Levitra, Glaxo's answer to Viagra, allows men to enjoy 12 hours of sexual prowess, according to a new test.

This is three times longer than anyone had expected. Glaxo researchers are calling the drug 'the all-nighter'.

They have just carried out tests on 1,500 patients.

The world market for erectile dysfunction (impotence) is worth over $3 billion, and it is growing fast.

The pill starts to work in 15 minutes. This makes it the fastest working drug of its kind.

Glaxo expects the drug to hit sales of $1 billion a year.

Glaxo is has been selling Levitra in the US with Bayer pharmaceuticals for one year.

They recommend taking Levitra 25-60 minutes before sex. There is a World Congress on the Ageing Male in Prage, Czech Rep., today where they will reveal their test results.