Five Studies: Does Flibanserin Provide Real Sexual Benefits for Women?

Research suggests that the now-FDA-approved female libido-booster is—at least in part—a pharmaceutical ploy.
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If there’s one thing everyone can agree on, it’s that there’s only one right way to have sex. Since human culture began, authorities have told other people how to do it, when to do it, and with whom to do it—and, now that the Food and Drug Administration has approved Addyi, even how much to want it.

On August 18th, the FDA announced that it had approved Addyi as the first-ever treatment for acquired, generalized hypoactive sexual desire disorder (HSDD) in pre-menopausal women. Notably, hypoactive sexual desire disorder was described in the DSM IV, psychiatry’s manual of mental disorders, but the diagnosis was eliminated in DSM V and is now known as “female sexual interest/arousal disorder.” Since 2013, when DSM V was published, hypoactive sexual desire disorder has been a non-existent diagnosis; but Addyi has soldiered on to FDA approval.

Addyi, or flibanserin, was developed as an anti-depressant but failed to show benefits among trial users. The company behind it, Boehringer Ingelheim, changed tactics and tested it as a treatment for hypoactive sexual desire disorder. Though it was rejected three times by the FDA, it will finally be brought to market thanks to persistent pressure from Sprout Pharmaceuticals, which bought flibanserin, and from women’s groups, which Sprout enlisted for support. The International Society for the Study of Women’s Sexual Health announced the “historic event” on its website, “with tremendous excitement,” apparently without irony.

The ISSWSH’s press release was co-signed by its president and advocacy chair, both consultants to Sprout Pharmaceuticals.

Just what is female sexual interest/arousal disorder, and is it a real problem for some women? The criteria for diagnosis include low interest in sex, decreased “receptivity” to a partner’s advances, and decreased erotic fantasies. The loss of interest must have lasted for at least six months, and must cause “clinically significant distress”—meaning that if you don’t care that you’re not interested, it’s not a disorder. If you do care, now we have flibanserin. Here are five studies that tell you what you need to know about this new drug.

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FLIBANSERIN WORKS BY ENHANCING DOPAMINE RELEASE WHILE INHIBITING RELEASE OF SEROTONIN

Neuroscientists recognize that the release of dopamine and norepinephrine in the brain are essential for experiencing pleasure, sexual and otherwise. Rewarding stimuli—food, social interactions, certain recreational drugs—create a buzz by triggering release of these neurotransmitters in key “reward centers” in the brain. On the other hand, serotonin release in the wrong place at the wrong time decreases sexual interest and pleasure—a notorious side effect of pro-serotonin anti-depressants like Prozac and Zoloft.

Flibanserin is believed to enhance dopamine and norepinephrine release while inhibiting release of serotonin, resulting in greater desire for rewarding activities, including sex.

Stephen M. Stahl. "Mechanism of Action of Flibanserin a Multifunctional Serotonin Agonist and Antagonist (MSSA), in Hypoactive Sexual Desire Disorder," Stahl, S., CNS Spectrums, 2015.

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AND IT HAS RELIABLY POSITIVE—IF UNDRAMATIC—OUTCOMES

The pharmaceutical companies that developed flibanserin conducted placebo-controlled trials of it in HSDD. Lest anyone confuse sexual desire in women with anything indelicate, all the trials were named after flowers: VIOLET, BEGONIA, and DAISY for pre-menopausal women, and SNOWDROP for post-menopausal elders. The trial found a trend among outcomes: Women achieved an average of one more “satisfying sexual event” per month on flibanserin. These could include any type of genital stimulation. More than 23 percent of women on flibanserin felt that they were “very much” or “much” improved, compared with 16.2 percent on placebo. The authors found no significant safety concerns, though the FDA requires that prescribers go through special training about the risk of drinking alcohol while taking Addyi; the combination can cause dangerously low blood pressure.

"Efficacy of Flibanserin in Women With Hypoactive Sexual Desire Disorder: Results From the BEGONIA Trial," Katz, M. Et al., Journal of Sexual Medicine, 2013.

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BUT THE CRITERIA FOR CHOOSING TRIAL CANDIDATES EXCLUDES AN IMPORTANT SEGMENT OF POST-MENOPAUSAL WOMEN

The snowdrop, pushing its way up through melting snow, is a harbinger of spring. It also calls to mind a white-haired, bent-necked old lady pushing a walker through the slush. So it’s the perfect flower to represent the post-menopausal woman with HSDD. while the SNOWDROP trial’s results were remarkably similar to BEGONIA’s, SNOWDROP is perhaps most interesting for its exclusion criteria. Women were excluded if they had “a history of a serious clinical disorder,” pelvic surgery such as hysterectomy, pelvic pain, endometriosis, urinary tract infection, or vaginal atrophy, or were taking medications such as any anti-depressants, benzodiazepines (anti-anxiety medications), prescription sleep aids, mood-stabilizers, anti-convulsants, and narcotics, among many others. The study required that women be monogamous, heterosexual, in a relationship for over a year, and have a sexually functioning partner who would be available for sexual activity for 50 percent or more of every month. Unsurprisingly, almost half the women screened for the study were not eligible to participate. The exclusions were an attempt to isolate HSDD from other conditions that could cause sexual dysfunction, but they resulted in a study population far from representative of older women who wish to be more sexually active.

James A. Simon, J. et.al., "Efficacy and Safety of Flibanserin in Postmenopausal Women With Hypoactive Sexual Desire Disorder: Results of the SNOWDROP Trial," Menopause, 2013.

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AND NEUROTRANSMITTERS ARE HARDLY THE ONLY REASON THAT PASSION CAN WANE

Psychologists asked married women to talk about diminished sexual desire, and they didn’t hear a word about neurotransmitters. One theme was the oppressive “institutionalization of the relationship,” i.e. feeling less erotic because the husband had already been won. Another theme, “over-familiarity,” included complaints about boring sex, orgasm-focused sex, lack of romance, and decreased feelings of attractiveness, and of attraction to one’s partner. Finally, “de-sexualized roles” referred to how lists of chores, shopping needs, and child care preoccupy many women during sexual activity. The researchers noted that all the women they interviewed had characterized their relationships as positive, and loved their partners. The popular idea that women’s sexual desire depends on closeness to their partners did not hold up to scrutiny. These women were close to their partners; even so, they didn’t want sex the way they used to.

"Why Did Passion Wane? A Qualitative Study of Married Women’s Attributions for Declines in Sexual Desire," Sims, K. And Meana, M., Journal of Sex and Marital Therapy, 2010.

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EVENING THE SCORE

Given the limited benefits of flibanserin, the warnings about its interactions with alcohol, and the fact that hypoactive sexual desire disorder was struck from the DSM V, you have to wonder: What was the FDA thinking? Last year, the British Medical Journal ran an editorial critical of Sprout Pharmaceutical’s opportunistic use of feminist rhetoric to gain support for its product. The “Even the Score” website exhorts women to “become an advocate for women's sexual health equity.” The campaign suggests that a lack of concern for women’s sexual needs has caused the FDA to approve multiple medications for male sexual problems while neglecting those of women, and that “sex is a basic human right.”

Hidden behind the righteousness is the fact that feminists involved in the campaign got their information from advisors paid by Sprout Pharmaceuticals. Are female consumers being sold a product as irrelevant to their well-being as the newest mascara, or are they fighting for their rights? The British Medical Journal's editors makes a convincing case that the FDA caved to bullying and manipulation on the part of Big Pharma.

"Evening the Score on Sex Drugs: Feminist Movement or Marketing Masquerade?" Moynihan, R., British Medical Journal, 2014.

Five Studies is Pacific Standard’s biweekly column that identifies and analyzes the best academic research to deliver new insights on human behavior.

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