Five Reasons Why Flibanserin is NOT Female Viagra!

  1. The evidence that flibanserin works is flimsy. Flibanserin is a drug that failed as an antidepressant and was repurposed as a cure for women who believe their desire for sex is too low. In a series of randomized double-blind clinical trials, women reported it to be slightly better than the placebo at increasing “pleasurable sexual events” and on several questionnaires measuring sexual desire and distress about sexual problems. Since we cannot measure sexual desire in any physiological way (like with a brain scan or a blood test), we depend on women’s reports of their experiences. Because the trials involved large samples of women, these slight differences were statistically significant–the traditional test of success for a clinical trial. In a double-blind trial, both researchers and subjects are supposed to have no idea who is taking the active drug vs. the placebo. However, the researchers failed to ask women if they could guess accurately whether they were taking the placebo or the real drug. In most trials of antidepressants, people can tell, based on drug side effects. Flibanserin can cause sudden drops in blood pressure leading to fainting, dizziness, sleepiness, nausea, and headache. If a woman thinks she is on the real drug, she may be biased to say it works. If she thinks she is on the placebo, she may be disappointed and say it did not work. These different beliefs taint a “double blind trial” and probably account for the small advantage of flibanserin over placebo.
  2. Flibanserin was approved because of pressure from publicity, not based on science. The Food and Drug Administration (FDA) turned down flibanserin twice, but approved it this time after the company that owns the drug paid to have selected women from their research trials travel to Washington, DC and testify, complete with tears, about how much they needed their flibanserin. They also mounted a large publicity campaign accusing the FDA of disapproving drugs for women’s sexual problems out of sexism. The FDA caved and approved a drug with little or no benefit and troubling side effects.
  3. Viagra does not improve men’s sexual desire. Viagra (and other medications in the same class) does not work in the brain. It works in the penis, by changing the chemistry within the soft, spongy tissue that fills with blood during an erection. It relaxes the tissue, allowing blood to flow in more easily. We do not have a drug that improves men’s sexual desire. Humans have searched for an aphrodisiac (something to improve desire) since ancient times. Most remedies were based on a vague resemblance to an erection, i.e. rhinoceros horn (a misconception responsible for the near-extinction of a species) or ginseng roots. If a man has a disease that stops his testicles from making testosterone, giving him more will return his desire to normal. It is unclear if the same effects hold in women, because we only need very tiny amounts of testosterone to have normal sex lives. Giving men or women extra testosterone may boost desire for a very short time, but then the high hormone levels shut down natural hormone production, resulting in long-term loss of desire. As one of my colleagues, an expert on male fertility, always says, “Why do you think male body builders fit into those tiny bikinis?” Furthermore, the hormone that acts in the brain to promote desire in women may actually be estradiol, a form of estrogen, and not testosterone at all!
  4. Studies of women with low desire do not suggest it has a biological cause. One issue is: what is a normal level of desire for sex? In Victorian times, women were expected not to feel any desire, but to spread their legs and think of England. Now we expect women to want sex all the time. Women judge themselves against these unrealistic standards, so that in some studies, 40% of American women say they have “low desire.”  Actual research on women’s interest in sex identifies the following top reasons women lose desire: conflict in a relationship, depression, and high life stress. Fix those with a pill! I work with women who have had cancer treatment. Many notice a troubling loss of desire and want a pill to feel better. Unfortunately, their problems are often linked to developing vaginal dryness that makes sex painful; being on multiple drugs for depression, sleep, nausea, and pain; long-term fatigue in the months after treatment; and fears that a partner will no longer find them sexy and attractive.
  5. There is another new drug with a much better claim to being a “female Viagra,” but its sales have been a big disappointment (as have initial sales of flibanserin, marketed as Addyi®). It is called Osphena® (ospemifene) and is a manmade hormone (selective estrogen receptor modifier or SERM) that reverses changes in the vulva and vagina after menopause that cause severe vaginal dryness and pain during sex. Sixty percent of postmenopausal women have pain when they have sex–a far more major problem than loss of desire. Vaginal changes after menopause are also parallel in many ways to the increase in erection problems in aging men. Studies of ospemifene in animals and humans suggest it is probably effective in preventing osteoporosis, and may even prevent breast cancer, two other blockbuster problems in aging women. Yet the FDA put a “black box” warning on the drug packaging saying that women with a history of breast cancer or cancer of the uterus should not take it. I wrote the company that owns the patent for ospemifene to see if they plan research on the drug’s helpfulness for osteoporosis or breast cancer prevention, and they answered curtly that they did not. A similar, and even better drug, lasofoxifene, was not approved initially by the FDA, but now may be brought back to market if further trials can demonstrate its safety. These drugs have the potential to truly change the sex lives of aging women, as well as helping with bone density and breast cancer, but they have received little or no notice in the public press.

I am deeply disappointed and disturbed that the FDA has acted like the lackey of pharma marketers instead of a regulatory body. As a psychologist who has devoted my career to trying to prevent or improve sexual problems in men and women, I believe in treatments that combine medical and psychological options. My fear is that this approval will embolden renewed appeals for two drugs the FDA previously rejected, both forms of the hormone testosterone. Research trials on those drugs have the same flaws as the studies of flibanserin. However, giving women extra testosterone may have the potential to speed the growth of  breast cancer. We know that testosterone feeds some breast tumors. All we need is approval of another drug that is next to useless, and could actually kill women.

This educational material is intended for informational purposes only and is not intended to replace, or substitute for, professional advice, counseling, diagnosis, or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a condition. Never disregard professional advice or delay in seeking treatment because of something you have read in this educational material.

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