Introduction: If chronic pain is not effectively treated with nonopioid medications, patients may be initiated on an agent combining opioid and nonopioid analgesics. Patient opioid requirements vary widely, and the daily dose of a combination agent may be limited by the nonopioid component. For example, hydrocodone/acetaminophen induces abnormal liver enzyme elevations at ≥4 g/d acetaminophen.¹

Materials and Methods: Data were summarized for a subset of patients with suboptimal responses to hydrocodone-containing combination therapy who participated in a randomized controlled trial assessing a single-agent opioid, oxymorphone extended release (OPANA^® ER), for chronic lower back pain (CLBP). Patients with moderate to severe CLBP were titrated (for ≤1 month) to a stabilized oxymorphone ER dose (every 12 h) that reduced pain (to ≤40 mm on 100-mm Visual Analog Scale [VAS]) with ≤2 doses/d of rescue medication. Patients were then randomized to double-blind placebo or oxymorphone ER for 12 weeks as described previously.² Informed consent and Institutional Review Board approval were obtained.

Results: 63/104 hydrocodone-experienced patients were successfully titrated to a stable oxymorphone ER dose (median = 60 mg equivalent to approximately 120 mg hydrocodone)³; 61 patients entered double-blind treatment with oxymorphone ER (n=32) or placebo (n=29). Mean VAS declined from 70 mm at screening to 23 mm after titration. During double-blind treatment, mean VAS increased 33.2 mm with placebo vs 7.7 mm with oxymorphone ER (least squares mean difference, –26.1; P=0.001). One patient in each group experienced constipation. Two oxymorphone ER patients and 4 placebo patients discontinued due to adverse events.

Conclusions: The majority of hydrocodone-experienced patients with poorly controlled pain obtained an effective and generally well-tolerated oxymorphone ER dose. Switching from an opioid combination product to the single-agent opioid oxymorphone ER gives patients the ability to achieve adequate pain relief without the dosing limitations imposed by the nonopioid component of a combination product.