I'm so sorry you're going through this. It's not uncommon for an insurance company to want people to try other cheaper medications to see if they work. If they don't then they will usually allow you to take what does work.
I've never taken Opana before so I can't give you any advice about it. I do know that we're all different and respond to medications differently. Opana might work very well for you but not work for me, or, the other way around.
I have heard from a few people that Opana is stronger than Morphine. Again, we're all different.
How long does your insurance company want you to stay on this med. If it doesn't help, or is much less stronger than your Morphine call your Dr to let him/her know. They should contact your insurance company to let them know it's not working.
Please keep us up to date on how you're doing. We're always here to help any way we can.