Does he have any other symptoms?
Like being irrational or impulsive ect?
Have u spoken to his family and has he had life long issues with anger/temper.
My ex abused booze also kinda self medicating I suppose.
Good luck at least he sees he has a problem and is trying to get help, getting someone to see that is the hardest part (my ex finally realised when I left for good).
Drugs won't help if it's just anger he needs to talk to someone and work out coping strategies.