Is it ok to use Demerol along with a fentanyl patch ?

I have SLE (Systemic Lupus Erythematosus) and am currently in the middle of a bad flare-up. I'm usually given 100 mg. Demerol (Intramuscular injection) for joint pain. My rheumatologist recently put me on DUROGESIC fentanyl patch (50 mcg). I'm now on the 2nd day since application of the patch. So far, the pain has not decreased though. My doctor said that some people require additional medication until the fentanyl enters the bloodstream. Is it safe to take Demerol as well with the patch ?