I have taken both drugs...the Avinza is extended release Morphine while the Opana is extended realease oxymorphone. The Opana makes me feel horrible, even before I get to my next does which is every 12 hours I am absolutely miserable. Makes me very fidgety, and nervous, sleepy, constipated (which is totally normal with any of these drugs), depressed, and severe headaches. It does take the edge off of my pain but certainly does not take the pain away. The Avinza made me very very sick. I am 33 with RSD of the right arm for a little over two years now, I hate being on meds at all so I can be a little negative on the whole subject. I held my 7 yr old son while he died from a brain tumor 3 years ago and the meds just took a toll on his little body. My main advice is that no matter what any of us tell you, everyone reacts differently. These medications may be a godsend to you, while not helping someone else at all....if you have a good doc see if you can try it for a while, but if it does not work he will change you immediately...there is no point in anyone being miserable from a medication when there are others available.