'Female Viagra' Is Rejected by FDA Panel

Advisory Committee Opposes Approval of Filbanserin to Treat Low Sexual Desire in Women

By Todd Zwillich
WebMD Health News

Reviewed By Laura J. Martin, MD

June 18, 2010 -- An FDA advisory panel unanimously rejected what some had hoped would become the first drug approved to boost sexual desire in women.

Experts said the drug, widely dubbed "female Viagra," showed little evidence of working and raised safety concerns. If the FDA follows the recommendation of the advisory panel, it would send drugmakers back to the lab in their quest to come up with a drug that could be marketed to women with lower-than-desired libidos.

German drugmaker Boehringer Ingelheim had hoped to sell the drug, known as flibanserin, as the first medication targeting low sexual desire in premenopausal women. They pointed to studies showing that women who took the drug reported slightly increased feelings of sexual desire and more satisfying sexual episodes than women who took a placebo.

But experts were unconvinced that the increases were clinically meaningful.

"This is not an effective drug," said Bryce Reeve, PhD, program director of the Outcomes Research Branch at the National Cancer Institute and a member of the advisory committee.

Experts were also troubled that the company abandoned part way through its study the scale it used to measure women's experience after less than promising results.

"This would be highly inappropriate," said Scott Emerson, MD, a professor of biostatistics at the University of Washington and a member of the advisory panel.

Flibanserin has been widely touted as the "female Viagra," though the moniker is not quite accurate. Unlike male erectile dysfunction drugs, which are taken minutes or hours before desired sexual activity, flibanserin is taken once a day. And while Viagra and similar drugs work directly on the physiology of the penis and do not increase actual sexual desire, flibanserin acts on the central nervous system, presumably in the pleasure centers of the brain.

Still, that has not stopped drugmakers from pursuing Viagra-like blockbuster status for a similar drug for women. In this case, Boehringer Ingelheim wanted to sell flibanserin to treat hyposexual desire disorder, or HSDD.

Debate Over Hyposexual Desire Disorder

Estimates suggest more than 6% of women between 30 and 39 years of age have HSDD. Numbers climb as women age and reach menopause.

But HSDD is itself at the center of a debate. Proponents call it a potentially devastating condition adversely affecting millions of women.

Boehringer Ingelheim officials invoked that debate as they made their case to experts Friday.

"Women suffering with HSDD deserve the option to choose a safe and effective pharmacotherapy for this distressing condition," said Anita Clayton, MD, a University of Virginia professor of psychiatry who testified on behalf of the company.

But others call HSDD little more than a condition conjured up by drug companies to push treatments, and note there is no scientifically accepted definition of normal sexual desire, much less reduced desire.

"Flibanserin is not a choice when it's promoted by bad science and half truths, said Leonore Tiefer, PhD, an associate professor of psychiatry from New York University who testified against the drug.

In addition to the questionable benefits of the drug, experts also said they were concerned about potential safety problems.

About one in seven women in two company studies dropped out because of adverse reactions including depression, dizziness, nausea, and fatigue.

Despite rejecting flibanserin, panelists did stress a belief that HSDD is a treatable clinical disorder in women.

"I hope [Boehringer Ingelheim] and others do look for a way to help women out," Reeve said.

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SOURCES: Bryce Reeve, PhD, program director, Outcomes Research Branch, National Cancer Institute; member, FDA advisory committee.

Scott Emerson, MD, professor of biostatistics, University of Washington; member, FDA advisory committee.

Anita Clayton, MD, University of Virginia professor of psychiatry, Boehringer Ingelheim consultant.

Leonore Tiefer, PhD, associate professor of psychiatry, New York University.

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