Viagra gum to 'double your pleasure'

A supercharged chewing gum may one day be on the market - containing the active ingredient in the sex-enhancing drug Viagra.

Chicago-based Wrigley, whose slogan is "Double Your Pleasure", has filed a patent to sell Viagra in gum form.

Each stick would contain from 5mg to 100mg of Viagra's active ingredient, sildenafil citrate.

But the gum will not be available any time soon: drug company Pfizer's patent on Viagra runs until 2011.