Requiem for a Dream is a superb movie that came out in 2000. It's about two friends, Ty and Harry, and Harry's girlfriend, as they get into the drug business. It's also about Harry's mother Sarah who starts using amphetamine diet pills prescribed by a doctor so she can lose weight.
The description doesn't do credit to what is an absolutely stunning movie, one which is sure to put you off using Class A drugs. The director Aronofsky also was the first to almost use 'stop motion'-like, smash cuts to depict drug use. It's an incredibly thrilling and depressing movie, and also the year 2000 (really before smartphones and social media) looks like a different world.
Here is a short excerpt, but I encourage you to go and find the full version and watch it ASAP if you want to see a great movie.
Find out how.