Oxymorphone
"I began taking pain meds on a 12 hr basis with prn oxycodone for breakthrough pain in 1996. We started with oxycontin ER, which has actually been the most effective, although very shortly we discovered I am a rapid metabolizer and it had to be increased to every 8 hrs. Then that doc retired. The new one refused to give it to her pts, so I went thru a different pain med about every 3yrs....until I hit the jackpot w Opana! It took minor juggling the 1st 3 months, but for 5yrs I have taken it or the generic & had no side effects & haven't needed a dose increase!
As a retired RN, PhD, I will suggest you ask your doc  do genetic screening focusing on one's body's ability to take specific drugs successfully. "