The manufacturer of flibanserin, variously dubbed “female Viagra” or the “little pink pill” (in contrast to Viagra’s “little blue pill”), is continuing its fight to win federal approval to market a medication for the treatment of female sexual dysfunction.
At present, there is no drug on the market to treat the most common form of female sexual dysfunction, which is known as hypoactive sexual desire disorder, or HSDD.
Not at All Like Viagra
Calling flibanserin “female Viagra” is something of a misnomer because the two drugs work very differently from one another. Viagra and the other male impotence drugs promote strong blood flow to the penis. Flibanserin targets the brain, which many scientists believe is the primary sexual organ in females.
The battle to win FDA approval for flibanserin has been going on for several years. Boehringer Ingelheim Pharmaceuticals, the original developer of the drug, in the fall of 2010 withdrew its application for approval after negative feedback from an FDA advisory panel. The company also announced that it was discontinuing its development of the drug altogether.
Sprout Founded in 2011
Founded in 2011, North Carolina-based Sprout Pharmaceuticals is a spinoff from Slate Pharmaceuticals that was established with the express purpose of delivering a mode of treatment for female sexual dysfunction. Sprout acquired the rights to flibanserin from Boehringer Ingelheim and has been fighting to win FDA approval ever since.
At the heart of the ongoing battle is FDA’s demand for more extensive clinical testing of the drug before it can grant approval. For its part, Sprout has argued that it has already provided the federal agency with more than adequate proof of the drug’s efficacy and safety.
Rejections Decried
FDA’s rejections of Sprout’s new drug application, or NDA, for flibanserin, have been decried by some women’s groups, including the National Organization of Women.
Particularly outspoken was Anita H. Clayton, the interim chair of the department of psychiatry and neurobehavioral sciences at the University of Virginia. In an opinion piece written for the Huffington Post, Clayton said, “For the millions of women with HSDD, the FDA must overcome the problem of institutionalized sexism — unconscious and perhaps unintended, but damaging nevertheless.”
Women’s groups aren’t unanimous in their support of the fight to win FDA approval for flibanserin. In April 2014, the National Women’s Health Network led a campaign in support of the FDA’s “evidence-based evaluation” of the drug and “its continued strong stand that a drug cannot be approved when the minimal benefit does not outweigh the risks.”
Others Back NWHN Stand
Signing on to NWHN’s letter to Janet Woodcock, director of FDA’s Center for Drug Evaluation and Research, were the American Medical Women’s Association, Breast Cancer Action, Jacobs Institute for Women’s Health, New View Campaign, and Our Bodies Ourselves.
In February 2014, Sprout announced that it had received “clear guidance” from the FDA on the steps it should follow to resubmit its NDA, the most recent version of which was rejected in October 2013. Sprout said it hoped to complete the additional testing sought by FDA in time to resubmit its application by the third quarter of 2014.
What FDA Wants
Specifically, the FDA asked Sprout to complete two additional Phase I drug interaction studies and a Phase I driving simulator study. As Phase I studies, each is likely to include 25 to 50 healthy volunteers. The interaction studies will focus on potential adverse interactions on enzyme pathways other than those previously studied. The driving simulator study will explore whether use of the drug might result in any driving impairment. The FDA requested the driving study because nearly 10 percent of women in earlier studies reported sleepiness as a side effect of taking 100-milligram flibanserin.
Of the latest input from the FDA, Cindy Whitehead, Sprout’s president and chief operating officer, expressed optimism. “We are encouraged by the FDA’s response and view it as a significant step toward the approval of flibanserin. With data on over 11,000 patients to date, we are confident that further supporting the predictable risk/benefit profile of flibanserin will result in women having the first-ever treatment for the most common form of female sexual dysfunction.”
Mechanism of Action
As previously noted, flibanserin’s mechanism of action is completely different from the male impotence drugs currently on the market. Although the effects of the drug have been studied in both premenopausal and postmenopausal women, the current application to FDA seeks approval of the drug as a treatment of HSDD for premenopausal women.
More akin to an antidepressant in the way it works, flibanserin is said to target the neurotransmitters — brain chemicals — that control sexual desire in women. It is believed that the drug works by correcting an imbalance of these neurotransmitters by increasing dopamine and norepinephrine (both associated with sexual excitement) and lowering levels of serotonin (associated with sexual inhibition).
Risks Worry FDA
In its most recent rejection of the drug, the FDA expressed concern about flibanserin’s risks when counterbalanced with its “modest” efficacy as determined in one of the studies submitted in support of Sprout’s application. That study, published in 2013, was a randomized controlled trial involving a study group of more than 1,000 women and sponsored by Sprout.
In that study, women taking flibanserin reported an average monthly increase of 2.5 “satisfying sexual events,” compared with an average increase of 1.5 such events for women who got placebo.
HSDD Explored
In an article published in a 2002 issue of “CNS Drugs,” J.J. Warnock of the University of Oklahoma Health Sciences Center said that HSDD, the form of female sexual dysfunction targeted by flibanserin, may occur in up to one-third of adult women in the United States.
Its essential feature, according to Warnock, is an absence or deficiency of sexual fantasies and desire for sexual activity that can cause considerable interpersonal conflict as well as distress in the women suffering from the disorder. In some cases, the disorder can be traced to specific female reproductive life experiences, such as menstrual cycles, hormonal contraceptives, postpartum states, lactation, hysterectomy, and perimenopausal and postmenopausal states.
Quality of Life Affected
Warnock also wrote that HSDD is closely associated with low levels of physical and emotional satisfaction, as well as low levels of happiness, all of which can have an extremely negative impact on quality of life.
In sharp contrast to flibanserin, which targets chemical imbalances in the brain, men’s impotence medications, such as Viagra, promote strong blood flow to the penis, which is essential to achieve and maintain an erection strong enough for sexual activity.
Men’s prescription impotence drugs currently on the market belong to a family of medications known as PDE5 inhibitors, so-called because they temporarily block the effects of an enzyme known as phosphodiesterase-5. This enzyme can reduce the level of blood flow to the penis and thus prevent erection.
We specialize in providing our over 1,000,000 customers with relevant product and condition information created by our professional editorial staff which includes our team of medical writers, medical practitioners, and health educators. eDrugStore.com Staff on Facebook