Nov. 19, 2009 -- An investigational drug that didn't perform well as an antidepressant appears to slightly boost sexual desire as well as the number of satisfying sexual encounters in women with lagging libidos, a study shows.
The research was presented this week at the 12th Congress of the European Society for Sexual Medicine in Lyon, France.
Some wonder if the drug, called flibanserin, will be the new ''female Viagra," but critics say the effect is minimal. Meanwhile, the manufacturer is planning additional clinical trials and expanding the participant pool to include older women.
The big news, according to those who studied flibanserin? "There is something that works on the neurotransmitters in the central nervous system to alter sexual desire in a positive way," says John M. Thorp Jr., MD, McAllister distinguished professor of obstetrics and gynecology at the University of North Carolina at Chapel Hill School of Medicine, and a principal investigator for the U.S. trials.
At the Congress, researchers reported the pooled results for 1,378 premenopausal women, average age 35, who took 100 milligrams of the drug or a placebo pill during a 24-week period. The trials were in Europe and North America. The women kept track of the number of satisfying sexual encounters -- defined as intercourse, oral sex, masturbation, or genital caressing by their partners. All women had to be in a stable, monogamous relationship. All women had a diagnosis of hypoactive sexual desire disorder (HSDD), marked by a decrease or absence of sexual desire accompanied by distress in the patient.
When researchers compared sexual desire and events during the last four weeks to the first four weeks, they found that those on the medication went from 2.8 sexually satisfying events in the first four weeks to 4.5 in the final four weeks. Those on placebo went from 2.7 to 3.7.
''The difference was [about] one additional satisfying sexual encounter a month," says Thorp.
The study also shows the drug improved sexual functioning and distress related to the sexual problems.
About 15% of the women taking the medication dropped out due to adverse events, according to information from Boehringer Ingelheim Pharmaceuticals, which makes the medications, while 7% of women on placebo discontinued the study. Among the most commonly reported side effects were daytime sleepiness, dizziness, anxiety, and fatigue.