Oxymorphone is much stronger then oxycodone. It has a crazy high affinity for the mu opiod receptor. It binds stronger then anything even buprenorphine. I was on 12mg a day buprenorphine when I was scripted them and found someone that thought opanas were the same strength mg for mg as oxycontin so they were selling the 40mg opana er for only 20 bucks.
Needless to say I thought meh might as well buy 5 of these I heard good things about em too bad i'll have to wait like 4-5 days b4 I can do it or the bup will block it. Well of course later that night I said screw it its been 20 hours since I took my bup I know its still in my system but some of it has to be out so I grinded a 40 into a powder using this water heater metal tie thing. Chopped that powder incredibly fine with a razor blade took about 20 minutes from start to finish. I had a very fine baby powderish consistency powder and blasted the whole 40mg opana.
Wowie i was incredibly wrecked it busted right through the buprenorphine kicked it ass off the receptors and had me noddin feelin great. Part of the reason was probly cause for the past 3 months buprenorphine was the only opiate I took so I didn't have much of a tolerance. This made me think maybe bup doesnt block your receptors, but a few weeks later i tried to do the same thing with an 80mg oxycontin and the subutex blocked it 95%, the oxycodone could not kick buprenorphine off the receptor but oxymorphone can.
For my body and my brain and receptors, Oxymorphone is the god of all opiates to me. Of all opiates I've tried, It feels better then fentanyl, hydrocodone, hydromorphone, methadone, oxycodone, codeine, morphine, diacetylmorphine (heroin), tramadol, dihydrocodeine.
Of course every 1's body chemistry is different so not everyone may agree with me but for me myself and I, Oxymorphone is my ultimate opiate euphoria.
But based on my own experience I believe Oxymorphone has the highest binding affinity then any other full or partial agonist opiod.