Considerations for improving assay sensitivity in chronic pain clinical trials: IMMPACT recommendations.

A number of pharmacologic treatments examined in recent randomized clinical trials (RCTs) have failed to show statistically significant superiority to placebo in conditions in which their efficacy had previously been demonstrated. Assuming the validity of previous evidence of efficacy and the comparability of the patients and outcome measures in these studies, such results may be a consequence of limitations in the ability of these RCTs to demonstrate the benefits of efficacious analgesic treatments vs placebo ("assay sensitivity"). Efforts to improve the assay sensitivity of analgesic trials could reduce the rate of falsely negative trials of efficacious medications and improve the efficiency of analgesic drug development. Therefore, an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials consensus meeting was convened in which the assay sensitivity of chronic pain trials was reviewed and discussed. On the basis of this meeting and subsequent discussions, the authors recommend consideration of a number of patient, study design, study site, and outcome measurement factors that have the potential to affect the assay sensitivity of RCTs of chronic pain treatments. Increased attention to and research on methodological aspects of clinical trials and their relationships with assay sensitivity have the potential to provide the foundation for an evidence-based approach to the design of analgesic clinical trials and expedite the identification of analgesic treatments with improved efficacy and safety.

Titration with oxymorphone extended release to achieve effective long-term pain relief and improve tolerability in opioid-naive patients with moderate to severe pain.

OBJECTIVE: Assess the effectiveness and tolerability of a program of gradual dose titration with oxymorphone extended release (ER) for treatment of moderate to severe chronic pain in opioid-naive patients. DESIGN: Open-label, nonrandomized 6-month study with a titration/stabilization period of 50%) reductions of pain interference with quality-of-life measures. There was minimal dose escalation over the 5 months and low use of rescue medication. CONCLUSIONS: Oxymorphone ER provided effective pain relief from moderate to severe chronic pain in opioid-naive patients. Gradual titration was well tolerated, with a low rate of discontinuations caused by AEs.

Efficacy and tolerability of oxymorphone immediate release for acute postoperative pain after abdominal surgery: a randomized, double-blind, active- and placebo-controlled, parallel-group trial.

BACKGROUND: Patients are typically switched from parenteral opioids to oral opioids during the 24 to 48 hours after surgery. In June 2006, an oral immediate-release (IR) tablet formulation of oxymorphone was approved for the treatment of acute moderate to severe pain. Single doses of oxymorphone IR have been reported to provide significant pain relief after orthopedic surgery. OBJECTIVE: This study assessed the efficacy and tolerability of multiple fixed doses of oxymorphone IR in the treatment of acute postoperative pain after abdominal surgery. METHODS: This was a multicenter, randomized, double-blind, active- and placebo-controlled, parallel-group study in men and women aged >or=18 years undergoing abdominal surgery that required a >or=3-cm incision. Patients who discontinued short-acting parenteral opioids and developed moderate or severe pain (4-point categorical scale [none, mild, moderate, or severe] and pain intensity >or=50 mm on a 100-mm visual analog scale [from 0 = no pain to 100 = worst pain imaginable]) within 30 hours after abdominal surgery were randomized to receive oxymorphone IR 10 or 20 mg, oxycodone IR 15 mg, or placebo every 4 to 6 hours after the previous dose. The study included 2 efficacy assessments: a single-dose evaluation for up to 6 hours after the dose, and a multipledose evaluation for up to 48 hours after the first dose. Pain was assessed at 15-minute intervals during the hour after the first dose, hourly thereafter for the next 5 hours, and before each subsequent dose. The primary efficacy end point was the median time to study discontinuation for all causes. Assessment of tolerability was based on the proportion of study discontinuations due to treatment-emergent adverse events (AEs). RESULTS: Three hundred thirty-one patients were included in the study. Demographic characteristics were similar across all groups: 98.8% (327) of patients were women, and 80.1% (265) of the abdominal surgeries were hysterectomies. The mean (SD) age of the study population was 42.6 (9.3) years. The median time to study discontinuation for all causes was significantly longer for all active treatments compared with placebo (oxymorphone IR 10 mg, 17.9 hours; oxymorphone IR 20 mg, 20.3 hours; oxycodone IR 15 mg, 24.1 hours; placebo, 4.8 hours; P < 0.006). Oxymorphone IR 20 mg was significantly more effective than placebo over the 6-hour single-dose evaluation (P < 0.05). With multiple dosing, all active-treatment groups had significantly lower least squares mean current and average pain intensities compared with placebo (P < 0.004 and P < 0.005, respectively). The least squares means of the average pain intensity were significantly lower among patients treated with oxymorphone IR 10 mg, oxymorphone IR 20 mg, or oxycodone IR 15 mg compared with those who received placebo (39.7, 35.2, 39.8, and 50.1, respectively; P < 0.005). Discontinuations due to treatment-emergent AEs did not differ significantly between groups: 8.5% (7/82), 17.3% (14/81), 13.3% (11/83), and 12.9% (11/85) in the oxymorphone IR 10-mg, oxymorphone IR 20-mg, oxycodone IR 15-mg, and placebo groups, respectively. The proportions of patients reporting at least 1 treatment-emergent AE were 46.3% (38/82), 51.9% (42/81), and 54.2% (45/83) in the oxymorphone IR 10-mg, oxymorphone IR 20-mg, and oxycodone IR 15-mg groups, respectively, compared with 34.1% (29/85) in the placebo group (P = NS). The fixed-dose design was a study limitation, as it did not allow titration to effect and thus did not mirror clinical practice. CONCLUSION: In this predominantly female population undergoing abdominal surgery, oxymorphone IR given every 4 to 6 hours for up to 48 hours provided efficacious and tolerable analgesia for moderate to severe pain.

A 12-week, randomized, placebo-controlled trial assessing the safety and efficacy of oxymorphone extended release for opioid-naive patients with chronic low back pain.

OBJECTIVE: Determine the efficacy and tolerability of oxymorphone extended release (OPANA ER) in opioid-naive patients with moderate to severe chronic low back pain (CLBP). DESIGN AND METHODS: Patients > or = 18 years of age were titrated with oxymorphone ER (5- to 10-mg increments every 12 h, every 3-7 days) to a well-tolerated, stabilized dose. Patients were then randomized to continue their oxymorphone ER dose or receive placebo every 12 h for 12 weeks. Oxymorphone immediate release was available every 4-6 h, as needed, for the first 4 days and twice daily thereafter. RESULTS: Sixty-three percent of patients (205/325) were titrated to a stabilized dose of oxymorphone ER, most (203/205) within 1 month. During titration, 18% discontinued from adverse events (AEs) and 1% from lack of efficacy. For patients completing titration, average pain intensity decreased from 69.4 mm at screening to 22.7 mm (p < 0.0001). After randomization, 68% of oxymorphone ER and 47% of placebo patients completed 12 weeks of double-blind treatment. Approximately 8% of patients in each group discontinued because of AEs. Placebo patients discontinued significantly sooner from lack of efficacy than those receiving oxymorphone ER (p < 0.0001). Pain intensity increased significantly more in the placebo group (least squares [LS] mean change 26.9 +/- 2.4 [median 28.0]) than in the oxymorphone ER group (LS mean change 10.0 +/- 2.4 [median 2.0]; p < 0.0001). Oxymorphone ER was generally well tolerated without unexpected AEs. Although limitations of a randomized withdrawal study include the potential for unblinding and opioid withdrawal in placebo patients, opioid withdrawal was limited to two patients in the placebo group and one in the oxymorphone ER group. CONCLUSIONS: Stabilized doses of oxymorphone ER were generally safe and effective over a 12-week double-blind treatment period in opioid-naive patients with CLBP.