The first drug to treat sexual dysfunction in premenopausal women – dubbed the “female Viagra” – has received approval from the US Food and Drug Administration.

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Flibanserin has been approved by the FDA to treat premenopausal women with low sexual desire.
Image credit: G. Breed/Associated Press

Manufactured by Sprout Pharmaceuticals, flibanserin (brand name Addyi) has been given the green light by the federal drug agency for the treatment of hypoactive sexual desire disorder (HSDD) – a condition characterized by low sexual desire.

It is estimated that around 1 in 10 women develop HSDD, and up to 40% experience the condition at some point in their lives. Psychological factors, such as low self-esteem, stress or mental health problems may contribute to low sexual desire, as well as hormone changes or physical factors, such as fatigue or lifestyle habits.

While the exact mechanisms by which flibanserin works is unclear, Sprout Pharmaceuticals believe it corrects an imbalance in brain chemicals that are responsible for sexual desire.

The US Food and Drug Administration (FDA) say a 100-mg dose of the drug should be taken once daily just before bedtime. Patients should discontinue use if they experience no improvement in sexual desire within 8 weeks.

“Today’s approval provides women distressed by their low sexual desire with an approved treatment option,” says Dr. Janet Woodcock, director of the Center for Drug Evaluation and Research (CDER) at the FDA.

“The FDA strives to protect and advance the health of women,” she continues, “and we are committed to supporting the development of safe and effective treatments for female sexual dysfunction.”

The FDA reached their decision by conducting an analysis of three randomized, double-blind, placebo-controlled trials involving around 2,400 women of an average age of 36 years who had HSDD.

For a 24-week period, the women took either a placebo or a 100-mg dose of flibanserin before bedtime. The women who took flibanserin reported a modest increase in sexual desire and the number of sexual events during the study period, as well as a reduction in distress as a result of low sexual desire.

On assessing the safety of the drug, the FDA report the most common adverse reactions identified were nausea, dizziness, fatigue, sleepiness, insomnia and dry mouth.

However, the organization notes flibanserin is also associated with hypotension – severely low blood pressure – and loss of consciousness, particularly if taken with alcohol. Such side effects have led the FDA to reject the drug twice previously – once in 2010 and again in 2014.

As such, their approval of flibanserin comes with a risk evaluation and mitigation strategy (REMS), which requires that all prescribers enroll in and complete a training program before treating patients with the drug.

“Because of a potentially serious interaction with alcohol, treatment with Addyi will only be available through certified health care professionals and certified pharmacies,” says Dr. Woodcock. “Patients and prescribers should fully understand the risks associated with the use of Addyi before considering treatment.”

In addition, a Boxed Warning is being applied to flibanserin, informing patients about the risk of hypotension and concussion if taken with alcohol, as well as warning patients with liver impairment or those taking moderate or strong CYP3A4 inhibitors to avoid use of the drug.

The FDA also require that Sprout Pharmaceuticals carry out three well-designed studies in order to further assess the health risks associated with flibanserin on interaction with alcohol.

While many women and health care professionals may welcome the FDA’s decision to approve flibanserin, others are likely to have concerns.

Back in June, a Spotlight from Medical News Today investigated whether flibanserin will really help women with low sexual desire.

Thea Cacchioni, an assistant professor of women’s studies at the University of Victoria in British Columbia, told us she was not convinced the current evidence of flibanserin’s safety and efficacy would be enough to gain FDA approval.

“I have faith that the FDA will stand its ground and not approve flibanserin,” she said. “If they do, they are sending a very dangerous message – that drug companies and their marketing machines can pressure them into approving drugs that are unsafe and ineffective.”

While the FDA’s approval of flibanserin comes with conditions reflecting their safety concerns, the decision has still been met with criticism, with one health expert hailing it a “sad day for drug regulation.”

“What has been learned since the last disapproval is that it has more risks than we thought and it doesn’t have any more benefits. The only thing that’s different is a clever, aggressive public relations campaign that Sprout Pharmaceuticals waged successfully,” Adriane Fugh-Berman, a pharmacology professor at Georgetown University in Washington, DC, told The Washington Post.

“This opens the way for drug companies to pressure the FDA through public relations campaigns to approve more bad drugs: It’s bad news for rational drug approval,” she adds.

Despite this criticism, Cindy Whitehead, CEO of Sprout Pharmaceuticals, believes the FDA’s decision to approve flibanserin is the right one:

It has been a remarkable journey to get to this breakthrough moment. Today we celebrate what this approval means for all women who have long awaited a medical treatment option for this life-impacting condition.

We applaud the FDA for putting the patient voice at the center of the conversation and for focusing on scientific evidence.”

Flibanserin will be available from mid-October, according to Sprout Pharmaceuticals, and is expected to cost between $30 and $75 a month for women with medical insurance.