Yesterday the FDA approved Flibanserin, to be sold as Addyi, to treat low sexual desire in women. The media, likely taking cues from the drug’s maker Sprout Pharmaceuticals and women’s rights groups, have dubbed the drug the “female Viagra,” an oddly inaccurate nickname that seems to have stuck. The medical community has in turn argued that Flibanserin is anything but the female Viagra, given several factors, not the least of which is the organ that it targets – the brain, rather than the genitals. Beyond this, its relatively low efficacy, high risk of side effects (especially when taken with alcohol) and lack of knowledge about how it works has given some experts pause. For women who are trying to decide whether the benefits will outweigh the risks, they’ll certainly have their work cut out for them, as they sift through the hype to get to the science.
Sprout Pharmaceuticals CEO Cindy Whitehead holds a bottle for the female sex-drive drug Addyi at her Raleigh, N.C., office on Tuesday, Aug. 15, 2015. After two rejections, the U.S. Food and Drug Administration gave approval Tuesday for the drug, also known as flibanserin, as a treatment for hypoactive sexual desire disorder, a first for women. (AP Photo/Allen G. Breed)
One positive aspect of the drug’s approval that few dispute is the significance of the fact that a sex drug for women was approved at all. “The Flibanserin approval is a landmark moment,” says Kim Wallen , sex researcher and professor of psychology and behavioral neuroendocrinology at Emory University. “Not because it is an effective or necessarily a safe drug,” he adds, “but because it is the first time, to my knowledge, that a drug has been approved strictly to improve sexual desire. Contrary to Sprout’s lobbying effort, there have been no drugs that directly addressed sexual desire for either men or women. This legitimizes sexual desire as an important part of women’s lives and justifies treatment for low desire if the woman is interested in increasing her sexual desire. This is a real sea change in thinking about sex and drugs.”
But that’s where the accolades end. The reality is that Addyi and Viagra are only vaguely related – they both fall under the general umbrella of “sex,” but that’s about it. Viagra treats erectile dysfunction (ED) by affecting the mechanics of sex, relaxing the blood vessels of the penis so that an erection can occur. Addyi, or Flibanserin, works on the brain, under the auspices of targeting sexual desire in the first place – but it’s more closely related to antidepressants than to ED drugs. “Viagra does not affect sexual motivation,” says Wallen, “except for the effect that a man with erectile dysfunction may be more interested in sex if he knows that he can reliably get an erection… Flibanserin is not the female Viagra and the constant use of this term reflects that few understand what it is that Viagra does and why Flibanserin is so different.”
In fact, we really don’t know not only how or why the drug would work, but we also don’t know enough about how the neurobiology of sexual desire works to design a drug to address it. “We know that hormones have something to do with it as in both men and women when they lose gonadal function desire generally lose sexual desire,” says Wallen, “but we also know that many other non-biological factors influence desire – pay raises, vacations, a new partner. In general these non-biological factors produce more profound effects than do any of the proposed biological treatments. The reason that Flibanserin is so marginally effective is that no one actually knows what could work or why it would work.”
The drug was rejected by the FDA once in 2010 and again in 2013, citing ineffectiveness and a too-high risk for side effects. Now approved, after much lobbying from Sprout and women’s groups like “Even the Score,” the drug still carries strong warnings, namely of episodes of extreme low blood pressure and syncope (fainting), especially when taken with alcohol. In fact, doctors are strongly urged to talk with their patients about the seriousness of that contraindication – which may be a big consideration for some women who enjoy an occasional drink, since the drug is taken every day, not just on an “as needed” basis like Viagra.
And perhaps the bigger concern is the ho-hum efficacy the drug seems to have. In clinical trials, somewhere between 9% and 14% of women taking the drug responded to it. And these women had on average an increase of 0.5 to 0.7 “sexually satisfying events” per month compared to placebo. That doesn’t sound like much. That said, my colleague David Kroll points out that if even 10% of women respond to the drug, of the 16 million women who are thought to have low sexual desire, that would mean that 1.6 million might be helped. But whether the benefits outweigh the risks when you’re talking about having one extra ”sexually satisfying event” per month is unclear.
“Looking at Flibanserin on its merits, it does not appear to be a very effective drug,” says Wallen. “A majority of Flibanserin’s effect appears to be due to a very large placebo effect. Were Sprout to market the placebo they would have a drug as effective as the active compound with no safety concerns. Of course, the FDA won’t approve a placebo, but it is striking how large is the placebo effect. I suspect that this means that many women who take the drug will initially notice a change, but that after 3 months, or 6 months, or a year they will notice that their libido is right back where it started.”
Part of the problem is that researchers can’t seem to agree on what sexual desire is in the first place, let alone how it works in the brain. Some sex researchers feel that all female sexual desire is reactive – a response what’s happening around them – rather than a something that can just exist on its own. “In their view, what Flibanserin supposedly treats, lack of spontaneous sexual desire, doesn’t exist.” Wallen adds that he disagrees with this theory, and believes, as do the makers of Addyi, that there’s also a state of desire, which we call “horniness.” But because so much of sexual desire is based on context and other psychosocial factors, focusing on these elements, he says, has more promise than focusing on a biological system that we don’t really understand.
“In my view, if context can change desire then at some biological level it is changing the expression of the biological mechanism that creates desire,” says Wallen, “but what that mechanism is I have no clue, and neither does any pharmaceutical company. Of course I suspect Sprout could care less. Their goal is not to treat low sexual desire, but to make lots of money and in that they are very likely to succeed. They will get rich leaving many disappointed women in their wake.”
Finally, there’s a psychological element to the issue that’s not been mentioned so much: How it will affect the relationship between the women who’s considering taking it and her partner. Wallen points out that an unexpected consequence of Viagra was that it destabilized some of the couples who had adjusted to the man’s ED. In some cases, he says, “the return of male erectile capacity was desired by the man, but not the woman, and increased sexual pressure on women in relationships where sex had become a smaller part of that relationship. In the case of Flibanserin, I wonder who will be the one desiring that the women take the drug. Will they all be women seeking to increase their interest in sex, or will it be husbands pressuring their partner to increase their wife’s sexual desire? The drug was created to address very low sexual desire. What will be the incidence of women with typical libido being pressured into getting this drug to enhance their desire? I wonder how this will change the dynamics of couples.”
So does it really “even the score,” as the women’s groups have pushed at so hard? It’s certainly not clear at this moment in time. You could even argue that it make the score more disparate, since Sprout and its fans are celebrating a drug with low efficacy, significant side effects, and a poorly understood mechanism of action. But for the small portion of women it does help, perhaps it will make a difference. And perhaps its very existence will prompt more research into the area of sexual desire – at present, the National Institute of Mental Health doesn’t fund research like this because it doesn’t consider the issue a mental health issue. “If Flibanserin does open the doors to research in sexual desire then it will serve a very valuable purpose,” says Wallen. “I fear, though, because of its ineffectiveness that it will eventually be seen as a drug that didn’t work and that will be the end of the story. I hope I am wrong.”
