No such thing. The only way to prevent an hangover, is to not overindulge on alcohol.
Some tips though - make sure that you eat a good meal before you drink, so that there is something substantial in your stomach to help absorb the alcohol. Space your drinks out, drink water in between, so you don't get dehydrated. Eat a snack at some point as well, if it's been more than a couple hours. Take an Advil or Tylenol when you go to bed too, sometimes helps.