'Side effect free' male pill

The drug works by disrupting sperm production

A drug used to treat the rare genetic disorder Gaucher's disease may also work as a male contraceptive.

Scientists believe the drug, which severely damages sperm, may be free of the side effects associated with hormone-based treatments currently in tests.

Anything that could be added to the menu of available contraceptives would be an extremely welcome

Dr Aarnoud van der Spoel

They administered the drug, which is used to treat Gaucher's, to male mice.

It had no effect on sexual behaviour, but rendered the mice completely infertile.

And it appeared to work at doses 10 times lower than those used for Gaucher's patients.

The researchers believe the drug, NB-DNJ, works by disrupting the way the body processes compounds called glucosphingolipids.

These compounds are made up of sugar and fat, and play a crucial role in sperm formation.

Defects

The sperm of mice treated with the drug exhibited a number of defects. In some cases their tails were wrapped round the head of the sperm, preventing it from moving properly.

The drug also caused a large increase in the number of defective acrosomes, tiny organs that help sperm penetrate the egg's protective coating.

NB-DNJ had no effect on female fertility, and once males were taken off the drug, the effect was fully reversed.

In addition, the drug had no impact on levels of the male sex hormone testosterone which is needed to maintain sex drive.

Other hormone-based contraceptives currently being tested cause testosterone levels to drop.

This means men who take them may also have to take hormone replacement therapy, which can have undesirable side effects.

Lucky stroke

Lead researcher Dr Aarnoud van der Spoel, of the Glycobiology Institute at Oxford University, told BBC News Online the contraceptive qualities of the drug were discovered by chance.

He said much more research would be needed before the drug was made available to patients, but that it had already been shown to be safe in tests on Gaucher's patients and this may help to speed up the process.

"The advantage is that this drug does not influence the sex hormone production of the male in the way that hormonal treatments do.

"But those treatments have been tested and shown to work in humans, albeit with side effects.

"At the moment we have no evidence that our drug works in humans.

"However, anything that could be added to the menu of available contraceptives would be an extremely welcome development as there are all kinds of reasons why some people do not want to use the methods that are currently available."

Gaucher's disease is an inherited metabolic disorder which causes, among other symptoms, enlargement of the liver and spleen.

The research is published in the Proceedings of the National Academy of Sciences.