Phase 2 Chronic Low Back Pain Study

This phase 2, multicenter, double-blind (DB), placebo-controlled, randomized withdrawal study compared the analgesic efficacy and safety of hydrocodone/acetaminophen extended release to placebo in subjects with moderate to moderately severe chronic lower back pain (CLBP). Participants met pre-defined criteria at the conclusion of the open-label (OL) Titration Period to proceed to randomization into the double-blind (DB) Maintenance Period of the study. Study drug was given for a total of approximately 5 weeks, which included 2 weeks in OL, 2 weeks in DB, and a 3-day taper. During the OL period, all participants took increasing doses of hydrocodone/acetaminophen extended release until they were taking 2 tablets, twice daily. During the DB period, participants in the hydrocodone/acetaminophen extended release group took 1 hydrocodone/acetaminophen extended release tablet twice daily throughout the 2 weeks, while participants in the placebo group took 1 placebo tablet twice daily.