The Mind of Henry Lime (2007)

Henry Lime sells security fences to the rich and famous in Beverly Hills. His mind isn't what it used to be: he can't sleep, can't concentrate, can't sell. He sees a new TV ad for a prescription drug called Lazarine. He takes it and it works like a charm - but has a slight side-effect: a hallucination by the name of Amanda who won't go away and is determined to help Henry, no matter how much trouble she causes.