• Change in pain intensity from baseline (pre-randomization) to last assessment.
  

• Time to early discontinuation due to lack of efficacy
  
• Patient’s Global Assessment of Pain Medication
  
• Physician’s Global Assessment of Pain Medication
  
• Safety as measured by AEs
  

Patients with low back pain who are sub-optimally responsive to their current analgesic treatment begin open-label treatment with oxymorphone extended release (ER). During the Open-Label Titration Period, patients will receive daily oxymorphone ER by mouth (PO) q12h. The investigator will initiate the Open-Label Titration Period using study drug at a dose of 5 mg PO q12h for 2 days; thereafter, patients will continue receiving 5 mg q12h or be titrated at increments of 5-10 mg q12h every 3-7 days until stabilization is achieved. The goal of the Open-Label Titration Period is to determine for each patient a fixed dose of study medication that is tolerated and achieves adequate analgesia. Stabilized patients will be randomiozed to either continue with current dose of oxymorphone ER or receive placebo for a total duration of 12 weeks.

Inclusion Criteria:

• Males or females 18 years of age or older
• opioid naïve
• Have an initial pain intensity score of at least 50 mm VAS
• In good health as determined by the investigator on the basis of medical history and physical examination
• Have moderate to severe chronic non-neuropathic LBP that has been present daily for at least several hours per day for a minimum of three months prior to the Screening
• Any adjunct therapy for back pain such as physical therapy, biofeedback therapy, acupuncture therapy or herbal remedies, based on the patient’s current status should remain unchanged during the period of participation of the patient
• Written informed consent

Exclusion Criteria:

• Pregnant and/or lactating
• Radiculopathy, fibromyalgia, reflex sympathetic dystrophy or causalgia (complex regional pain syndrome), acute spinal cord compression, cauda equina compression, acute nerve root compression, severe lower extremity weakness or numbness, bowel or bladder dysfunction secondary to cauda equina compression, diabetic amyotrophy, meningitis, discitis, or back pain due to secondary infection or tumor
• Cannot or will not agree to stop local regional pain treatments during the study (nerve/plexus blocks or ablation, neurosurgical procedures for pain control, or inhalation analgesia). The patient must not have a nerve/plexus block within 4 weeks of screening
• Intend to alter physical therapy regimen during the study.
• Surgical procedures directed towards the source of back pain within 6 months of screening
• Pain which is secondary to confirmed or suspected neoplasm
• Dysphagia or difficulty swallowing tablets or capsules, or an inability to take oral medication
• Significant prior history of substance abuse or alcohol abuse
• Use of any investigational medication within 30 days prior to the first dose of study medication
• Previous exposure to oxymorphone
• History of clinically significant intolerance to oxymorphone or a known hypersensitivity to opioid analgesics
• History of seizure
• Ileostomy or colostomy
• Use of MAO inhibitor within 14 days prior to the start of study medication
• Other clinically significant conditions as judged by the investigator