Benlysta / Oxymorphone False Negative Test

KD Says:

I have been taking Opana ER (oxymorphone 20mg ER) for several months along with Norco. The first urine test showed both drugs in my results. I started getting a Benlysta infusion monthly since December. Now my urine results show that I'm not taking the Opana ER, which I take religiously! Is there anyway the Benlysta could cause this?