Introduction: In short-term placebo-controlled trials, OPANA^® ER (oxymorphone hydrochloride extended release) has been shown to provide consistent analgesia over a 12-hour period with low peak-to-trough plasma fluctuations.^1,2 In this 12-week randomized, double-blind, placebo-controlled trial, the efficacy of oxymorphone ER was evaluated in opioid-naive patients with moderate to severe chronic low back pain (CLBP).

Methods: Opioid-naive patients were titrated to a stable dose of oxymorphone ER that reduced mean pain intensity to ≤40 mm on a 100-mm Visual Analog Scale (0 = no pain and 100 = worst pain imaginable). Stabilized patients were randomized to continue their stabilized dose of oxymorphone ER or to receive placebo for 12 weeks. Oxymorphone immediate release (5 mg) was available as rescue medication every 4 to 6 hours as needed during the first 4 days following randomization; thereafter, rescue medication was limited to ≤10 mg/d. Pain intensity, patient ratings of satisfaction, and adverse events (AEs) were recorded. All patients provided written informed consent, and protocols were approved by an Institutional Review Board.

Results: The least squares mean change in pain intensity from baseline to final visit was significantly greater for patients on placebo (26.9, n=99) compared with patients maintained on oxymorphone ER (10.0, n=105; P<0.0001). Discontinuations from lack of efficacy were 3-fold higher in the placebo group (35/100 [35%]) compared with the oxymorphone ER group (12/105 [11.4%]), with placebo patients discontinuing significantly sooner than oxymorphone ER patients (P<0.0001). At final visit, significantly more oxymorphone ER patients rated their pain medication as Good to Excellent compared with placebo (82% vs 42%, respectively; P<0.0001). AEs were generally mild to moderate; nausea and diarrhea were the most common AEs.

Conclusions: The majority of opioid-naive patients were successfully titrated to a stable, well-tolerated dose of oxymorphone ER that provided significant relief from CLBP during 12 weeks of double-blind treatment.