Well, the concrete answer is the DEA. The idea is to discourage people from using these medications to get high in the first place. About 10% of them will get addicted. Getting high is one thing. Addiction is something else completely. Ask anyone who has grown up with an addict or alcoholic... Besides, once people are addicted, their health is really not their primary concern. They share needles, work as prostitutes, commit robbery, drink methanol. To believe that removing the compounding agent is going to stop addicts from hurting themselves is naive. Sometimes the line between enabling and harm reduction overlaps. There is no right answer. As an aside, I've never seen someone with tylenol toxicity (other than suicide attempts) who wasn't an alcoholic, an addict or both. The last person I saw with this had a broken jaw from her abusive boyfriend. The two of them hit every ER in the state getting Lortab. They had quite a party along the way. By the time I saw them, she was bleeding out of every orifice, with fulminant hepatic necrosis. (She didn't make it to transplant.)

I've worked in a liver transplant unit, which is where Tylenol poisoned patients land... The whole idea is to make drugs like vicodin toxic in high doses and lethal IV. These are called "Compounded" drugs. They have a maximum dose, over which it becomes toxic. Drugs like oxycontin have no maximum dose (if you are adequately physically tolerant to opiate drugs) It's like similar to the practice of adding an adulterant (e.g. isopropanol, methyl ethyl ketone, methanol, etc ) to ethanol to make it undrinkable. In addition to Tylenol, atropine and aspirin are used as adulterants. The theory is that they will have less value to opiate addicts and it works. Compounded drugs are worth less on the street than uncompounded drugs. Almost Invariably, people who OD (not counting suicide attempts) on the Tylenol portion of a compounded drugs are abusing it. Furthermore, they are usually malnourished alcoholics who already have underlying liver disease... Last of all, most people aren't as susceptible to Tylenol toxicity as the people who get into trouble. I've seen quite a few addicts who were downing 40 pills a day of percocet or vicodin, with no ill effects.