Hopes remain high at Boehringer Ingelheim, a German drugmaker, that the Food and Drug Administration will approve the first pill to treat loss of sexual desire in women.
An FDA advisory panel is set to weigh the data in support of the drug, called flibanserin, at a meeting today. But before the meeting even got started, the odds looked long for the experimental medicine.
The pill, taken just before bedtime, hit a speed bump this week when the FDA's staff analysts gave a thumbs-down on the blockbuster-in-waiting.
The company claims up to 10 percent of premenopausal women suffer from Hypoactive Sexual Desire Disorder or HSDD, which it defines as "persistent lack of sexual desire accompanied by significant distress." That's as many as 9 million American women.
The market for BI's drug might be as large as $2 billion a year – more than the male sexual dysfunction pills Viagra, Levitra and Cialis combined.
Flibanserin was originally developed as an antidepressant. But Boehringer Ingelheim noticed the drug scored better than placebo or a competitor pill in those trials on the question "how strong is your sex drive?" That led to its repurposing as a female sex stimulant.
The company claims that its key efficacy studies, involving 5,000 women with HSDD, show that those who took flibanersin had more "satisfying sexual events" than women who took a placebo pill or no pill at all.
Incidence of adverse events "was low, with the majority…mild to moderate in severity," the company says in its 248-page presentation to the FDA.
But the FDA's analysts weren't impressed.
The flibanserin advantage on "satisfying sexual events" was slim – 4.5 a month versus 3.7 for placebo, or less than one additional episode per month on average.
FDA staffers also note that studies didn't show any improvement in women's daily reports of sexual desire. A monthly report on desire, which the company hopes the FDA will consider instead, isn't statistically valid, the analysts say.
The FDA staff also have doubts about flibanserin's safety. One of every eight women taking the drug reported dizziness and nausea; fatigue, sleepiness and sedation were also common. More than twice as many women taking flibanserin stopped taking it compared to placebo drop-outs.
The analysts also worry about what will happen if flibanserin is taken along with antidepressants and other drugs. "It is not clear if labeling alone will be sufficient to alert women to the numerous drug interactions that exist with flibanserin," they write.
Judy Norsigian of the Boston Women's Health Book Collective notes that women of childbearing age, or those who are breast-feeding, are advised to avoid drugs that affect brain serotonin, as flibanserin does.
Norsigian also points out that the diagnosis of hypoactive sexual desire disorder is controversial and may be eliminated or revised in the next update of the DSM-V, the bible of mental health disorders.
The FDA Advisory Committee on Reproductive Health Drugs doesn't have to take the staff's advice, and the FDA decision-makers don't have to follow the committee's recommendation.
Meanwhile, the PR drums are already beating. A website sponsored by Boehringer Ingelheim urges women to get a "sexual satisfaction checkup" and offers a helpful set of questions they can ask their partners about sex. (But first light some candles and get him in the right mood, the website counsels.)
The company also sponsored a four-part documentary on the Discovery Channel to educate women and doctors about HSDD. The TV show doesn't mention flibanserin – that would be illegal, since it hasn't been approved.
But Pharmalot blogger Ed Silverman notes that the Discovery treatment doesn't include any experts who have doubts about HSDD.
Update: The panel recommended 11-0 against FDA approval of the drug, saying the benefits don't outweigh the risks. For what it's worth, the panel comprised seven women and four men.