleep. I expect that good sex therapists will remain busy addressing these other forces that stomp out desire for women.

The FDA will consider the advisory panel's overall positive vote and make a recommendation by the end of summer. I predict that flibanserin, under its trade name, Addyi, will hit pharmacies and women's bedrooms shortly thereafter.

Health Advisor contributors share their knowledge in fields ranging from fitness to psychology, pediatrics to aging.

Lori Brotto is an associate professor of gynecology at the University of British Columbia and a registered psychologist. You can find her at and follow her on Twitter @DrLoriBrotto.

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