A randomised controlled trial with prolonged-release oral oxycodone and naloxone to prevent and reverse opioid-induced constipation.

BACKGROUND: Opioid-induced constipation can have a major negative impact on patients' quality of life. This randomised, double-blinded study evaluated the analgesic efficacy of prolonged-release (PR) oral oxycodone when co-administered with PR oral naloxone, and its impact on opioid-induced constipation in patients with severe chronic pain. Another objective was to identify the optimal dose ratio of oxycodone and naloxone. METHODS: A total of 202 patients with chronic pain (mainly non-cancer related, 2.5% of patients had cancer-related pain) under stable oral oxycodone therapy (40, 60 or 80 mg/day) were randomised to receive 10, 20, 40 mg/day naloxone or placebo. After a 4-week maintenance phase, patients received oxycodone only for 2 weeks. Pain intensity was evaluated using a numerical analogue scale and bowel function was assessed using the bowel function index. RESULTS: No loss of analgesic efficacy with naloxone was observed. Mean pain intensity scores on randomisation were comparable for placebo, 10mg, 20mg and 40 mg naloxone dose, and remained unchanged during treatment. Bowel function improved with increasing naloxone dose. Naloxone 20mg and 40 mg significantly improved bowel function at the end of the maintenance phase compared with placebo (p<0.05). Overall, the combination was well tolerated, with no unexpected adverse events. There was a trend towards an increased incidence of diarrhoea with higher doses of naloxone. The 2:1 oxycodone/naloxone ratio was identified as the most suitable for further development. CONCLUSION: Co-administration of PR oral naloxone and PR oral oxycodone is associated with a significant improvement in bowel function compared with PR oral oxycodone alone, with no reduction in the analgesic efficacy of oxycodone.

Analgesic efficacy and safety of oxycodone in combination with naloxone as prolonged release tablets in patients with moderate to severe chronic pain.

UNLABELLED: This randomized, double-blind, placebo- and active-controlled, parallel-group study was designed to demonstrate the superiority of oxycodone in combination with naloxone in a prolonged release (PR) formulation over placebo with respect to analgesic efficacy. The active control group was included for sensitivity and safety analyses, and furthermore to compare the analgesic efficacy and bowel function of oxycodone PR/naloxone PR with oxycodone PR alone. The analgesic efficacy was measured as the time from the initial dose of study medication to multiple pain events (ie, inadequate analgesia) in patients with moderate to severe chronic low back pain. The full analysis population consisted of 463 patients. The times to recurrent pain events were significantly longer in the oxycodone PR/naloxone PR group compared with placebo (P < .0001-.0003); oxycodone PR/naloxone PR reduced the risk of pain events by 42% (P < .0001; full analysis population). The appearance of pain events was comparable for oxycodone PR/naloxone PR versus oxycodone PR, confirming that the addition of naloxone PR to oxycodone PR in a combination tablet did not negatively affect analgesic efficacy of the opioid. Furthermore, oxycodone PR/naloxone PR offers benefits in terms of an improvement in bowel function. In a therapeutic area of great unmet need, therefore, the combination tablet of oxycodone PR/naloxone PR offers patients effective analgesia while improving opioid-induced bowel dysfunction. Taken together with the observation that the safety profile of oxycodone PR/naloxone PR is consistent with that expected from other opioid analgesics except opioid-induced constipation, these findings indicate that the addition of naloxone to oxycodone in a PR combination tablet offers improved tolerability. Oxycodone PR/naloxone PR is therefore a promising new treatment approach for the management of chronic pain. PERSPECTIVE: This study evaluated the analgesic efficacy and safety of the combination of oxycodone PR/naloxone PR in chronic nonmalignant pain. Opioids are often reduced in dosage or even discontinued as a result of impaired bowel function, leading to insufficient pain treatment. Not only does oxycodone PR/naloxone PR demonstrate analgesic efficacy comparable with oxycodone PR, but it also improves opioid-induced bowel dysfunction, and may therefore improve the acceptability of long-term opioid treatment for chronic pain.