Sprout Pharmaceuticals’ drug to treat low sexual desire in women secured regulatory approval late Tuesday, but the FDA’s nod comes with a strict monitoring program to guard against safety risks associated with the drug.
The FDA notes that flibanserin (Addyi) can cause severe low blood pressure, as well as the loss of consciousness—risks that are exacerbated with alcohol or certain drugs that interfere with the way that flibanserin is broken down in the body. For those reasons, the FDA is requiring that patients seeking flibanserin to treat hypoactive sexual desire disorder—essentially low libido— get a prescription from certified physicians who must counsel patients on the drug’s risks. Prescriptions can only be filled by pharmacies certified to dispense the Raleigh, NC-based company’s drug, and those pharmacies must receive training on the drug’s risks.
Flibanserin will also carry a boxed warning highlighting the drug’s risks and the FDA is requiring Sprout to conduct three post-marketing studies in women “to better understand the known serious risks of the interaction between Addyi and alcohol.” The most common adverse reactions associated with the use of flibanserin are dizziness, sleepiness, nausea, fatigue, insomnia and dry mouth.
The FDA says that Sprout’s drug is the first approved treatment for sexual desire in either men or women but the drug’s approval was far from certain after it previously failed three times before the FDA. Flibanserin was originally developed by German company Boehringer Ingelheim, which initially studied the drug as a depression treatment. According to FDA documents, flibanserin’s mechanism of action is not known, though clinical testing of the drug showed that the drug affects receptors in the brain associated with mood.
While mid-stage clinical trials of flibanserin failed to show efficacy in treating depression, Boehringer Ingelheim noted that patients in the studies noted improvement in their sex drive. The German company changed gears and pursued FDA approval for the drug as a treatment for hypoactive sexual desire disorder in 2010. The FDA rejected the application due to questions about the drug’s efficacy and safety. Sprout acquired Boehringer Ingelheim’s rights to flibanserin in 2012, and prepared to resubmit the drug to the FDA for approval using the German company’s clinical trial data. But in 2013, Sprout twice failed to overcome FDA concerns that the drug’s risks outweigh its benefits. The FDA requested additional studies, and also said that concerns about the drug warranted a review by an independent panel of medical experts.
Flibanserin was evaluated in three blinded, placebo-controlled trials in 2,400 premenopausal women with hypoactive sexual desire disorder. Efficacy of Sprout’s 100 mg pill was measured by having trial participants count the number of satisfying sexual events they experienced during the study. According to trial results, women treated with the Sprout drug reported between 0.5 to 1 additional sexually satisfying event per month, compared against patients who received a placebo. The clinical trials also evaluated patient reports that the drug improved how they felt. In the three trials, 10 percent more patients treated with the Sprout drug reported “meaningful improvements in satisfying sexual events, desire or distress.” In June, the independent advisory panel voted 18-6 to recommend approval for flibanserin, as long as the drug would also be subject to programs monitoring its safety.
Sprout said in a written statement that it is committed to the post-marketing studies of its drug required by the FDA. The company expects to make flibanserin available by Oct. 17.
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