Controlled‐release oxycodone compared with controlled‐release morphine in the treatment of cancer pain: A randomized, double‐blind, parallel‐group study

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Abstract
Controlled‐release oral formulations of oxycodone and morphine are both suitable analgesics for moderate to severe pain. They were compared in cancer‐pain patients randomized to double‐blind treatment with controlled‐release oxycodone (n = 48) or controlled‐release morphine (n = 52) every 12 h for up to 12 days. Stable analgesia was achieved by 83% of controlled‐release oxycodone and 81% of controlled‐release morphine patients in 2 days (median). Following titration to stable analgesia, pain intensity (0/none to 3/severe) decreased from baseline within each group (p≤ 0.005), from 1.9 (0.1) to 1.3 (0.1), mean (SE), with controlled‐release oxycodone, and from 1.6 (0.1) to 1.0 (0.1) with controlled‐release morphine (no significant between‐group differences). Typical opioid adverse experiences were reported in both groups. Hallucinations were reported only with controlled‐release morphine (n = 2). Visual analog scores (VAS) for ‘itchy’ and ‘scratching’ were lower with controlled‐release oxycodone (p≤ 0.044), as was peak‐to‐trough fluctuation in steady‐state plasma concentration (p = 0.004). The correlation between plasma concentration and dose was stronger (p = 0.026) for oxycodone (0.7) than morphine (0.3). The relationship between pain intensity (VAS) and plasma concentration was more positive for oxycodone (p = 0.046). There was a positive relationship between morphine‐6‐glucuronide concentrations and urea nitrogen and creatinine levels (p = 0.0001). Controlled‐release oxycodone was as effective as controlled‐release morphine in relieving chronic cancer‐related pain, and as easily titrated to the individual's need for pain control. While adverse experiences were similar, controlled‐release oxycodone was associated with less itching and no hallucinations. Controlled‐release oxycodone provides a rational alternative to controlled‐release morphine for the management of moderate to severe cancer‐related pain.