A Study to Compare Oxycodone/Naloxone Prolonged Release Against Codeine/Paracetamol in the Treatment of Moderate to Severe Chronic Low Back Pain or Pain Due to Osteoarthritis

Inclusion Criteria: 1. Male or female subjects at least 18 years or older. 2. Female subjects less than one year post-menopausal must have a negative urine pregnancy test recorded prior to the first dose of study medication, be non-lactating, and willing to use adequate and reliable contraception throughout the study. A highly effective method of birth control is defined as those which result in a low failure rate (i.e. less than 1% per year) when used consistently and correctly such as sterilization, implants, injectables, combined oral contraceptives, some IUDs, sexual abstinence or vasectomised partner. 3. Subjects with a clinical diagnosis of degenerative or primary OA whose primary pain site is of the hip(s) and/or knee(s) and that require around-the-clock opioid therapy in which the diagnosis may be supported by evidence such as one of the following: MRI, CAT, arthroscopy or x-ray. The clinical imaging of OA may include one or more of the following features: joint space narrowing, degenerative changes, osteophyte formation or subchondral cysts. Subjects will identify the most painful joint (hip or knee) for documentation of OA. Pain measurement will be done at this joint only. 4. Subjects with moderate to severe chronic low back pain e.g osteoarthritis, spinal stenosis, spondylolisthesis, failed back surgery, scoliosis, discogenic disorders such as herniated disc. 5. Subjects who are currently receiving codeine/paracetamol combination tablets up to a maximum dose of 120 mg codeine per day or tramadol up to a maximum dose of 100 mg/day or dihydrocodeine / paracetamol tablets up to a maximum dose of 120 mg dihydrocodeine per day. 6. Subjects willing and able to participate in all aspects of the core study, including use of oral medication, completion of subjective evaluations, attending scheduled clinic visits, completing telephone contacts, and compliance with protocol requirements as evidenced by providing written, informed consent. 7. Subjects in which the pre-study, non-opioid analgesics, and all other concomitant medications, including those medications for the treatment of depression are anticipated to remain stable throughout the treatment phase of the study. Exclusion Criteria: 1. Any history of hypersensitivity to oxycodone, naloxone, codeine, ibuprofen, bisacodyl or related products and ingredients. 2. Any contraindication to oxycodone, naloxone, codeine, paracetamol or ibuprofen. 3. Subjects with evidence of significant structural abnormalit…