Men Who Take Viagra
'Put Their Fertility at Risk'
ROBIN McKIE/ The Observer (UK) 24feb2008
Using Viagra may be damaging men's fertility, researchers have warned. Experiments suggest that the anti-impotence drug can harm sperm and may prevent some men from fathering families.
In particular, young men who use the drug recreationally could impair their ability to have families. And fertility clinics that prescribe Viagra to help men produce sperm for IVF treatments could be preventing some couples from conceiving.
'I think it is worrying that some IVF clinics are using Viagra in order to boost fertility results,' said Dr David Glenn, a consultant gynaecologist at Queen's University Belfast. 'Couples that go there for treatment are, by definition, already having problems getting pregnant. Giving male partners something that could make the problem worse is scarcely the right approach.'
Glenn's research, which is to be published in the journal Fertility and Sterility, is based on two sets of experiments. The first involved taking sperm samples from volunteers and then bathing them in weak solutions of Viagra. The aim was to produce a Viagra level equivalent to that found in the blood of a man who had taken a single 100-milligram tablet.
The researchers then compared the behaviour of the treated sperm with standard samples and found the drug had two principal effects. It made sperm more active but also it damaged its acrosome, a cap-like structure that contains enzymes that break down the membrane surrounding a woman's egg and allows sperm to fertilise it.
'Essentially the acrosome breaks open too early in sperm that has been exposed to Viagra. The sperm cannot get into the egg and so it is not fertilised,' said Glenn.
His team carried out similar experiments on animals and found that sperm from mice that had been given Viagra produced 40 per cent fewer embryosthan those on control pills. However, there was no evidence that baby mice produced by male mice on Viagra had been damaged in any way.
'There are two main concerns raised by these findings,' Glenn told The Observer. 'First, Viagra has become a widely used recreational drug. It is mixed with cocaine, for example, and is sold in clubs. Our work leaves open the possibility that there could be a cumulative effect from taking Viagra, however, which could pose serious fertility problems in later life.'
Glenn's work also suggests that the use of Viagra by IVF clinics could pose problems for many couples. Last week The Observer contacted a number of British IVF clinics to ask if they administered Viagra to men. Several said they did. Others, such as the clinic at University College Hospital in London, said did not because it had been found that Viagra could damage sperm.
'Couples going to clinics already have fertility problems. Viagra may simply be making those worse,' said Glenn.
Additional research Charlie Francis-Pape