Efficacy and Safety of Oxymorphone Extended Release in Opioid-Experienced Patients With Chronic Non-Malignant Pain

Inclusion Criteria: * Males or females 18 years of age or older * In good health as determined by the Investigator on the basis of medical history and physical examination. * Moderate to severe chronic non-neuropathic low back pain that has been present daily for at least several hours per day for a minimum of three months prior to the screening. * On a stable around-the-clock opioid pain medication for the management of moderate to severe chronic lower back pain. * Expected to require a total daily oxymorphone ER dose that is a minimum of 20 mg per day (oral morphine equivalent: approximately 60 mg) and will not exceed 220 mg oxymorphone ER (oral morphine requirement: approximately 660 mg). * 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 * Subjects with 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 durin…