To be taken once a day, if approved (Image: Allen Breed/PA)

The first drug to treat low sexual desire in women may get approved in the US today. Find out why not everyone is rooting for it.

What’s all this about the new female Viagra?

It’s a drug that’s designed to boost women’s desire for sex. It’s called flibanserin and the US Food and Drug Administration is set to decide today whether to let it go on sale.

It doesn’t work in the same way as Viagra though – women would have to take it every day, whether or not they want sex. And, while the famous little blue pill works by increasing blood flow to the genitals, this new drug instead alters brain chemistry, affecting receptors for various signalling chemicals including serotonin and dopamine. In fact, it was first developed as an antidepressant before it was found not to work for that condition.


How well does it work for low libido?

Not amazingly. In tests it led to couples having sex – or other “sexually satisfying encounters” – an average of once a month extra, from a baseline of two to three times a month. And there are side effects: it can cause sleepiness, sudden drops in blood pressure and fainting, especially in combination with alcohol. As the FDA puts it, the drug has a “challenging benefit/risk assessment”.

So why does it have so many cheerleaders?

A well-funded PR campaign was certainly a factor. Manufacturer Sprout Pharmaceuticals has enlisted various women’s groups to present this as a feminist issue, pointing out men have drugs like Viagra, but nothing exists for women with low sexual desire. The FDA denies it is sexist, but Sprout says it’s time to “even the score”.

Do they have a point?

It would be a most unusual reason to approve a medicine, says Cindy Pearson of the National Women’s Health Network, one of the groups that has not backed Sprout’s campaign. “It’s really frustrating to see a company fail on the data and try to claim gender bias to distract from that.”

When doctors decide if a drug should go on sale, they are supposed to carefully weigh up its ability to alleviate a disease or condition along with the risk of side effects and the harm accrued by letting the condition go unchecked. Pitting it against other drugs designed to treat a different medical condition that affects a different group of people is invalid, says Pearson.

And these are very different conditions. Impotence in men is often caused by lack of blood flow to the erectile tissue in the penis – a problem of faulty plumbing, you might say – that can easily be corrected by Viagra and similar drugs.

If women go off sex, on the other hand, that’s no plumbing problem. It could stem from a host of complex factors, including relationship problems, busy lives and the ageing process.

Some say it is so common for women to be less interested in sex than their partners that it should not even be classed as a medical condition. It’s unsurprising that the pharmaceutical industry is finding this a tough nut to crack.

So this isn’t the first attempt?

No. The first female Viagra was, in fact, regular male Viagra. Manufacturer Pfizer, flushed with their initial success, tried to expand its use to women. It turned out that the drug does increase blood flow to women’s genitals, but this has no effect on their libido.

Then testosterone patches were tried, as there is some evidence that low sexual desire in women can be caused by a lack of this hormone, but they were not approved either.

Which way is today’s vote likely to go?

We will have to wait until late on Thursday to hear the advisory panel’s decision – which the FDA usually follows. The sticking point may be the risks of combining the drug with alcohol. The FDA said earlier this week that its panel must look at whether people taking the drug should be told not to drink – and whether that is feasible “taking into account the prevalence of alcohol use in the US”.