helping a friend with alcohol problems

I figured since this topic to related to addiction, I could ask here. My best friend has been struggling for a long time with over drinking and he is currently on several perscription drugs for health issues and depressions. I know if I question him too much on his drinking problem he's gonna get defensive which I don't want. I don't know what his drinking is like during the week but once the weekend comes, he loves to let lose and drink how ever much he wants. I rarely see him now a days as we've grown and hes met someone which has been an unhealthy relationship and we both work alot. I've been wanting to get away from the bar scene and do more outdoor things like hiking which don't interest him but I want him to experience it. I figured if I ask he'll say no. We just hung out tonight got food has some beers and played darts and brought back some food for his girlfriend once she got home from work. She had homework to do and was upset to see he was noticeable drunk. I'm there on the side lines listening to them argue and I don't know who's side to take. I can understand where they're both coming from and I want to help but I've been at a lose on how to approach it. He has been dealing with a deep depression for a long time from his family history and I feel the drinking has been a way for him to escape from that plus his unstable relationship with his girlfriend. Its a very complex situation and I care deeply for my long time friend. Even though we have started to go on different paths over the last 5+ years every time its just me and him hanging out, its like long lost friends catching up again on things and having a good time. I consider him almost family and I worry when the day will come that his health or his mental state has declined so much it may kill him. I hope anyone with experience can offer some advice.