Just an idea but could you go to the doc with him when he gets his scripts then take him to the pharmacy to be filled and then secure them in a small safe and dispense the meds to him?
If he needs them this may be a way to help him control them. Him compuslivly taking them could be just a symptom of the ADHD. On the other hand you would need to keep an eye out to be sure he is not supplimenting what you give him with either ritalin etc bought on the street (common on larger college campuses I hear) or worse yet supplimenting with meth.
Talk to him if you can to see why he takes them in excess. It may be a problem that can be simply solved with a bit of guidance and control from you.
Hopefully your situation's been resolved or at least improved since you posted this comment; if not I hope that my comments can be of some service to you.
I have a friend that has been a stimulant junkie since his teens. He is ADHD (like me) but his was always completely out of control. I don't know what your son went through in childhood, but being told no, stop don't etc etc your entire life gives you some motivation to dabble in the less acceptable lifestyle of social recluse: drugs. stimulants are like a flavor that some people simply prefer.
All this to say that my friend abused and still abuses (from my unprofessional opinion of course) drugs, prescribed and not, because he found comfort in something he had at hand very early on that was consistently making him feel better. It's like the comfort blanket for people that have never been allowed to fit in with the rest of the group because we're either different, annoying, obnoxious or accidentally disrespectful to others as a result of ADD. ADD doesn't just affect a person then get treated, bear in mind that our socialization in learned in childhood predominantly and being medicated affects a person to varying degrees.
Best of luck, best wishes and hopefully he comes to terms with what he wants to get out of life and realizes that drug abuse doesn't fit in very quaintly with achieving most goals.
I'm sorry nobody has answered your call for help! Hopefully somebody here is familiar with Concerta. We are all addicts or are loved ones of addicts trying, as you are to get help.
First of all, please realize if your son is taking too much of the medication, and exhibits exaggerated behavioral changes, then there is a problem -- regardless if he's addicted or not. This is at the very least an indication that he's abusing this medication, not necessarily that he's addicted to it.
Have you ever asked him WHY he's using more than the rx'd dose? What does it do for him? Are you sure this is the only thing he's taking? Does his behavior match the description of taking excessive amount of the drug?
I would never recommend kicking him out as he obviously has a problem. I think it would help tremendously to find out why he is using more. Can you do that without him getting defensive?
Again, I'm not familiar with that particular drug, but any medication taken in excess, or taken any other way than which it is directed indicates a problem.
Keep posting and hopefully somebody here knows more about this drug.
Best of luck to you!!