Did you ask your doctor any of this?
It's a muscle relaxer which some people do abuse but not an awful lot. I have had back problems for a few years now and muscle relaxers really don't tend to help if you ask me. What seems to work the best is ibuprofen along with heat or cold. If you are in an intensive outpatient program I don't think I would mess with it unless you must. Are you easily addicted to most substances? I would first give the ibuprofen and a heating pad a try first and see what you think.
What kind of back pain do you have? I may be able to offer some other ideas.
Brian