Low-Dose Naltrexone and Acetaminophen Combination in the Treatment of Chronic Low Back Pain (ANODYNE-4)

Inclusion Criteria: 1. The patient is a male or female 18 years of age or older. 2. A clinical diagnosis of nonmalignant, chronic low back pain (CLBP). LBP, as defined by Quebec Task Force in class 1 - pain without radiation and class 2 - pain with proximal radiation above the knee. CLBP is defined as being present for at least several hours a day, at least half the days in the previous 6 months, and being the principal pain condition. (In accordance with the NIH 2013 Task Force on Research Standards for Chronic Low Back Pain). 3. The 24-hour average pain intensity (API) mean score for the baseline period is ≥ 4 and ≤ 8, \[measured on the 11-point (0-10) numeric rating scale (NRS)\] with each individual score ≥ 3. In addition, the Oswestry Disability Index (ODI) score during the Randomization Visit is ≥ 30% and ≤ 60%. 5\. The patient agrees to refrain from taking opiate medications from Visit 1 to 7 days after the last dose of the study drug. 6\. The patient agrees to limit their rescue pain medications to acetaminophen 2000 mg per day for the duration of the study. 7\. The patient is willing and able to discontinue use of non-pharmacological pain management modalities (e.g. TENS, physical therapy, chiropractic manipulations, biofeedback, and acupuncture) for the duration of the study. 8\. The patient has been taking a stable dose of a medication with pain prevention potential for at least 6 weeks prior to the screening visit and agrees to not start, stop, or change the dose of any medication with pain prevention potential during the study period. (E.g., tricyclic antidepressants, anticonvulsants, selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), herbal preparations (e.g. feverfew or St. John's wort)). Botulinum toxin injections and steroid injections to the spine must be discontinued six months prior to Visit 1. 9\. The patient is able to complete study questionnaires, comply with the study requirements and restrictions, and willing to provide written informed consent and authorize HIPAA. 10\. The patient agrees not to undergo any elective surgery, including spine surgery or injections to the spine (e.g. botulinum toxin, steroid, etc.) for the duration of the study. 11\. The Female patient who is premenopausal or postmenopausal less than 1 year, or have not had surgical sterilization (i.e., tubal ligation, partial or complete hysterectomy) must have a negative serum pregnancy test, be non-lactating, and…