Now you can have what she's having...

Doctors testing a new anti-depressant have found it unexpectedly effective at boosting the female libido. Photo / Herald on Sunday

As the old joke has it, men can be turned on with a simple flick of a switch while women require attention to a battery of dials and buttons. Today the debate over how to stimulate female sexual desire is set to be reopened with the discovery of a drug described as "Viagra for women".

Doctors testing a new anti-depressant found it was useless as a mood brightener but was unexpectedly effective at boosting the female libido.

Now three clinical trials have shown that the drug fibanserin significantly improved sexual desire and satisfaction in women.

The accidental discovery mirrors that of Viagra, which was being tested as a heart medicine in the 1990s when the male subjects prescribed it discovered it had a pleasing side-effect.

However, fibanserin is different in that it works on the brain rather than on the genitals, according to John Thorp, professor of obstetrics and gynaecology at the University of North Carolina. Doctors have long known that in women, the brain is the most important sex organ.

Professor Thorp, who led the studies, said: "It's essentially a Viagra-like drug for women in that diminished desire or libido is the most common feminine sexual problem, like erectile sexual dysfunction is in men.

"Fibanserin was a poor antidepressant. However, astute observers noted that it increased libido in laboratory animals and human subjects. So we conducted multiple clinical trials and the women in our studies who took it for hypoactive sexual desire disorder [low libido] reported significant improvements in sexual desire and satisfactory sexual experiences."

The results were presented yesterday at the Congress of the European Society for Sexual Medicine in Lyon, France. Previous research has suggested that between one in 10 and one in four women suffer from low libido, which varies with age and whether they are pre- or post-menopause.

But critics have claimed that drug companies have exaggerated the nature and extent of women's sexual problems to create new markets, and adopted too mechanistic an approach. While male sexual dysfunction is related to performance, in women there is no equivalent problem inviting a similar correction.

The feminist author and sex researcher Shere Hite has said: "It is not arousal pills we need but a whole new kind of physical relations. The pharmaceutical industry is guilty not just of cynical, money-grabbing exaggeration; it has misunderstood the basics of female sexuality."

Specialists in sexual medicine agree that the female libido is more complex and cannot be switched on or off in the same way as the male libido. But they claim women can respond to gentle hormonal stimulation.

However, Professor Irwin Nazareth, of the University College Medical School, London, said sexual dysfunction needed to be redefined. In a survey of 1,000 women in north London six years ago, he found that while 40 per cent reported a lack of or loss of sexual desire, only a quarter regarded it as a problem. "For many people, reduced sexual interest or response may be a normal adaptation," he said.

The trials of fibanserin, funded by its manufacturer Boehringer Ingelheim, were carried out with 2,000 women in the US, Canada and Europe, using four different doses of the drug. Only the highest dose of 100mg a day was effective. Women taking the 100mg dose reported having more frequent and more satisfying sex and greater desire. They were also less distressed about their previous sexual problems.

Professor Thorp said the only currently available treatment for low sexual desire in women was testosterone patches. Although testosterone is a male hormone, it is also produced in women at lower levels and plays a crucial role in sexual desire. However, it has unpleasant side-effects, including acne and facial hair growth. "These results point to a novel approach to pharmacological treatment of the sexual problem that plagues reproductive-age women the most," he said.

- THE INDEPENDENT