Efficacy and Safety of Hydrocodone Bitartrate Extended-Release Tablets for Moderate to Severe Chronic Low Back Pain

The primary objective of this study is to evaluate the efficacy of hydrocodone bitartrate extended-release tablets at doses of 30 to 90 mg every 12 hours compared with placebo in alleviating moderate to severe pain in patients with chronic low back pain. Patients may be opioid-naïve or opioid-experienced.

The study consisted of a screening period of approximately 7 to 14 days, an open label titration period of up to 6 weeks, and a double blind treatment period of 12 weeks.

The objective of the open label titration period was to find the successful dose of hydrocodone extended release (ER) tablets that produced stable pain relief without unacceptable adverse events (AEs). Stable pain relief was defined as an average pain intensity (API) score over the previous 24 hours of 4 or less and a worst pain intensity (WPI) score of 6 or less on the 11-point numerical rating scale (NRS-11) (0=no pain to 10=worst pain imaginable) for either 4 consecutive days or 4 out of 7 consecutive days, while the same dose of study drug was maintained for up to 7 days. Scores for WPI and API were recorded daily in individual patient electronic diaries. Patients returned to the study center prior to each dose adjustment.

The starting dose of hydrocodone ER tablets depended on whether the subject was opioid-naïve or opioid-experienced. Opioid-naïve participants started at a 15-mg dose of hydrocodone ER tablets every 12 hours. For opioid-experienced participants, the starting dose of hydrocodone ER tablets was to be approximately equivalent to 50% of the dose of opioid analgesic that they were receiving at screening and administered every 12 hours. Investigators switched participants from previous opioid therapy to hydrocodone ER tablets on the basis of predefined dose equivalents.

Participants who met the criterion of a stabilized dose were randomly assigned into the 12 week, double-blind, placebo controlled treatment period on the final day of the open label titration period (baseline visit). Participants began treatment with double blind study drug at the effective dose of hydrocodone ER tablets achieved during the titration period or matching placebo. Rescue medication was permitted in addition to the study drug during the double blind treatment period.

Participants who participated in the study in compliance with the protocol and complete 12 weeks of double-blind treatment with study drug, were considered to have completed the study and could have been eligible to enroll in a 6-month open-label study (study C32337/3104, NCT01922739).

Eligibility Criteria:
Inclusion Criteria:

* The patient has had moderate to severe chronic low back pain for at least 3 months duration before screening.
* The patient is able to speak English and is willing to provide written informed consent, including a written opioid agreement, to participate in this study.
* The patient is willing and able to successfully self-administer the study drug, comply with study restrictions, complete the electronic diary, and return to the study center for scheduled study visits, as specified in the protocol.
* The patient is 18 through 80 years of age at the time of screening.
* Women of childbearing potential (not surgically sterile or 2 years postmenopausal) must use a medically accepted method of contraception, agree to continue use of this method for the duration of the study and for 30 days after participation in the study, and have a negative pregnancy test at screening. - Acceptable methods of contraception include barrier method with spermicide, intrauterine device (IUD), or steroidal contraceptive (oral, transdermal, implanted, and injected) in conjunction with a barrier method. NOTE: A woman will be considered surgically sterile if she has had a tubal ligation, hysterectomy, bilateral salpingo-oophorectomy or bilateral oophorectomy, or hysterectomy with bilateral salpingo-oophorectomy.
* Other criteria apply.

Exclusion Criteria:

* The patient is taking a total of more than 135 mg/day of oxycodone, or equivalent, during the 14 days before screening.
* The patient's primary painful condition under study is related to any source of chronic pain other than low back pain.
* The patient has radicular (nerve compression) pain or another type of purely neuropathic pain.
* The patient has known or suspected hypersensitivities, allergies, or other contraindications to any ingredient in the study drug.
* The patient has a recent history (within 5 years) or current evidence of alcohol or other substance abuse, with the exception of nicotine.
* The patient has medical or psychiatric disease that, in the opinion of the investigator, would compromise collected data.
* Other criteria apply.