In the past few years I have been on opiates almost every day, both legally and otherwise, and have taken just about anything and everything and I have noticed that I get -very- irritable on Opana espically. Also it seems that whenever 'a friend of mine' gets Opana for his friends they also get extremely irritable as well. Also whenever they want to get more Opana they turn from asking to demanding.
I have found that this is different than heroin...heroin addicts that are waiting to get their fix are usually just impatient, not 'angry'. They will call you 40 times in 10 minutes while you're trying to talk to your dude but they won't really be angry persay.
However when the people I know are waiting for Opana they get fucking MAD. I have seen people break things, punch walls, and even hit their signifigant others all because of Opana. I am not sure what exactly causes this but I would like to know.