Female Sexual Desire Drug Rejected by U.S. Regulators

A pill to treat low sexual desire in women was rejected by U.S. regulators, a decision that has been appealed by the drug’s maker in a bid to make it the first product for the disorder.

The U.S. Food and Drug Administration based its decision to turn down the medicine on what the agency called a modest effect, closely held Sprout Pharmaceuticals Inc. said today in a statement. Sprout, based in Raleigh, North Carolina, is seeking approval of the therapy, known as flibanserin, as an option for women whose low libido causes stress in their lives.

In clinical trials, Sprout’s pill almost doubled the increase women saw in satisfying sexual experiences over a month’s time compared with patients who took a placebo, the company said. The agency’s decision contrasts with its review of drugs to treat male sexual dysfunction, Cindy Whitehead, president and chief operating officer at Sprout, said in an interview. The agency on Dec. 6 issued its 24th approval of a treatment for male sexual dysfunction, an injection called Xiaflex to treat a condition that causes a curved penis.

“I do believe that women deserve a solution to their most common form of sexual dysfunction,” Whitehead said. “Flibanserin has been in 11,000 patients at this point. It’s pretty well defined.”

The FDA accepted Sprout’s appeal on Dec. 3 after turning down the drug about two months ago. Because Sprout isn’t publicly traded, the company didn’t make public when the pill was rejected.

Causes Stress

Flibanserin, if approved, would treat a sexual disorder known as female hypoactive sexual desire disorder, which is low libido that causes stress, according to Sprout. The drug is indicated for use by women who haven’t yet gone through menopause.

“I think this could be a blockbuster drug,” Whitehead said.

Sprout expects to hear FDA’s decision on its appeal in the first quarter of next year.

Treatments for female sexual dysfunction have lagged behind those for men in the 15 years since Pfizer Inc.’s Viagra was approved for erectile dysfunction. Treatment for men has since grown into a $4.4 billion market in 2012, according to data compiled by Bloomberg.

Pfizer gave up studying Viagra for women in 2004. BioSante Pharmaceuticals Inc.’s testosterone gel for women failed to work in two large studies in 2011.

“Women’s sexual health has been really underground,” Sheryl Kingsberg, chief of the Division of Behavioral Medicine at Case Medical Center in Cleveland, said in an interview. “One reason that women’s sexual desire has lagged is desire is in the brain.”

FDA Effort

The FDA identified female sexual dysfunction as one of the conditions the agency has selected as part of an effort to stress the perspective of patients in drug development. The agency plans to hold a meeting with patients in 2014 or 2015, according to the FDA’s website.

Flibanserin is a non-hormonal treatment that, similarly to antidepressants, lowers the level of the chemical serotonin in the brain and boosts dopamine and norepinephrine. Sprout gave the FDA data on 11,000 women in clinical trials, 3,000 of whom were part of new trials. Women in the studies were asked to count the number of satisfying sexual encounters they experienced.

The mean number of satisfying sexual events women on flibanserin recorded in a daily diary increased by 2.5 compared with 1.5 for those who received a placebo over a 28-day period, according to a study published in the Journal of Sexual Medicine in May.

Fatigue, Sleepiness

Side effects associated with flibanserin include fatigue, nausea and sleepiness.

“I think the patient can assess the benefit to them and talk to their doctor about it,” Whitehead said.

Very few appeals the FDA accepts are granted, including none in 2011 and only three of 17 last year, according to a presentation earlier this year by Amy Bertha in agency’s Office of New Drugs. Regardless, Whitehead said Sprout wants to gain clarity about what is necessary to move forward.

Sprout acquired the rights for flibanserin for an undisclosed amount from Boehringer Ingelheim GmbH in 2011 after the FDA told the Ingelheim, Germany-based drugmaker in October 2010 that the treatment hadn’t been proven safe or effective. Sprout said it conducted new tests altering how women’s sexual desire was measured.

Palatin Technologies Inc., based in Cranbury, New Jersey, is studying the drug bremelanotide for female sexual dysfunction.

About 43 percent of women experience some sort of sexual dysfunction and one in 10 women have low desire with accompanying distress.

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