Post-operative opioid-related adverse events with intravenous oxycodone compared to morphine: A randomized controlled trial

Background: The value of intravenous oxycodone compared to morphine remains controversial. The purpose of this trial was to compare opioid-related adverse events (ORAES) of intravenous oxycodone and morphine after total hip arthroplasty.

Methods: Patients scheduled for total hip arthroplasty were enrolled in this study of post-operative pain treatment with intravenous oxycodone or intravenous morphine (ratio 1:1). After surgery, patients received similar drug regimens for titration in the post-operative care unit followed by intravenous patient-controlled analgesia (PCA). The primary outcome was the number of patients with ≥1 ORAEs within the first 24 hours defined as either nausea, vomiting, respiratory depression, pruritus, urinary retention requiring evacuation, allergy, hallucinations. Secondary outcomes included pain scores and opioid consumption.

Results: The analysis included 238 patients with similar characteristics. There were 55 patients with at least one ORAEs in the oxycodone group vs 46 in the morphine group: 48% vs 40%, P = .19; relative risk = 1.22 (0.91:1.63). Intravenous oxycodone vs intravenous morphine requirements were respectively (median, IQR): 6 (0-11) vs 8 (0-12) mg (P = .06) for titration, 15 (8-26) vs 8 (5-16) mg (P = .001) for PCA, and 22 (12-37) mg vs 19 (11-28) mg for cumulated intravenous consumption (P = .048). During the first 24 hours, there was no difference in secondary outcomes (oxycodone vs morphine, respectively, in %): nausea (15 vs 13), vomiting (5 vs 5), urinary retention (20 vs 12) or pain scores.

Conclusion: This study demonstrates that IV oxycodone did not significantly reduce ORAEs within the first 24 hours compared to similar ratio of IV morphine.