June 16 (Bloomberg) -- Boehringer Ingelheim GmbH’s sexual desire drug flibanserin may not be effective or safe, according to U.S. regulators weighing whether to approve the first pill designed to boost women’s libidos.
The drug “failed to demonstrate a statistically significant improvement” in sexual desire, Food and Drug Administration staff said in a review released today. It was also linked to appendicitis, depression and loss of consciousness. Side effects led about 15 percent of women to stop treatment with the drug, the review said.
While male sexual enhancement treatments led by Pfizer Inc.’s Viagra facilitate erections by increasing blood flow to the penis, flibanserin is designed to work in the brain. Boehringer’s libido pill, first tested as an antidepressant, lowers the level of one brain chemical, serotonin, and boosts production of two others, dopamine and norepinephrin.
“This points to the brain as the important organ in desire, as central to the feminine experience of sexuality,” said John Thorp, a professor of obstetrics and gynecology at the University of North Carolina School of Medicine and the lead investigator in North American drug trials sponsored by Ingelheim, Germany-based Boehringer. “This is a radical change.”
Boehringer, the world’s largest closely held drugmaker, asked the FDA to clear its pill to treat pre-menopausal women who suffer from hypoactive sexual desire disorder. Outside advisers to the FDA are scheduled to meet June 18 to review the drug.
Sex Drive
The condition, defined as a decrease in sex drive that causes problems in relationships, affects about 10 percent of women from the ages of 30 to 60, Thorp said. It is typically treated with therapy and with prescriptions of male hormones such as testosterone, an unapproved use, he said.
Taking male hormones can cause women to gain weight, grow facial hair, and face long-term health risks, Thorp said.
Noven Pharmaceuticals Inc.’s testosterone patch Intrinsa, licensed by Procter & Gamble Co., is sold in Europe for women whose uteruses have been removed. A U.S. version was put on hold in 2004 after an FDA advisory panel said the drug needed more study because existing research couldn’t rule out heart and breast cancer risks.
In clinical tests of 1,378 women in North America, 48 percent of patients who took flibanserin for six months reported improved desire, compared with 30 percent with a placebo, Boehringer reported at a May 18 meeting of the American College of Obstetricians and Gynecologists in San Francisco.
Female Libido
Female libido drugs may create an annual market of at least $2 billion, said Stephen Simes, chief executive officer of BioSante Pharmaceuticals Inc., in a June 9 presentation to investors. The Lincolnshire, Illinois-based company’s Libigel, a topical testosterone, is in the third and final stage of tests generally required for U.S. approval.
Viagra had sales of $1.89 billion last year, including $962 million in the U.S., Pfizer said Feb. 3. Cialis generated $1.56 billion in sales last year for Eli Lilly & Co., including $623.3 million in the U.S., the Indianapolis-based company reported Jan. 28.
“Viagra-like” drugs haven’t shown much success in women, said Jeffrey Jensen, a professor of obstetrics and gynecology at Oregon Health & Science University, in a telephone interview.
“That’s wrapped up in a whole bunch of stuff, not just plumbing,” Jensen said. “Treating male sexual arousal disorder is basically just plumbing -- getting blood flow to that area.”
I’m not sure if the flibanserin briefing docs are net bullish or net bearish for LibiGel. The absence of off-label competition from flibanserin is bullish, but the overall tenor of the briefing docs vis-à-vis the FSDD indication might be construed as bearish for LibiGel’s chances of gaining approval.
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