Sprout Pharmaceuticals is heading back to the FDA with a twice-rejected treatment for female sexual dysfunction, betting that its follow-on studies will be enough to finally convince the agency.
The drug, flibanserin, is a pill designed to help premenopausal women diagnosed with hypoactive sexual desire disorder (HSDD) regain their sex drives by boosting dopamine and norepinephrine levels in the brain. In the drug's past run-ins with the FDA, agency staff took issue with its "modest" efficacy and its potential for dangerous drowsiness if taken daily. In its last rejection, the FDA asked Sprout to conduct two Phase I drug-interaction studies and run a third trial to determine whether the treatment impairs patients' driving ability.
Now the company has done all that, returning to the agency with a package of data it believes will make flibanserin the first approved treatment for HSDD.
Flibanserin, previously abandoned by Boehringer Ingelheim, failed to impress regulators in its first submission in 2013, and the agency denied Sprout's ensuing appeal. In its pivotal trials, the drug led to statistically significant improvements in increasing sexual desire, decreasing distress and improving the number of self-reported "satisfying" encounters per month, according to Sprout. FDA reviewers were unmoved by the pill's efficacy, but "flibanserin does not cause hypersexuality," CEO Cindy Whitehead said last year, and "by that definition, 'modest' would be what we're aiming for."
Meanwhile, the FDA is under mounting pressure from advocacy groups who point out that the agency has approved 24 treatments for male sexual dysfunction and not one for women. That disparity is a reflection of how male sexual health is valued higher than female sexual health, some say, and "that's the cultural attitude that I want to be sure the FDA has not, maybe unconsciously, imported into its deliberative process," Terry O'Neill, president of the National Organization for Women, told NPR.
For its part, the agency says its reticence to approve flibanserin (or any other female libido drug) can be explained simply: None of them works very well. Furthermore, the differences involved in assessing male and female libido drugs don't make the FDA's task any easier. Erectile dysfunction is, at its core, a physiological problem, making the definition of clinical endpoints fairly straightforward. What drugs like flibanserin intend to treat--desire--has a much larger psychological component, meaning the FDA must consider subjective endpoints like "satisfying sexual encounters" in its deliberations, which makes for a more nebulous process.
"The FDA has devoted significant resources to understand HSDD and the need for medical treatment," Whitehead said in a statement. "I believe that the agency's efforts to bring together panels of patients and clinical experts will prove to be a significant step in bringing about a solution for women with HSDD to market. This year, I am optimistic that women and their partners affected by the life impact of HSDD will have their first potential medical solution."
- read the announcement
- here's the NPR story