It sounds like the OP wants to spike a drink for him, in order to make him pass out because he is annoyed. Not only is this very wrong, it could potentially kill him, because you do not know what drugs are in his system, and if you give him anymore sedatives on top of heroin, he could suffer from respriatory failure and die.
You sound like quite an asshole. You are willing to risk someone else's life just for your own comfort and peace. I'm sure glad you are not my roomate. I hope that our assumptions about this are wrong, cause if not, you just need to live alone and not fuck with what drugs people put in their body. If he is annoying you or making downright impossible to sleep and live with, then just try and calm him down and talk to him. Ask him if he can please just take a break and recoup for a few days, or take his partying and crazy behavior elsewhere until he returns to a somewhat normal state.
I believe this thread needs to be closed and maybe deleted, if possible. Some of the suggestions people are giving this egotistical douchbag could end up costing his roomates life.