Phase 2 Chronic Low Back Pain Study

A Phase 2, Randomized Withdrawal Study of the Analgesic Efficacy and Safety of Hydrocodone/Acetaminophen Extended Release Compared to Placebo in Subjects With Chronic Low Back Pain

The primary purpose of this study was to evaluate the analgesic effect and safety of hydrocodone/acetaminophen extended release compared to placebo.

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.

Change From Double-blind Baseline in Chronic Lower Back Pain (CLBP) Intensity by Visual Analog Scale (VAS)

The change from the double-blind randomization baseline (DB baseline: the last assessment before first dose in the double-blind period) to the final assessment in pain intensity, assessed using the CLBP Intensity VAS (0 mm = No Pain and 100 mm = Worst Pain Imaginable). Least squares means and standard errors from an ANCOVA model.

The participant's overall impression of their back pain status was obtained by having the participant answer the question "Considering all the ways your chronic low back pain affects you, how are you doing today?" on a 5-point categorical scale: very good (no symptoms and no limitation of normal activities); good (mild symptoms and no limitation of normal activities); fair (moderate symptoms and limitation of some normal activities); poor (severe symptoms and inability to carry out most normal activities); very poor (very severe symptoms which are intolerable and inability to carry out all normal activities).

The participant's overall impression of the study drug was obtained by having the participant answer the question "How would you rate your overall response to the study medication?" on a 5-point categorical scale: excellent; very good; good; fair; poor.

Inclusion Criteria: Adult subjects who have a diagnosis of chronic low back pain of at least 6 month duration Exclusion Criteria: Subjects with a history of surgical or invasive intervention