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FDA Okays First Treatment for Sexual Desire Disorder
The FDA has given the nod to flibanserin (Addyi, Sprout Pharmaceuticals) for the treatment of acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. Before this decision, there were no FDA-approved treatments for sexual desire disorders in men or women.
HSDD is characterized by low sexual desire that causes marked distress or interpersonal difficulty and is not due to a co-existing medical or psychiatric condition, problems within the relationship, or the effects of a medication or other drug substance. HSDD is acquired when it develops in a patient who previously had no problems with sexual desire. HSDD is generalized when it occurs regardless of the type of sexual activity, the situation, or the sexual partner.
Flibanserin is a serotonin 1A receptor agonist and a serotonin 2A receptor antagonist, but the mechanism by which the drug improves sexual desire and related distress is not known. Flibanserin is taken once daily. It is dosed at bedtime to help decrease the risk of adverse events occurring due to possible hypotension, syncope, and central nervous system depression, such as sleepiness and sedation. Patients should discontinue treatment after 8 weeks if they do not report an improvement in sexual desire and associated distress.
Originally developed by Boehringer Ingelheim, flibanserin was first rejected by the FDA in 2010 after an advisory panel said its benefits did not outweigh its risks. Sprout acquired the drug, conducted additional studies, and resubmitted the application. In 2013, the FDA rejected it again. This rejection sparked a lobbying campaign by Sprout, aided by some women’s groups who accused the FDA of gender bias because it had approved Viagra for men.
Flibanserin may cause severe hypotension and syncope, according to the FDA’s Center for Drug Evaluation and Research. These risks are increased and are more severe when patients drink alcohol or take flibanserin with moderate or strong cytochrome P450 (CYP) 3A4 inhibitors, which interfere with the breakdown of flibanserin in the body. Because of the alcohol interaction, the use of alcohol is contraindicated while taking flibanserin. Health care professionals must assess the likelihood of the patient reliably abstaining from alcohol before prescribing flibanserin.
The drug was approved with a risk evaluation and mitigation strategy (REMS), which includes elements to assure safe use (ETASU). The FDA is requiring an REMS because of the increased risk of severe hypotension and syncope due to the interaction between flibanserin and alcohol. The REMS requires that prescribers be certified with the REMS program by enrolling and completing training. Using a patient–provider agreement form, certified prescribers must counsel patients about the increased risk of severe hypotension and syncope and about the importance of not drinking alcohol during treatment with flibanserin.
Flibanserin was also approved with a boxed warning to highlight the risks of severe hypotension and syncope in patients who drink alcohol during treatment, in those who also use moderate or strong CYP3A4 inhibitors, and in those who have liver impairment. Flibanserin is contraindicated in these patients. In addition, the FDA is requiring Sprout Pharmaceuticals to conduct three well-designed studies in women to better understand the known serious risks of the interaction between flibanserin and alcohol.
The effectiveness of the 100-mg bedtime dose of Flibanserin was evaluated in three 24-week randomized, double-blind, placebo-controlled trials in approximately 2,400 premenopausal women with acquired, generalized HSDD. The trial participants’ average age was 36 years, and their average duration of HSDD was approximately 5 years. In these studies, women counted the number of satisfying sexual events, reported sexual desire over the preceding 4 weeks, and reported distress related to low sexual desire.
On average, treatment with flibanserin increased the number of satisfying sexual events by 0.5 to 1.0 additional event per month compared with placebo. Advocates claim that increase is meaningful. Critics say the small benefit is outweighed by the drug’s serious risks.
Public Citizen, a consumer watchdog group, has predicted that flibanserin will be pulled from the market within a few years because of “serious dangers to women, with little benefit” to them.
Sources: FDA; August 18, 2015; and Reuters; August 18, 2015.