Flibanserin is being touted as a drug designed to boost the low sexual desire of otherwise healthy women. Here's how it works and why it's really not like Viagra at all. (The Washington Post)

What exactly is ‘female Viagra’?

The drug the FDA approved Tuesday, flibanserin, is the world's first drug designed to boost a woman's sexual desire. While it’s become commonly known as ‘female Viagra,’ it's intended to work in an entirely different way. Whereas Viagra treats erectile dysfunction by increasing blood flow to the penis, flibaserin is aimed at increasing a woman's libido by balancing levels of serotonin and dopamine in the brain.

[From 1952-2015: The path to 'female Viagra' has been a rocky one]

What is it designed to treat?

Flibanserin is intended to help women experiencing Hypoactive Sexual Desire Disorder (HSDD), or low sexual drive. A 2008 study published in the journal Obstetrics & Gynecology, estimates that 1 in 10 women suffer from low sexual desire that is not related to any other biological, psychological or environmental condition or drug interaction. People with HSDD often say they love their partner and want physical intimacy, but simply have lost their desire for sex due to improper brain chemistry.

Does it work? And is it safe?

That depends on who you ask. The FDA has twice rejected flibanserin, once in 2010 and again in 2013, saying that common side effects such as fainting, nausea, dizziness and low blood pressure outweighed the uncertain benefits of the drug.

[FDA approves controversial ‘female Viagra’ drug]

The drug's North Carolina-based manufacturer, Sprout Pharmaceuticals, resubmitted an application for approval this year, along with additional safety studies. In June, an FDA advisory committee voted 18-6 to recommend that the FDA approve flibanserin, with certain conditions, such as warning labels against using the drug with alcohol, some birth control pills and certain anti-fungal medications. Even then, the committee described the drug's benefit as "moderate" or "marginal."

Critics have dismissed flibanserin as unproven and overhyped. They point out that the drug has very clear adverse side effects, like sleepiness, dizziness, nausea, even fainting, which apparently can be worsened when combined with alcohol, while providing only middling results in treating low female sex drive.

They also have criticized the push for the treatment as little more than a marketing ploy. Writing in a scientific journal in 2006, one American psychologist said "the creation and promotion" of female sexual dysfunction was "a textbook case of disease mongering by the pharmaceutical industry and by other agents of medicalization."

Some panel members who voted against approval in June said that the data simply wasn't strong enough to warrant approval. "I recognize people are suffering," Diane Aronson said at the time. "I just think they deserve better."

If the FDA has rejected it in the past, why would the agency approve it now?

For starters, Sprout Pharmaceuticals showed up at the FDA meeting in June with results from double-blind clinical trials showing the drug worked better than a placebo to boost women’s sexual desire. The company argued that after 24 weeks, as many as 60 percent of the women in the trials had benefited from flibanserin (though some committee members said after adjusting the data to account for the placebo effect, the drug helped only about 10 percent of the women in the trials.)

Still, it's tough to overstate the public pressure the FDA has received in the lead up to its latest decision. The recent advisory committee meeting included emotional testimony from women who suffer from low sex drive. One practitioner said when female patients suffering from sexual dysfunction ask her for help,"This is all I can tell them." She stood in front of the microphone in silence for several uncomfortable minutes to demonstrate her point.

[The fight for a 'female Viagra']

The Even the Score campaign supported by Sprout essentially has accused the FDA of being sexist -- a charge FDA officials publicly denied -- given its approval of multiple drugs to treat sexual dysfunction in men, but not a single one for the most common sexual complaint among women. "Why do we fast track the approval of drugs like Viagra (1998) for men?" reads one passage on the group's Web site. "Why do we accept fewer patients in trials for male drugs than we've seen for some for women? [Why] do we accept risks that we all hear every other Superbowl commercial for men but question what benefit is worth risk for women?"

Given the lack of treatments for women with lack of libido, a key question for the FDA was whether it ought to allow flibanserin on the market, despite its modest benefits and numerous side effects.

"It's hard to imagine that the advocacy campaign wasn't influential in some way shaping the outcome," said Caleb Alexander, co-director of the Johns Hopkins Center for Drug Safety and Effectiveness and FDA panel member who voted against recommending approval for the drug.

What comes next?

Sprout says the potential market for flibanserin could include 16 million women. The company eventually hopes to win expanded FDA approval for the drug to market it to menopausal and post-menopausal women, further expanding its reach.

[FDA advisory panel recommends approval of 'female Viagra']

Already, about 2 million women receive off-label testosterone treatments for HSDD, which has whetted other drug makers' appetites about the potential size of the market. Several other drugs for the condition are in various stages of development, and some drug researchers say the FDA's approval of flibanserin will only spur more investment in drugs to treat low female sex drive.


In this June 22, 2015, photo, a tablet of flibanserin sits on a brochure for Sprout Pharmaceuticals in the company's Raleigh, N.C., headquarters. Sprout soon may succeed where many of the world’s largest pharmaceutical companies have failed: in winning Food and Drug Administration approval for flibanserin, dubbed Addyi, the first drug to boost women’s sexual desire. (AP Photo/Allen G. Breed)

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