I do not believe there is any DEA regulation concerning daily useage of schedule drugs. While state have instituted a data base that tracks the dispensing of controlled substances, it is used for finding forges scripts and scripts from a drug mill. I guess everyone will have to use injectable Fentanyl, that is measured in mcg, so 500mg will just kill you.
I am guessing that when the primitive showed up at CVS with a couple of scripts, one for oxycodone, one for morphine SR, the pharmacist said, you know taking this much will kill you, I am not going to fill it till I talk to the doc. Therefore, because someone used their professional training there is a new "regulation" in place. The DEA does not usually get down in the weeds to determine total daily dose of a narcotic cocktail, because as people do use them over a long period of time, their tolerance goes up. We have hospice patients on Fentanyl IV, at such a high dose, it would put a normal person down for days, these folks can communicate, eat and walk. It is friggin amazing.