A PILL for men could be closer – offering hope of new birth control options.
A non-hormonal drug was 99 per cent effective in preventing pregnancy in lab tests on mice.
Human trials may start by the end of the year, with the possibility of coming to market in five years or less.
Most such drugs undergoing trials target the male sex hormone testosterone. But this has shown side effects of obesity and depression.
Lead author Abdullah Al Noman, of Minnesota University, US, said: “We wanted to develop a non-hormonal contraceptive to avoid these side-effects.”
It targets a gene that produces retinoic acid, a form of vitamin A that fuels sperm development.
Lab experiments have shown that mice without this gene are sterile.
The researchers created a chemical that blocked the gene, and when given to mice, it significantly reduced sperm counts.
After four weeks, it was able to prevent pregnancy in mice.
But promisingly, the mice were able to conceive six weeks after being taken off the drug.
No clear side effects were found. However, mice cannot report side effects like headaches or mood changes.
At present, there are only two forms of contraception for men – condoms and vasectomies.
Condoms can only be used once and are not guaranteed to prevent impregnation.
Vasectomies are a form of surgical sterilization that is expensive to reverse and is not always successful.
It has left the women with the responsibility, for the most part, to use birth control methods such as the Pill, the coil, and the implant.
The female pill also carries side effects, including blood-clotting risks.
But since women face becoming pregnant without contraception, the risk calculation differs.
Other scientific teams globally have been working towards a male contraceptive, incuding in the form of pills, injections and gels that are rubbed into the skin.