The approval specified that flibanserin should not be used to treat low sexual desire caused by co-existing psychiatric or medical problems; low sexual desire caused by problems in the relationship; or low sexual desire due to medication side effects.As of 21 August 2015, The Pharmaceutical Journal reported that Sprout Pharmaceuticals had not yet made an application to the European Medicines Agency for a marketing authorisation. Advocacy groups
Even the Score, a coalition of womens groups brought together by a Sprout consultant, actively campaigned for the approval of flibanserin. The campaign emphasized that several approved treatments for male sexual dysfunction exist, while no such treatment for women was available. The group successfully obtained letters of support from the President of the National Organization for Women, the editor of the Journal of Sexual Medicine, and several members of Congress.Other organizations supporting the approval of flibanserin included the National Council of Womens Organizations, the Black Womens Health Imperative, the Association of Reproductive Health Professionals, National Consumers League, and the American Sexual Health Association.The approval was opposed by the National Womens Health Network, the National Center for Health Research and Our Bodies Ourselves. A representative of PharmedOut said "To approve this drug will set the worst kind of precedent — that companies that spend enough money can force the FDA to approve useless or dangerous drugs."
Mechanism of action
Activity profile
Flibanserin acts as a full agonist in the frontal cortex and the raphe dorsalis, but only as a partial agonist in the CA3 region of the hippocampus of the 5-HT1A receptor (serotonin receptor) (Ki = 1 nM in CHO cells, but only 15–50 nM in cortex, hippocampus and dorsal raphe) and, with lower affinity, as an antagonist of the 5-HT2A receptor (Ki = 49 nM) and antagonist or very weak partial agonist of the D4 receptor (Ki = 4–24 nM). Despite the much greater affinity of flibanserin for the 5-HT1A receptor, and for reasons that are unknown (although it might be caused by the competition with endogenous serotonin), flibanserin occupies the 5-HT1A and 5-HT2A receptors in vivo with similar percentages. Flibanserin also has low affinity for the 5-HT2B receptor (Ki = 89.3 nM) and the 5-HT2C receptor (Ki = 88.3 nM), both of which it behaves as an antagonist of. Flibanserin preferentially activates 5-HT1A receptors in the prefrontal cortex, demonstrating regional selectivity, and has been found to increase dopamine and norepinephrine levels and decrease serotonin levels in the rat prefrontal cortex, actions that were determined to be mediated by activation of the 5-HT1A receptor. As such, flibanserin has been described as a norepinephrine–dopamine disinhibitor (NDDI).The proposed mechanism of action refers to the Kinsey dual control model of sexual response. Various neurotransmitters, sex steroids, and other hormones have important excitatory or inhibitory effects on the sexual response. Among neurotransmitters, excitatory activity is driven by dopamine and norepinephrine, while inhibitory activity is driven by serotonin.