Narcotics - Pit of Despair (1967)

"John, a clean-cut high school senior, is targeted by Pete, a low-life drug dealer, as his next victim. Inviting John to a party, Pete introduces him to big-breasted Helen. Told to "blast off for Kicksville" by smoking a joint, John proceeds to do just that. He is immediately turned into a marijuana addict, and shortly thereafter starts shooting up heroin." -imdb.com