I am not comfortable with a subsitute.One thing though, when the time comes he will say you got to go to quest and take a drug test. The first time this happened I went to GNC and got a bottle of this grape juice stuff I can't remember the name of it. Drank it waited 2hrs and took the test and passed but at that time I think I didn't smoke for about two and a half weeks.Does anyone think this will work with only a 5 to 8 day time span. More info please.