The Food and Drug Administration (FDA) Advisory Committee voted 18-6 today in favor of approving flibanserin, an investigational agent for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women if certain risk management options beyond labeling are implemented.. This is the third time the drug faced the advisory committee panel for review of efficacy and safety issues.

Flibanserin is an investigational, once-daily, non-hormonal drug, and if approved, would be the first and only post-synaptic 5HT1A receptor agonist and 5HT2A receptor antagonist available for the treatment of premenopausal women with HSDD. Flibanserin may work by restoring prefrontal cortex control over the brain’s motivation/rewards structures enabling sexual desire to manifest. Specifically, flibanserin increases dopamine and norepinephrine while transiently decreasing serotonin in the brain’s prefrontal cortex, which may be accomplished by reduced glutamate transmission.

In February 2015, Sprout Pharmaceuticals announced that it had resubmitted its New Drug Application (NDA) to the FDA which included additional studies that the agency requested in its Complete Response Letter back in 2013. Previously, flibanserin was evaluated in three pivotal Phase 3, randomized, double-blind, placebo-controlled, parallel-group North American studies of premenopausal women with a mean age of 36 years. In all trials, flibanserin demonstrated a statistically significant difference compared to placebo on three key endpoints: an increase of sexual desire; a decrease in distress from the loss of sexual desire; and an increase in the frequency of satisfying sex.

Should the FDA Advisory Committee recommend that this drug be approved?

In this third review, the advisory panel considered all efficacy and safety issues, specifically whether the observed placebo-corrected treatment effects outweigh the risks associated with treatment and the serious risks of hypotension and syncope. Hypotension and syncope can occur with flibanserin alone and the risk is amplified by drug interaction and with concomitant alcohol intake. The most significant drug interactions occur with moderate and strong CYP3A4 inhibitors. While screening for drug interactions can help manage risk, the agency believes that the interaction between flibanserin and alcohol is more challenging to mitigate, particularly because flibanserin requires chronic administraion and alcohol use is pervasive in society. In the alcohol interaction study, the combination of ethanol and flibanserin precipitated concerning cases of hypotension and pre-syncope/syncope.

There has been extensive publicity surrounding flibanserin and female sexual dysfunction with some alleging that there is gender bias at the FDA given the number of treatments already approved for male sexual dysfunction. The Advisory Committee recommendation is non-binding and will be considered by the FDA.

“We are pleased with the positive outcome of today’s Advisory Committee meeting and the confidence that was expressed regarding the efficacy and safety of flibanserin,” said Cindy Whitehead, chief executive officer of Sprout Pharmaceuticals. “With today’s decision, we are one step closer to bringing to market the first treatment option for the most common form of female sexual dysfunction. We look forward to continuing our work with the FDA as it completes its review of our new drug application, including the discussion of a Risks Evaluation and Mitigation Strategy (REMS).” If approved, Sprout Pharmaceutics plans to market flibanserin under the name Addyi. 

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