April 01, 2004
Viagra May Reduce Male Fertility

Viagra may use up an enzyme used by sperm to penetrate an egg.

Viagra seems to speed up the acrosome reaction, so that by the time the sperm reaches the egg it has no digestive enzymes left to penetrate the outer layer. Sperm that have undergone this process are known as fully "reacted".

The researchers tested 45 samples of semen. They found that up to 79% more sperm were fully "reacted" in samples treated with Viagra.

Some experts say that past clinical trials done on humans didn't find any harmful side-effects from Viagra.

This fertility finding contrasts with human data from clinical trials: Viagra’s effect on sperm movement and function was extensively studied, says Larry Lipshultz of Baylor College of Medicine in Houston, Texas who has been involved in trials of Viagra and its competitors, Levitra and Cialis. "I've reviewed all the data and never seen a fertility problem," he says.

However, this team has done follow-up work which found this effect on men.

The team is now studying the effects of Viagra on the sperm of men actually taking the drug. The initial findings in 17 men show Viagra does speed up sperm.

It is interesting to note that some men whose sperm fail to fertilize in convention IVF may have insufficient acrosome activity. So the use of Viagra by men who are trying to use IVF to start a pregnancy may be making their existing cause of the need for IVF even worse.

Most sex is for reasons other than reproduction. But these results suggest that those intending to start a pregnancy and those who are not adequately protecting against the possibility of pregnancy ought to think twice about using Viagra. Certainly if you are going to try to do IVF think twice about using Viagra to help get the sperm sample.

This work obviously needs to be repeated for Levitra and Cialis as well.

Share |      Randall Parker, 2004 April 01 05:31 PM  Biotech Reproduction

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