Well, you're going from 50mg of hydrocodone to 27mg of extended release oxycodone. May be a bit of adjustment only doing twice daily instead of the five times. Difficult to say exactly how much difference you'll feel as far as pain relief, but according to a chart I found here, 30mg of oral hydrocodone is equivalent to 20mg of oxycodone. Just have to give it a shot and see. Did the doctor give a reason for the change?