Self-administration, drug discrimination, and repeat-dose two week dependence liability studies were conducted to compare hydrocodone to the prototypical opiates, morphine and oxycodone.
Hydrocodone was self-administered, produced an opiate-like subjective discriminative generalization profile and produced a significant discontinuation syndrome following abrupt treatment cessation that was quantitatively and qualitatively similar to morphine and/or oxycodone.
Hydrocodone has abuse liability more similar to Schedule II opiates than other Schedule III compounds currently controlled under the U.S. Controlled Substance Act.