Oxymorphone extended release in Hydrocodone-experienced patients with chronic low back pain: Subgroup analysis of a 12-week, randomized, double-blind, placebo-controlled study

Patients with chronic pain that does not respond to nonopioid medications may switch to agents combining opioid and nonopioid analgesics. However, there is a therapeutic ceiling with such agents because the safe maximum daily dose is limited by the nonopioid component. For example, hydrocodone/acetaminophen induces abnormal liver enzyme elevations at ³4 g/d acetaminophen. In this study we performed a subgroup analysis of hydrocodone-experienced patients who participated in a clinical trial of oxymorphone extended release (OPANA^® ER) for chronic lower back pain (CLBP). Among the 250 patients with moderate to severe CLBP enrolled in the study, 104 were receiving hydrocodone-based therapy at screening. Of these, 61% (n=63) were successfully converted and titrated (for £1 mo) to a stabilized oxymorphone ER dose (median = 30 mg every 12 h with £2 doses per day rescue medication). Median pain on a 100-mm Visual Analog Scale was reduced from 71 mm at screening to 23 mm following titration. After stabilization, 61 patients (59%) began double-blind treatment with oxymorphone ER (n=32) or placebo (n=29) for up to 12 weeks. Fewer oxymorphone ER patients than placebo patients discontinued treatment owing to lack of efficacy (12% vs 55%). Before titration, a minority (49%) of patients rated their previous hydrocodone-based therapy as Good to Excellent; after titration 99% rated oxymorphone ER Good to Excellent. At final visit, more oxymorphone ER patients than placebo patients rated their medication as Good to Excellent (78% vs 22%; P<0.001). Physician ratings followed a similar pattern and favored oxymorphone ER (P<0.001). Anxiety, bronchitis, and pain exacerbated were the most frequently reported adverse events during double-blind treatment with oxymorphone ER (2 patients each). In this study, the majority of hydrocodone-experienced patients with poorly controlled pain were titrated to an effective and well-tolerated dose of oxymorphone ER.

This research was supported by Endo Pharmaceuticals Inc.