Opana (oxymorphone) is a much more potent narcotic than oxycodone is. It's likely that they have a very similar side effect profile intensity at equianalgesic doses - unlike morphine based drugs, which tend to have a significantly more intense side effect profile - everything from histamine-related effects to euphoria - it's all more intense with morphine and it's salts (morphine sulfate, morphine diacetate (heroin), morphine dinicotinate (nicomorphine), morphine hydrochloride, morphine citrate, etc) and other morphine-related drugs like hydromorphinol, desomorphine, dihydromorphine, etc.
I'm closing this thread as it has no HR value and will not lead to productive discussion. The answer to the question is simple and it has been answered.