OPANA^® ER (oxymorphone extended release) is a new long-acting oral opioid for the treatment of chronic moderate to severe pain. A retrospective analysis was performed to determine whether age, gender, or previous opioid use affect patient responses to individualized doses of OPANA^® ER for the treatment of chronic low back pain (CLBP). Data were combined from 2 randomized controlled trials, with 1 trial each in opioid-naive or opioid-experienced patients. Both studies employed an open-label titration/stabilization period in which adults were titrated to a stabilized dose of OPANA^® ER that reduced pain intensity to ≤40 mm (100-mm Visual Analog Scale [VAS]) on 3 of 5 consecutive days. Stabilized patients were then randomized to double-blind treatment with either their stabilized dose of OPANA^® ER or placebo every 12 hours for 12 weeks. OPANA^® rescue medication was available. Pain intensity and adverse events (AEs) were recorded. Overall, 63% of men (174/278), 59% of women (174/297), 63% of patients ≤65 years (321/495), and 45% of patients >65 years (36/80) successfully completed titration. In addition, the majority of opioid-naive (57%; 143/250) and opioid-experienced (63%; 205/325) patients were successfully titrated, and discontinuations due to AEs were low in both groups (18.1% and 18.7%, respectively). At each assessment during double-blind treatment, OPANA^® ER-treated patients had significantly lower mean VAS scores than patients on placebo (range 21—25 mm vs 31—38 mm, respectively; P<0.001) and efficacy was not affected by age, gender, or previous opioid use (all P≥0.086). More OPANA^® ER patients experienced moderate opioid-related AEs (13.7% vs 4.7% with placebo; P=0.012). In this diverse population of CLBP patients, the majority of patients were titrated to a well-tolerated efficacious dose of OPANA^® ER, and neither age, gender, nor previous opioid use affected the durability of analgesia over 12 weeks of double-blind treatment. Supported by Endo Pharmaceuticals Inc.