Objective: The effects of combined oxycodone/naloxone prolonged release tablets (OXN PR) were investigated in patients with moderate-to-severe chronic cancer-related or non-cancer pain. All patients had opioid-induced constipation (OIC) which persisted despite substantial laxative therapy.
Research design and methods: This pooled analysis included 75 patients with OIC at study entry that was refractory to at least two laxatives with different modes of action. Patients completed randomized, double-blind treatment with OXN PR 20-120 mg/day for either 12 weeks (OXN 9001: non-cancer pain study) or 4 weeks (OXN 2001: cancer-related pain study). Analgesia and bowel function were assessed using the Brief Pain Inventory Short Form and Bowel Function Index (BFI), respectively. Use of laxative medication and safety were assessed throughout the studies.
Clinical trial registration: NCT00513656, EudraCT 2005-002398-57, EudraCT 2005-003510-15.
Results: Statistically and clinically significant improvements in bowel function were observed following double-blind treatment with OXN PR. Mean (SD) reduction in BFI score was 21.2 (28.8) and comparable in patients with cancer-related (19.0 [28.9]) and non-cancer pain (23.3.[29.0]; P ≤ 0.0002). Furthermore, the proportion of patients with a BFI score within normal range (≤28.8) increased from 9.5% at screening to 43.1% at Day 15 of OXN PR. While all patients used ≥2 laxatives of different classes at screening, during study treatment 36% stopped using laxatives (P < 0.001). OXN PR provided effective analgesia, evidenced by stable pain scores during study treatment, and there were no unanticipated adverse events.
Conclusions: OXN PR significantly improved bowel function and reduced the use of laxatives in patients with OIC, previously unresponsive to at least two different classes of laxatives. OXN also provided effective analgesia for patients with moderate-to-severe cancer-related pain and non-cancer-related pain.
Keywords: Chronic pain; Constipation; Laxatives; Naloxone; Opioid analgesic; Oxycodone.