Petite Pink Pill Promotes Female Libido

Sex Pill Flibanserin Is Mired in Drama

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To its detractors, flibanserin, a pink pill targeting female libido and made by Sprout Pharmaceuticals, is just another example of disease mongering. Disease mongering refers to the practice of pharmaceutical companies and others "pathologizing" aspects of the human condition in order to make a buck. For example, halitosis or bad breath only became a condition that needed treatment after Listerine was developed to "treat" it.

However, to its supporters, female sexual interest/arousal disorder is a very real disease, and flibanserin can help. These supporters cite the distress caused by a diminished or nonexistent sex drive.

What Is Female Sexual Interest/Arousal Disorder?   

Female sexual interest/arousal disorder refers to a reduction or absence of sexual interest in a woman that lasts 6 or more months and causes distress or interpersonal difficulties. Moreover, such disinterest is unattributable to another disease (think diabetes or depression) or drug (think antidepressants). It's important that this loss of sexual desire causes distress or difficulty because, otherwise, it's not really a problem. After all, lots of people have a long-standing disinterest in sex that doesn't cause personal problems, and this is fine.

Researchers posit that female sexual interest/arousal disorder involves complex brain circuitry controlling reward processing.

Specifically, this condition affects frontostriatal pathways and neuronal projections of the insula, amygdala, hypothalamus and ventral striatum. In women with such sexual interest and arousal issues, sexual motivation and pleasure are adversely affected. Of note, aberrant reward processing slices into other psychiatric disorders including depression, schizophrenia, substance abuse, dementia, eating disorders and other sexual disorders.

Interestingly, researchers have discovered changes on functional MRI that suggest macrocircuit anomalies attributable to female sexual interest/arousal disorders. For instance, women diagnosed with this disorder exhibit abnormal activation in the brain's cortical and striatal regions.

How Does Flibanserin Work?

It's really difficult (impossible) for scientists to measure specific neurotransmitter levels in different parts of the brain. However, using microdialysis techniques and nodes within brain networks, researchers postulate that flibanserin increases the release of both dopamine and norepinephrine and reduces the release of serotonin in women with reduced sexual interest and desire. More specifically, flibanserin can distinguish between serotonin receptors and stimulate serotonin 5HT1A receptors while blocking serotonin 5HT2A receptors in the prefontal cortex thus increasing the downstream release of dopamine and norepinephrine. Apparently, these combined neurotransmitter effects help better regulate reward processing and increase feminine libido.

Of particular note, flibanserin works on neurotransmitters, not hormones. Although hormones have proven effective in boosting libido, adverse effects make them too risky as treatment. Moreover, flibanserin is not "female Viagra." Viagra works by increasing blood flow to the genitals using a completely different mechanism and affecting a different site of action (genitals vs. brain).

Results from tw clinical trials titled BEGONIA and DAISY (ah, names of flowers ... how cute!) suggest that flibanserin can increase feminine libido. Combined, these randomized and placebo-controlled trials examined 3548 women with sexual interest and arousal disorder. After 24 weeks of once-daily treatment with 100 mg flibanserin, satisfying sexual events, sexual desire and distress caused by low sexual desire were measured using various (subjective) questionnaires. Researchers observed that in participants taking flibanserin--as compared with those taking placebo--there was an increase in number of satisfying sexual encounters and level of sexual desire and a decrease in distress caused by low sexual desire.

Serious adverse events in these trials occurred in fewer than one percent of participants, and none of these serious events were attributable to flibanserin treatment itself. Less serious adverse effects included dizziness, nausea, fatigue and sleepiness (most common).

Another randomized- and placebo-controlled trial named SNOWDROP (I'm seeing a pattern, here ... another flower name!), examined 949 postmenopausal women with female sexual interest/arousal disorder (technically hypoactive sexual desire disorder--a DSM-IV-TR term that has since been modified to sexual interest/arousal disorder in DSM-5). Much like the other trials, results indicate that fibanserin improves sexual desire, number of satisfying sexual events and reduces sexual distress all while causing few adverse effects. Specifically, 37.6 percent of women on flibanserin versus 28.0 percent of women taking placebo reported satisfying sexual events.

Although in some of these studies researchers attempted to include participants taking antidepressant medications, antihypertensives, triptans and some antifungals, one major limitation of these studies is sampling bias. In other words, because issues with sexual arousal and desire are pervasive and affect all types of women, it was hard to test whether flibanserin works in everyone.

Citing concerns about safety and efficacy, the FDA has refused to approve flibanserin twice--rejections with which its maker, Sprout Pharmaceuticals, and others take issue. From a medical treatments perspective, I definitely sympathize with the FDA's concerns. After all, flibanserin tools with several neurotransmitters and considering that many of the women who will take the drug will also be taking other drugs that further alter neurotransmitter levels -- like antidepressants and anxiolytics -- it's best to take a cautionary stance.

Conclusion

Many people honestly don't know what to think of flibanserin. On the one hand, many people are suspect of pharmaceutical companies and their intentions and predict that if approved, flibanserin may be overprescribed to certain women like those who experience no distress related to a paucity of sexual desire or arousal. On a related note, everything about Sprout's marketing of flibanserin screams manipulation including the pill's pink color and floral-monikered clinical trials. On the other hand, it's hard to understand the effects of flibanserin unless you're a woman who uses the drug.

Selected Sources

Article titled "Efficacy and safety of flibanserin in postmenopausal women with hypoactive sexual desire disorder: results of the SNOWDROP trial" by JA Simon and co-authors published in Menopause: The Journal of The North American Menopause Society published in 2013.  Accessed on 2/17/2015.

Article titled "Mechanism of action of flibanserin, a multifunctional serotonin agonist and antagonist (MSAA), in hypoactive sexual desire disorder" by SM Stahl published in CNS Spectrums in 2015.  Accessed on 2/17/2015.

Article titled "Improving prospects for treating hypoactive sexual desire disorder (HSDD): development status of flibanserin" by J Thorp, Jr, and co-authors from BJOG published in 2014.  Accessed on 2/17/2015.

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