Assuming it is any of the following and as people say 4.5oz is alot
Cocaine and crack are Class A drugs - illegal to have, give away or sell. Possession can get you up to seven years in jail. Supplying someone else, including your friends, can get you life and an unlimited fine.
Heroin is a class A drug. This means that possessing it can lead to a prison sentence of up to 7 years and an unlimited fine. Supplying (which includes giving it to a friend) could lead to a life sentence and another unlimited fine