Pop superstar Madonna has been treating the sick stars of her husband Guy Ritchie's new movie by injecting them in the bottom with vitamins. The singer, who regularly uses the B12 vitamin herself, stepped in after a spate of illnesses on the London set of RocknRolla. Actor Tom Hardy - who stars in the film - made the astonishing discovery when he stumbled across the Material Girl treating co-star, 300 actor Gerard Butler. Hardy says, "She does it for her dancers, she trained doing it, so she decided to do it for the actors as well. "When we had a break Guy asked if I'd like to meet the wife as she was in the car park and he knew I was a fan. "To be honest I had the shock of my life. There she was in the back of her Range Rover administering a shot of B12 into the arse of Gerard Butler. Believe me. "I was completely stunned. I knew it would be magnificent to meet her but the last thing I expected to see was her giving Gerard a shot in the arse because he wasn't very well. "She was so cool. She just said to Gerard, 'There you go - bosh! That does it."