first of all, good for you in getting clean (and moving out of that atmosphere!)and welcome to PC!!
unfortunately there is little else you can do regarding your friend. if he hits a bottom tho you can be there to support him if he decides to get clean and sober too.
as for the pdoc, he won't be able to discuss anything with you at all regarding your friend cause it's confidential. i guess you could write a letter to the pdoc tho and tell him what you know about your friend. that way he doesn't need to respond, which he can't do anyway.
i'm sure someone else may have some helpful suggestions but that's all i can think 'bout that you can do at this time.
sounds like you are one heck of a good friend. by your keeping clean you are living by example. let's hope he hits a bottom so you can help him get help. (follow the suggestions of NA tho and don't try to get him help without another NA member there with you).
meanwhile just remember "people, places and things". you're on the right path to staying clean!!!