NZT-48 is a fictional drug that appears in the movie and TV series "Limitless". In the show, NZT-48 is a nootropic drug that enhances human memory and intelligence while acting as a nearly perfect antidepressant and anxiolytic. However, in reality, NZT-48 is not a real drug. While there are real-life nootropic drugs that can enhance cognitive function, such as modafinil, there is no drug that can provide the same level of cognitive enhancement as portrayed in "Limitless".