I came up with what I think might be an interest rules module for addiction and drug use in D&D Next. Take a look and let me know your thoughts - http://worldbuilderblog.me/2014/05/29/orange-spice-2/
Note: This isn't meant to make light of addiction or drug use or the drug trade. Just a mechanic for trying to introduce it into the world to help with realism. I play with all adults in my campaign.