Intranasal Oxymorphone is a bit more powerful than that... look at it this way.
I believe if snorted on a FULL MEAL (preferably) one that’s HIGH IN FAT, the bioavailability would be something like 70-80% with a much different/higher protein binding. Also, it bypasses the blood brain barrier and almost ALL the drug goes to your brain an spine. For Opana this is amazing because the Mu receptors which is what Oxymorphone targets all three times are almost all in the brain and spine... also the Mu receptors are highest for euphoria and very high for pain relief.
http://en.wikipedia.org/wiki/Mu_Opioid_receptor
http://www.drugbank.ca/cgi-bin/getCard.cgi?CARD=APRD00158.txt
According to the drug bank Opana/Oxymorphone primarily binds/interacts with Mu receptors...
The main reason a person would prefer Oxycodone of Oxymorphone is that it interacts with all three receptor groups... spread out. Otherwise it is pure bullshit... snorting Oxymorphone AFTER eating a FULL meal is 7-10 times the euphoria, potency, and duration of any ROA/MOA of Oxycodone.
http://www.drugbank.ca/cgi-bin/getCard.cgi?CARD
B00497
That is why you have to be SUPER careful/responsible with Opana even more so than with most Opiates/Opioids... that is the bottom line.
~BIG~