'Male contraceptive pill' successfully limits sperm activity without side effects, scientists find

Scientists have successfully tested a "male pill" which limits the activity of sperm without causing any side effects.

The drug known as EP055 was given to rhesus macaque monkeys during a study at the Oregon National Primate Research Centre in the US.

It works by targeting a protein on the surface of sperm limiting its ability to move.

"Simply put, the compound turns-off the sperm's ability to swim, significantly limiting fertilization capabilities," said lead investigator Michael O'Rand.

"This makes EP055 an ideal candidate for non-hormonal male contraception."

The only options for male contraception available at present are condoms or a vasectomy, but it is hoped that safe and reversible drugs could be available within a decade.

Other potential male contraceptives target the production of sperm - but these normally affect hormones just like female contraceptives.

In 2016 a male contraceptive injection was found to be effective but with a high side effect rate which led to the trial being halted early.

Just under half the men involved in the study reported developing acne, a fifth reported mood disorders and around 5 per cent did not recover their sperm count one year after taking the drug.

Another compound known as JQ1 was successfully tested on mice but it remains to be seen whether it would be effective in men without causing fertility problems.

Other studies have involved ouabain, a substance traditionally used by African hunters for poison on their arrows, and compounds from plants and mangoes.

This month clinical trials are due to start on the first-ever contraceptive gel, which dramatically reduces sperm count in men. The trials are due to last four years, however.

All the macaques involved in the EP055 study showed signs of complete recovery 18 days after being given an infusion.

The study concluded: "Overall, EP055 had no long-term effects on any of the animals.

"Although EP055 has not yet been tested in a human contraceptive trial, our data indicate that it has a strong potential to be a male contraceptive that would provide a reversible, short-lived pharmacological alternative to condoms or vasectomy."