Flibanserin

What is Flibanserin?

Flibanserin is a medication originally developed to treat depression. During clinical trials it was discovered that Flibanserin was useless as an antidepressant but it increased libido in women with low levels of sexual desire.

How effective is Flibanserin?

During clinical trials involving 5,000 women aged over 18, positive results were reported by the patent holder, Boehringer Ingelheim. There have been three separate trials lasting 24 weeks. All of the women participating had been diagnosed with hypoactive sexual desire disorder. They were spilt into two groups, one where the participants were given a placebo and one where the participants were given a daily 100mg dose of the drug.

In the latest trial, those taking the drug reported more satisfying sexual events than those given the placebo. Before the trial, there was an average of 2.8 satisfying sexual encounters per month as the average for the group, whereas afterwards those taking the drug saw this rise to 4.5 events per month, compared to 3.7 for those on the placebo.

Hypoactive Sexual Desire Disorder

Scientists estimate that this condition affects somewhere between 9% and 26% of the female population, though this depends on age and whether women have been through the menopause. There is some controversy surrounding potential drug treatment for this condition as some sex researchers believe drug treatment will not deal with psychological reasons for low libido, such as low self-esteem or stress. One treatment has already been approved for post-menopausal women, Intrinsa. Intrinsa is hormone based and is not appropriate for a lot of women who suffer from Hypoactive Sexual Desire Disorder.

How does Flibanserin work?

The researchers do not yet know exactly why this medication did not work as an anti-depressant but did increase libido. Flibanserin is an agonist of one of the serotonin receptors (5 - HT1A) and an antagonist at receptor 5 - HT2A. It is not known exactly how Flibanserin produces the sexual desire response but it is believed to involve a rebalancing of certain neurotransmitters in the brain related to inhibitory and excitatory responses, thereby producing a "normalization" of sexual desire.

One particularly interesting aspect of Flibanserin is that it increases sexual desire without affecting mood.

Flibanserin side effects

As with all medications, Flibanserin is not without side effects although they appeared to be rather minor. Side effects during the first two weeks of the trials included dizziness, fatigue, anxiety, nausea, dry mouth and insomnia. 15% of participants dropped out of the trial due to the side effects but the majority of those who reported them said that they resolved themselves when the treatment was continued beyond the first two weeks long period.

The researchers do not have data on any long-term side effects beyond 6 months.

When will Flibanserin be available?

The clinical trials of Flibanserin have not yet been completed and the drug has not been approved by either the F.D.A. or the European Medicines Agency. The manufacturers say that they hope it could be available in 18 months. Studies are currently taking place into how Flibanserin works when combined with other medications, such as anti-depressants.