The combination of prolonged-release oxycodone and naloxone (PR OXN) better relieves pain and opioid-induced constipation than does prolonged-release oxycodone (PR OXY) alone, according to a team of Belgian researchers.
In their study, 65 patients with laxative-refractory opioid-induced constipation (OIC) were given PR OXY or PR OXN at a median dose of 20 mg/d. They were assessed for pain and constipation relief during 3 visits conducted over 12 weeks.
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Study results showed PR OXN was superior to PR OXY in pain relief, OIC, and quality of life. The Bowel Function Index (BFI) showed a statistically significant and clinically relevant improvement of 48.5 points from visit 1 to visit 3 (P < .001; 95% confidence interval [CI], 44.4-52.7).
The researchers note that a change in the BFI of ≥ 12 points is related to clinically meaningful changes in bowel habits in patients with OIC. The average BFI was < 28.8 after 6 weeks of PR OXN, indicating that most patients were no longer constipated despite opioid treatment.
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The mean pain score was significantly reduced, on average 2.1 units during treatment (P < .001; 95% CI, 1.66-2.54). At 18 weeks, the mean score was 3.8, on a scale of 0 to 10.
The researchers say the median PR OXN dose remained consistent throughout the study. Moreover, the number of patients who used analgesic rescue medication in the 7 days before each visit was reduced from 44 (64.7%) to 26 (41.9%). Therefore, the researchers say, the improved pain relief cannot be explained by an increased dose or increased use of rescue medication and is probably related to the improved constipation relief.
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Quality of life scores increased significantly. Only 2 patients reported an adverse event, both of which were mild or unrelated to the study treatment.
When the study began, the patients were each using at least 2 laxatives with different mechanisms of action. During the study, the number of patients using laxatives in the 7 days before each visit dropped significantly, from 65 to 24 by visit 3. The researchers say, to the best of their knowledge, this is the only noninterventional study of opioid treatment in which laxative use was documented before and during treatment.
The improvement in OIC the researchers observed during PR OXN treatment was not due to laxatives, thus their findings support the rationale that PR OXN treatment counteracts OIC through mechanisms other than those of laxatives and addresses the underlying mechanism of OIC.
Source
Poelaert J, Koopmans-Klein G, Dioh A, et al. Clin Ther. 2015;37(4):784-792.
doi: 10.1016/j.clinthera.2015.02.010.