2026 Southeastern Residency Conference

Background: Opioid-induced constipation (OIC) is a frequent and challenging side effect of pain management in critically ill patients. While it is standard of care to initiate conventional laxatives concurrently with opioid therapy, they do not directly address the underlying mechanism of OIC. Oral naloxone offers a targeted approach by acting as a mu-opioid receptor antagonist. Due to its low oral absorption, it is thought to primarily exert peripheral effects, helping relieve constipation with minimal impact on central analgesia. Despite its theoretical safety profile, evidence regarding its effects on pain control is not well defined in the available literature. This study aimed to evaluate the effect of oral naloxone on pain scores and opioid requirements in a large, real-world cohort of critically ill patients.

Methods: This multicenter, retrospective pre–post cohort study was conducted across eight community teaching hospitals within AdventHealth Central Florida Division South. Adult patients admitted to an intensive care unit (ICU) who received at least one dose of oral naloxone for OIC and received opioid treatment for at least 24 hours prior to the first dose of oral naloxone were eligible. Patients with chronic opioid use, concurrent peripherally acting mu-opioid receptor antagonists, or chronic naloxone use were excluded. The primary outcome was within-patient change in pain scores 24 hours before and after naloxone initiation, stratified by assessment tool. Secondary outcomes included changes in scheduled and rescue opioid use (morphine milligram equivalents [MME]) and bowel movement occurrence. Continuous outcomes were analyzed using the Wilcoxon signed-rank test and categorical outcomes using the exact McNemar test.

Results: Among 105 patients, fentanyl was the predominant opioid (81%). Pain was most commonly assessed using the Critical Care Pain Observation Tool (CPOT) (77%), followed by the Numeric Rating Scale (NRS) (20%), and Visual Analogue Scale (VAS) (3%). No significant change in pain scores was observed in the CPOT group (median 0.10 vs 0; p = 0.073). NRS scores showed a small but statistically significant decrease (median 2.9 vs 2.5; p = 0.031), while VAS scores did not change significantly (median 2.6 vs 1.8; p = 0.593). Scheduled opioid use decreased significantly (median 555 vs 357.5 MME; p = 0.004), with no change in rescue opioid use (median 5 vs 0 MME; p = 0.831). Bowel movement occurrence increased from 13% to 44% (p <0.001).

Conclusion: In critically ill patients predominantly receiving fentanyl infusions, oral naloxone was not associated with increased pain scores and was associated with increased bowel movement occurrence. These findings suggest that oral naloxone may be a safe adjunct for the management of OIC in ICU patients without compromising analgesia.