Hi Marb,
Well everyone is different, but thats not a HUGE dose. I would be surprised if it was still very effective after 2 years, but I think you can safely say one could expect some loose bowels, restless legs, achy feelings, possibly with depression and lack of appetite for a few days.
I think a week at most and they would be back on track for the most part, especially if there are no underlying pain reasons to still be on the med.
And there is no way of knowing to what degree the person is phycologically addicted, the first stuff is just your body reacting to a physical dependence,
addiction is much harder to overcome, it will make every part of withdrawal harder and most likey last longer.
May I ask why you were taking it, and for what reason you are quitting? That would help people give you a better idea, but still, everyone will react differently. Can you taper off by say one pill less each few days, then stop from one pill? that will make the physical part of withdrawal negligable.
Good luck, I'm sure others will have more advice for you, some more info from you on what your pain issues have been/are will help too.
Your Friend, Fabby