The Black Vault

I think it was a late 80's movie. Straight to VHS.
It was him and some others from the brat pack.
He has some drug issues in that movie that lead to certain circumstances.

Clay is Andrew McCarthy and Downey is Juillian.

Here's the IMDB summary:
Clay, an eighteen-year-old freshman, comes back from his first term at a college in New Hampshire to spend his Christmas vacation with his broken-up wealthy family in Los Angeles. His former girlfriend, Blair, is now involved with his ex-best-friend, Julian. She warns Clay that Julian needs help: he is using a lot of cocaine and has huge debts. What follows is a look at the youth culture of wealthy post adolescents in Beverly Hills with a strong anti-drug message. Apart from the setting and the names, the film has very little to do with Bret Easton Ellis's book by the same title on which it was based.