Codeine isn't OTC in the US, even when mixed with acetaminophen. Though, from what I understand, a pharmacist technically has the ability to dispense codeine-containing cough syrup without prescription.
Also, Hydrocodone (derived from codeine) is a Schedule 2 drug in the US. But, when combined with another substance (most often with acetaminophen, like Percocet) the drug is reduced to Schedule 3. http://en.wikipedia.org/wiki/Hydrocodone
As far as addicts misusing OTC codeine/acetaminophen, it's apparently pretty easy to filter most of the adulterant in a basic kitchen.
Also, Hydrocodone (derived from codeine) is a Schedule 2 drug in the US. But, when combined with another substance (most often with acetaminophen, like Percocet) the drug is reduced to Schedule 3. http://en.wikipedia.org/wiki/Hydrocodone
As far as addicts misusing OTC codeine/acetaminophen, it's apparently pretty easy to filter most of the adulterant in a basic kitchen.