A NEW contraceptive that promises to make long-term birth control more acceptable to men is to be tested in Scotland.
Previous attempts at popularising the male "pill" have foundered because, although effective, they have involved weekly injections. But a new combination of hormones means that the jabs now only have to be administered once every two months.
Scot
tish couples are now being urged to come forward to help researchers trial the new method, which stops sperm production. The bi-monthly jab combines testosterone and progesterone. The addition of the progesterone hormone makes it possible to use less testosterone and also helps make the effects last longer than previous versions.
The team are now searching for 20 couples in south-east Scotland to take part in a one-year international trial involving 200 couples, run by the World Health Organisation.
Professor Richard Anderson, from Edinburgh University's reproductive and developmental sciences division, said a previous study in Scotland with the weekly male jab had shown that such a method worked.
"That was extremely successful and proved the concept that an injectable hormone could stop men's sperm production to very good contraceptive levels and be fully reversible," he said. "It was a proof of concept rather than anything that was ever going to be used, but it did prove that it could be done.
"What we are doing now is a substantial refinement of that, using the same theoretical approach of hormone injections that temporarily stop men producing sperm. The idea is to check that it really is a good contraceptive."
The new study will recruit men under the age of 45 with female partners under 37, with regular periods and no medical reason preventing pregnancy.
Tests have shown that the injection reduces a man's sperm count down from above 20 million sperm per millilitre to zero in most men, and to less than one million in others.
Such as result would provide better contraceptive protection than condoms, and a similar success rate to the female pill.
"Many of the couples we see for this type of study will be those with existing contraceptive problems who recognise that although theoretically there are a lot of options, you can run out quickly," Anderson explained.
But would men want the jab even if it were available in a more usable form? Anderson said he was in no doubt that there would be market for the male jab. "The surveys we have done have been very positive and particularly positive from women as much as men.
"You are in a stable relationship. You have had a baby or two. You have taken the reproductive burden on throughout. Maybe it's about time someone else took a turn."
Anderson said it was too early to talk about side-effects, but no serious problems were expected. Other hormone related treatments, such as the pill and hormone replacement therapy (HRT) have been linked to certain cancers.
"The risks with things like HRT and the pill are emerging after tens of millions of women have taken them for decades," he said. "These have shown that the risks, while real, are very small and take a vast amount of exposure to come to light."
A spokesman from the Family Planning Association said: "It is important that research continues to try to give men more contraceptive choice. But it is crucial that any new contraceptive is rigorously tested to make sure it is incredibly safe and effective."
• Couples interested in taking part in the study should call 0131-242 6196 or e-mail j.george@hrsu.mrc.ac.uk.
