A drug that boosts women鈥檚 libido may have come a step closer after apparently successful trials.
Inevitably dubbed a 鈥渇emale Viagra鈥�, such drugs are objects of desire for the pharmaceutical industry, which sees them as a potential gold mine. However, flibanserin鈥檚 effects are modest, and the results have reignited the debate over whether 鈥渉ypoactive sexual desire disorder鈥�, which the drug claims to treat, is a real medical condition or a variation of normal human behaviour.
HSDD, defined as the persistent and distressing lack of sexual desire, is recognised as a form of female sexual dysfunction by clinicians, researchers and the drugs industry, but some doctors and therapists question it.
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Flibanserin鈥檚 manufacturer, German firm Boehringer Ingelheim, reported this week that women with HSDD taking the drug increased the average number of times they had 鈥渟atisfying sexual experiences鈥� from 2.8 to 4.5 times a month.
Placebo effect
However, this compares with an increase for those on placebo to 3.7 times a month. And unlike treatments for male impotence, which are immediate, flibanserin must be taken once a day and takes up to four weeks to have an effect.
Lih-Mei Liao, a clinical psychologist specialising in women鈥檚 health at University College London, says it is 鈥渧ery debatable鈥� whether the results represent a useful improvement. 鈥淎n effect that鈥檚 statistically significant may not be clinically meaningful.鈥� Furthermore, she says the definition and assessment of sexual disorders such as HSDD 鈥渃ould be overly subjected to the influences of the pharmaceutical industry鈥�.
Since the runaway success of Viagra and other drugs to treat male impotence, the pharmaceutical industry has put considerable resources towards producing a drug to increase women鈥檚 libido. The two are not strictly comparable, though: Viagra-type drugs are designed to treat erectile dysfunction by increasing blood flow to the penis and do not increase desire.
Complex mix
By some estimates, around 40 per cent of women are dissatisfied with their sex life. But many sex therapists argue that women鈥檚 lack of desire is usually caused by a complex mix of personal, relationship and societal factors, so a pharmaceutical fix is the wrong approach.
It鈥檚 not clear how flibanserin works, though in animals it seems to alter levels of three signalling molecules in the brain, increasing dopamine and noradrenalin and decreasing serotonin. Boehringer Ingelheim was originally investigating the drug as an antidepressant when female testers reported raised libido.
This week the firm from four large trials involving 1378 women at a meeting of the European Society for Sexual Medicine in Lyon, France.
While the increase in sex was small, the effect is worthwhile, according to one of the doctors who conducted the trial. John Dean, a sexual health specialist at Newton Abbot Hospital in Devon, UK, who has also been a consultant for Boehringer Ingelheim, says: 鈥淚 have seen women have significant improvements in their sexual interest.鈥�
If the drug is granted approval, it may go on sale in one to two years.
