Scientists have made a breakthrough that could lead to the availability of a male contraceptive pill. The discovery uses a peptide that changes the way human cells work. It "switches off" sperm's ability to swim, rendering men temporarily infertile.Scientists hailed the results as "startling".The effect of the new contraceptive is almost instant.It raises the prospect of a fast-acting pill or a nasal spray that a man could pop or inhale hours or even minutes before sex.Women are typically advised to stop taking the pill weeks or even months before trying to conceive. But researchers believe the effects of a male pill would happen almost instantly, with effects wearing off within a matter of days.Lead researcher Professor John Howl, of Wolverhampton University, said the new compound had shown immediate results."When you take healthy sperm and add our compound, within a few minutes the sperm cannot move," he said.Working with scientists from Portugal, the team made a compound called a cell-penetrating peptide.Peptides are short chains of amino acids that influence how human cells work. They occur naturally but can be synthesised.Howl said it was "too early to say" whether the result would be a pill, a nasal spray or a sub-skin implant, but said all were possibilities.Research suggests that about half of men would consider taking a contraceptive pill. ..