HORMONE replacement therapy could hold the key to creating a male contraceptive pill, say scientists from Leeds General Infirmary.
Researchers looked at compounds used in HRT and the female Pill and their effects on men when used alongside testosterone.
They found that tibolone and nomegestrol acetate (Noma) - synthetic progestins used in HRT - seemed to have a contraceptive effect in men.
But the team, together with scientists from Manchester University, said it could be more than 10 years before they were available for use.
A number of trials are under way into alternatives to the contraception options currently open to men - condoms, vasectomy and abstinence.
The latest studies, led by Prof Fred Wu, found that tibolone and Noma suppressed pituitary gonadotrophins, the hormones that stimulate the production of sperm.
Trials are continuing to see if the compounds suppress sperm production, as expected.
Researchers said that Noma showed particular promise, as it had no adverse metabolic effects.
Other male contraceptive formulations in production have cut good HDL cholesterol levels, which protect against heart disease.
Noma did not have this side-effect in the men who took part in the trial.