I have long term pain from back and neck injuries. I have been taking opana er every since it came out for long term pain control. Last month the doctor had a urine test done which he stated came back negative for opana. This month the same thing happened. I am taking my medicine every day and do not miss doses.

How can this be happening? I am taking the medicine. Are there alternative testes other than urine sample that can prove I am taking this medicine?