A contraceptive pill for men is a step closer to reality
following a discovery by US scientists.
Researchers found a compound called JQ1 disrupts the
development of sperm, decreasing sperm count and mobility.
But in a crucial finding, the effects of JQ1 are reversible.
Mice given the drug became infertile but when treatment
stopped, sperm production returned to normal and healthy
offspring were conceived afterwards.
There was also no impact on testosterone production or sex
The study, published in the journal Cell, concluded that
although the drug had been tested in mice it would probably
work in humans due to reproductive similarities.
"These findings suggest that a reversible, oral male
contraceptive may be possible," said study author Dr James
Bradner from the Dana-Farber Cancer Institute in Boston.
Australian male fertility expert Professor Robert McLachlan
said the researchers had targeted a factor in DNA remodelling
that was essential for sperm production, blocking the cell
division necessary to produce normal sperm.
However, he said lengthy research would be needed in animals
before it could even begin tests in humans.
"The development of a potential contraceptive is a very long
and arduous process leading up to the first human studies,"
said Prof McLachlan, the director of clinical research at
Prince Henry's Institute in Victoria.
He said not all of the mice had sperm counts reduced to zero,
and for the drug to be useful it would need to proven to be
almost universally effective.
Although the reproductive systems in mice and men were
similar, proof was needed in human sperm production.
"Research will need to confirm the authors' assertion that
the drug is free of adverse effects on other tissues and that
it is fully reversible," Prof McLachlan said.
"Ultimately, the compound will need to face the challenge of
male contraception efficacy trials involving hundreds of
couples over several years in order to assess its true
effectiveness," he said.
He said the evaluation process could take around 15 years.
The authors, including Dr Martin Matzuk from Baylor College
of Medicine, acknowledged there would be concern that
targeting male cells would result in irreversible toxicity or
However, they said only full recovery was observed in the
"We envision that our discoveries can be completely
translated to men, providing a novel and efficacious strategy
for a male contraceptive," the study said.
The JQ1 compound was originally made at Dana-Farber to block
a cancer-causing gene and has proved effective in laboratory
tests of lung cancer and some blood cancers.