It’s all but official. Hopes have been dashed, once again, for a “pink pill” that can boost low sex drive in females as quickly as the popular “blue pill” Viagra pumps up sex organs in males.
The German pharmaceutical company Boehringer Ingelheim recently released results from two large studies of pre-menopausal women who were treated for diminished sex drive with the drug flibanserin.
In a word, flibanserin flopped--at least in improving libido in most women tested. More studies are underway, but these recent results reconfirm that female sexuality is complicated and may not easily lend itself to a single pharmaceutical product.
Specifics on how the clinical trials were organized and what the results showed were made public this week in a large summary document from the Food and Drug Administration (FDA). See highlights of the study details and results below.
This information, plus the testimony from many experts in women’s health and female sexual dysfunction, will help a panel of analysts decide if flibanserin should be recommended for marketing to the public.
Details of the studies:
More than 1,200 pre-menopausal U.S. and Canadian women in long-term monogamous relationships received flibanserin in two double blind clinical experiments. A double blind study means neither the volunteer in the study nor the administrator knows which pill a volunteer receives—the real drug or a placebo pill-- until the end of the study. This keeps the volunteers and researchers from being swayed by their expectations for a positive or negative outcome while the study is underway. Four doses of flibanserin were tested in the treatment groups of women: 25 milligrams, twice per day; 50 milligrams, once per day; 50 milligrams, twice per day; and 100 milligrams, once per day.
The major goals of the two clinical trials were to examine safety and efficacy of flibanserin, standard objectives for what are called “phase III” clinical trials. Researchers looked at how well flibanserin improved the sexual activity and desire in the volunteers and also determined if any side effects occurred and how often. Women documented their sexual activity and level of desire every day for a month before the treatment started and daily for six months while they received treatment. Any health issues or potential side effects were also noted.
The participants averaged 35 to 37 years in age and included only women who had been diagnosed with hypoactive sexual desire disorder. The researchers define this condition as a “persistent absence of sexual fantasies and desire for sexual activity that is associated with personal distress.” The study participants were predominately highly educated Caucasian women in good health who did not take any of a large number of medications that were listed as prohibitory to enrolling in the trials. Reviewers of the two studies pointed out that this narrow selection of participants makes the results harder to interpret and potentially more difficult to apply to women in the more general population.
The results:
Women taking flibanserin once a day at the highest dose did report a slight increase in the number of monthly “satisfactory sexual events” during treatment compared to the placebo group. However, they did not report any change in their overall desire for sex while taking the drug. So in one way—level of sexual activity—the drug proved somewhat encouraging, but it missed the mark in the ultimate goal of boosting women’s libido in general.
The primary side effects associated with the drug included dizziness, nausea, fatigue, and drowsiness. Each of these side effects was reported in about 10-12 percent of participants taking flibanserin compared to three to six percent of the placebo group. Depression was also slightly higher in the groups of women taking the drug versus those given the placebo. Women using hormonal contraceptives, antidepressants (SSRIs), migraine medication (triptans) or alcohol, were more likely to have an adverse effect when taking flibanserin than if they were given the placebo treatment. The authors of the study also point out that 15 percent of the participants receiving flibanserin dropped out of the study due to some adverse side effect compared to less than seven to eight percent of participants given the placebo pill, indicating that the drug may be only moderately tolerated by the general population.
Over the next few weeks, experts will evaluate and debate this data to determine if the drug is effective and safe enough to be made available to women in the U.S. with low sexual drive. Stay tuned, but the outcome does not look too promising for flibanserin.
Source: “Background Document for Meeting of Advisory Committee for Reproductive Health Drugs (June 18, 2010).
http://www.fda.gov/downloads/AdvisoryCommittees/CommitteesMeetingMaterials/Drugs/ReproductiveHealthDrugsAdvisoryCommittee/UCM215437.pdf