I have morphine in mine right now. I went to the Dr. today and they explained that it could be months until I am at the exact dose that I need, and they may end up changing the medicine used. So like other posters have said- it's an ongoing assessment based on the individual. All I know is that I would have never been able to sit here comfortably on the computer without a large amount of narcotics so this thing must be working! I am not pain free yet but hopefully I'll get there with time.
Good luck!