There was a time when Wendy and her husband had sex three times a week. But for the past six years, the purple negligee that Wendy used to entice her husband has been stuffed in the back of a drawer. And now, instead of getting hot and bothered by her husband's advances, Wendy is simply bothered. "All of a sudden I didn't have any desire. There's just nothing there anymore," says Wendy, who requested that her last name not be published.
For about a decade, roughly since the FDA approved Viagra for sexual dysfunction in men, drug companies have been searching for the female version of the little blue pill, a drug to cure what ails women like Wendy in bed. But what ails them — a psychiatric condition known as hypoactive sexual desire disorder (HSDD), defined as a distressing lack of sexual desire, absent other medical conditions — has been notoriously difficult to pin down.
That doesn't keep drugmakers from trying to develop a treatment, seduced by the prospect of a multibillion-dollar blockbuster that could be even bigger than Viagra and its competitors combined. At a European conference for sexual medicine on Monday, a German pharmaceutical company presented results from a pivotal phase III clinical trial in North America and announced that it had found a drug that works. "We saw an increase in sexually satisfying events, an increase in desire and a decrease in distress. When we look at this against a backdrop of a common and distressing problem that affects 1 of 10 women and for which no treatment exists, well, we are feeling very positive," said Michael Sand, director of clinical research for Boehringer Ingelheim, which originally developed the drug, flibanserin, in the 1990s as an antidepressant. (The drug proved not to work for depression.)
Whether or not the FDA approves flibanserin to treat women's libidos, the German company's trial results have reignited a decade-long debate over the merit of the HSDD diagnosis — the most commonly diagnosed female sexual dysfunction — which some psychologists say is a made-up condition, promoted precisely for the service of moments like this: a drug-company rep at a conference on sex declaring that a treatment has been discovered.
Certainly, there may be women who will do better after taking flibanserin, says Judy Norsigian, executive director of the women's health advocacy Our Bodies Ourselves, based in Cambridge, Mass. But she thinks the diagnosis of HSDD unnecessarily medicalizes women's sexual lives. Attempting to treat low libido with a pill ignores the fact that many women's level of desire is deeply affected by everyday life stress and interpersonal relationships. Add to that a cultural milieu that at once promotes shame and ignorance about women's sexuality while wildly inflating their expectations for sex. In many cases, says Norsigian, the proper solution to a lack of sexual desire would involve a number of non-drug approaches, such as therapy, mind-body techniques and getting partners involved in the solution. "That could be equally successful while at the same time not exposing women to the [potential] long-term adverse effects of drugs," says Norsigian, who suggests testing drugs like flibanserin against drug-free therapies. "Moreover, the non-medication approaches often address root causes for lack of libido and thus reflect a prevention approach that is usually much wiser."
Yes, women are complex and so are their libidos. Which is why the quest to treat HSDD has been so fraught. It is far more difficult than, for instance, treating men's complaints about erectile dysfunction. Viagra works simply by increasing blood flow to the penis and producing an erection. In women, the issue is not about wanting to have sex and being physically unable; rather, it's often that women lose interest in sex altogether, especially with the partner who once excited them. Beyond the many and varied psychological roots of the problem, there is still much that is not known about the biological processes governing women's sexual desire.
One of researchers' best guesses so far is that women with HSDD have low levels of testosterone. Indeed, the condition affects mainly postmenopausal women or those who have had their ovaries surgically removed, which leads to a drop in sex hormones — namely testosterone. Many American women already use testosterone treatments off-label to treat their low libidos, and doctors attest that they work. But past efforts by drugmakers to get such treatments approved by the FDA specifically for HSDD have been blocked for safety concerns. Intrinsa, a testosterone patch manufactured by Procter & Gamble, is used to treat female sexual dysfunction in postmenopausal women in Europe, but after being tested in women in the U.S., the FDA rejected P&G's fast-track request for approval in 2004, requesting more long-term safety data. And early trials of the experimental compound PT-141, a nasally inhaled drug that affects brain receptors for the hormone melanocortin, which plays a role in sexual arousal, raised concerns about its effect on blood pressure. A somewhat more promising contender is LibiGel, a testosterone gel made by Illinois-based BioSante Pharmaceuticals, which is in phase III clinical trials.
Flibanserin, however, does not act on hormones, and the new data suggest that it works in premenopausal women. "We don't yet understand the pathways. What we think is that in women with HSDD, there is likely an imbalance of serotonin, and that flibanserin is balancing the imbalance in these neurotransmitters," Sand says.
The flibanserin findings are based on the study of 1,378 premenopausal women who had been in a monogamous relationship for 10 years on average. The women were randomly assigned to take 100 mg of flibanserin or a placebo daily and to record daily whether they had sex and whether it was satisfying. The women were screened for depression and other medical conditions, and all had a diagnosis of HSDD.
Women in the flibanserin group self-reported 2.8 sexually satisfying events in the four-week baseline period; in the final four weeks of the 24-week study period, those women reported 4.5 sexually satisfying events, a more than 50% increase. Women in the placebo group reported an increase from 2.7 events to 3.7. The difference in effect between flibanserin and the placebo — about 0.8 sexually satisfying events — was statistically significant, the drug company said, and the side effects from the drug, which included dizziness and fatigue, among others, were mild to moderate and transient.
It remains to be seen whether 0.8 more bouts of satisfying sex is enough to win FDA approval. In the meantime, however, Boehringer Ingelheim insists that the results shore up evidence for the neurobiological basis for HSDD, such as in women like Wendy, who says, "I am not depressed. I love my husband. Most of the time we get along great. But after our second child was born, I just lost interest in sex."
Wendy says she would take a pill to help her. But critics of such treatments worry that while a pill could potentially improve sex for some women, others may be more harmed than helped. Debby Herbenick, a sex educator and researcher at Indiana University's Kinsey Institute, does not deny that there is a biological cause of low libido. But she raises another kind of concern about drugs like flibanserin: What if they work? "[The problem] is far more complex than not desiring sex. What we really have is a group of women who wonder why they don't desire their long-term partner the way they used to," Herbenick points out. "What happens if you suddenly do have desire, but it's not for the person you hoped?"
That, of course, is not a side effect that was measured in any of the drug trials involving female sexual dysfunction — including those on flibanserin — and not one that will be weighed by the FDA.