A Phase 3, Open-Label Period Followed by a Randomized, Double-blind Placebo-controlled Study of the Analgesic Efficacy of Extended-release Hydrocodone/Acetaminophen (Vicodin CR) Compared to Placebo in Subjects With Chronic Low Back Pain

The primary purpose of the study is to test the efficacy of 2 tablets (twice daily) of ABT-712, compared to placebo, administered over a 4-week period in participants with moderate to severe mechanical chronic low back pain (CLBP).