What would Frances Kelsey have made of the new libido pill for women, Addyi (generic name: flibanserin), recently approved by the US Food and Drug Administration (FDA)? Kelsey, who died last month aged 101, became one of the most respected women in US medicine for her role at the FDA in keeping the drug thalidomide off the American market1. Thanks largely to her, Congress passed the 1962 Kefauver-Harris Drug Amendment, requiring that all manufacturers provide “substantial evidence” of a drug’s safety prior to FDA approval. Kelsey was a scientist who followed the evidence, so she is unlikely to have been convinced by the lobbying campaign that argued that, despite Addyi’s modest performance in trials and worrying potential side effects, it should be approved because, while many treatments exist for male sexual dysfunction, no such treatment is currently available for women.
Addyi may help some women who experience low desire. But claims that it will be the “female Viagra” are premature hype. For a start, Viagra and Addyi are very different. Flibanserin, to give Addyi its generic chemical name, is an anti-depressant similar to the SSRI (selective serotonin reuptake inhibitor) group that includes Prozac. It operates on neurotransmitters, chemicals released by nerve cells in the brain to send signals to other nerve cells. It is believed that what excites us is driven largely by the neurotransmitter dopamine (addictive drugs for example flood our brains with dopamine), while what brings us down is driven by serotonin, the neurotransmitter thought to be an active agent in depression. The balance between these chemicals in the brain seems to modulate normal sexual response. By increasing the former and reducing the latter, flibanserin should regulate how horny someone feels.
However, neuroscience still has a sketchy understanding of how this brain chemistry works, and flibanserin failed to have much effect when it was first tested as an anti-depressant and was turned down by the FDA. In contrast, Viagra-like drugs for men increase blood flow to the penis to establish and maintain an erection. They act through the better understood mechanics of the cardiovascular system (Viagra itself was a originally a heart disease treatment).
How effective flibanserin will be in helping women with low desire has also been questioned. One clinical trial found that women treated with Addyi experienced, on average, one ‘sexually satisfying event’ a month more than women given a placebo treatment. According to the FDA, between 8 and 13 percent of women who take the drug will see some improvement2. This is a pretty small number, particularly when that improvement might amounts to only one satisfying experience. So flibanserin is in no way a woman’s Viagra.
Equally worrying are the drug’s potential side effects, which include drowsiness, dizziness, fainting, and lowered blood pressure, all of which may be exacerbated if the drug is taken with alcohol, hormonal contraceptives, or any of the other medications many women rely on, such as anti-depressants. Dr. Adriane Fugh-Berman, director of the PharmedOut project at Georgetown University, has gone so far as to label Addyi “a mediocre aphrodisiac with scary side effects.”3
Then there is the issue of how much the drug costs. Viagra is taken on demand, making it fairly cheap, whereas Addyi must be taken daily, making it more expensive. Cash strapped public health services like the UK’s National Health Service, which already put sexual satisfaction low down the list of patient priorities, are less likely to adopt the drug, particularly given its lacklustre trials performance and apparent side effects.
For all the above reasons, Addyi is no Viagra. It works differently, is less effective, has more side effects and costs more. Moreover, it will not match Viagra as a means to rejuvenate sexual performance in later life; Addyi is for premenopausal women only. As it is taken each day to improve desire, rather than when sex is anticipated, Addyi is not going to be used recreationally like Viagra, taken by guys who suffer no dysfunction but just want to lengthen their performance. Some women also report that Viagra improves sex, although as the drug is not licensed for use by women research is limited on why this might be the case.
If Addyi is notable for one thing it is the lobbying campaign that was conducted to get FDA approval. Sprout Pharmaceuticals, who bought the rights to the drug after it failed its anti-depressant trials, hired a clever PR agency, Blue Engine Message & Media, to market the drug as a treatment for women with desire dysfunction. Blue Engine identified the lack of drugs for female sexual dysfunction as an FDA blind spot and set up an “independent” campaign organisation, Even the Score, that was successful in gaining backing from influential US women’s groups and sexual health bodies. The icing on the cake was to colour Addyi pink to complement the little blue pill that it so clearly is not. The irony of using such a gender stereotype to push a self-proclaimed “feminist” campaign seems to have escaped most commentators.
So once again we have a drug company pushing a treatment for commercial as much as scientific reasons, and critics have charged that this is a Big Pharma plot to medicalise female sexual problems. Of course, as most sex therapists are only too well aware from their clients’ experience, low desire, lack of arousal, weak erections or premature ejaculation can as easily be attributed to non-medical causes such as anxiety, relationship difficulties, depression and any of the other stuff that life throws at us and which unbalances our physical functioning. Talking treatments can often be as effective as medical interventions.
The sad truth is that Addyi’s marketeers are right in one important fact. Female sexual desire is under-researched and less understood than the mechanics of the male erection. But how men’s brain chemistry changes in arousal is as little understood as the process in women. Addyi might yet be found to work for some men who have low desire, and Viagra might well have some positive impact on female sexual experience.
The champagne corks may be popping among shareholders of Sprout Pharmaceuticals, but the likelihood is that after an initial surge of prescriptions most women will decide that Addyi’s limited effectiveness is not worth the expense or the safety issues. For those women for whom Addyi works, the FDA decision is good news. But Addyi is unlikely to do for women what Viagra did for men with erectile difficulties.
- “5 reasons to be sceptical of the new ‘female Viagra’ ”http://www.vox.com/2015/8/18/9173067/flibanserin-female-viagra-science