A US drugmaker working to
develop a pill to boost sexual desire in women says regulators are demanding
more studies on the experimental drug.
Sprout Pharmaceuticals said that the Food and Drug Administration wants to see more data on how the
company's drug, flibanserin, interacts with other medications and how it
affects driving ability. Nearly 10 percent of women studied in company trials
reported sleepiness while taking the daily pill.
The FDA's request
represents another hurdle in the pharmaceutical industry's 15-year search for a
female equivalent to Viagra.
Request for additional studies
But in a news release,
Sprout Pharmaceuticals President Cindy Whitehead described the development as a
"significant step toward the approval of flibanserin". The three
studies requested by the FDA are relatively small, involving 25 to 50 patients
each. The company says it plans to resubmit its drug application to FDA during
The company said in
December that it had reached an "impasse" with regulators after the
agency issued a second rejection letter on the drug. The company filed a formal
dispute over the agency's decision, which prompted the FDA's latest request for
If approved, Sprout's daily
pill would be the first drug for women who report a lack of sexual desire, a
market that drug makers have been trying to tap since the blockbuster success
of Viagra for men in the late 1990s. While earlier drugs worked on hormone
levels, flibanserin is the first attempt to increase sexual desire by acting on
brain chemicals that affect appetite and mood.
The race to develop a
female libido booster was once dominated by multinational companies like
Viagra-maker Pfizer Inc. and Procter & Gamble, but today the space mainly
consists of tiny start-ups. Sprout Pharmaceuticals, led by a husband and wife
team, acquired flibanserin from Boehringer Ingelheim in 2011, after the German
conglomerate abandoned development following an FDA rejection letter.
Boehringer studies showed that women taking the drug reported only a modest
uptick in "sexually satisfying events".
The FDA's initial rejection
followed a 2010 meeting where a panel of expert advisers unanimously voted
against the drug, citing its lacklustre effectiveness and side effects such as
fatigue, dizziness and nausea.
Even if the FDA eventually
approves flibanserin, Sprout will have to convince doctors to prescribe the
drug for a condition that is still viewed with some scepticism.
Lack of sexual appetite
The drug would be
specifically approved for premenopausal women with hypoactive sexual desire
disorder, described as a lack of sexual appetite that causes emotional
Because so many factors
affect female sexual appetite, there are a number of other possible causes
doctors must rule out before diagnosing the condition, including relationship
problems, hormone disorders, depression and mood issues caused by other drugs
like sleeping aids and pain medications.
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