Intravenous oxycodone compared to morphine for post-operative opioid-related adverse events in opioid naïve patients: a prospective randomized controlled trial

Abstract Bacground As intravenous oxycodone is as potent as morphine for pain relief, the purpose of this study was to assess opioid-related adverse events (ORAEs) of oxycodone vs morphine (1mg/1mg) in opioid naïve patients after general anesthesia and surgery.Methods Patients schedulled for total hip arthroplasty under general anesthesia were randomized in a 1:1 ratio to receive oxycodone or morphine (titration in PACU followed by intravenous PCA: bolus 1 mL, lockout time 7 min). Primary endpoints was number of patients with ≥1 ORAEs at H24 (at least one of the following complications: nausea, vomiting, respiratory depression, pruritus (itch), urinary retention requiring evacuation, allergy (skin reaction), hallucination (perception without object)). Patients were followed up to 4 months.Results Among 241 patients included in the ITT analysis, there was no difference in patient characteristics. At H24, there were 55 patients with at least one ORAEs in oxycodone group versus 46 in morphine group (48% vs 40%, p=0.19; relative risk RR (oxycodone vs morphine) = 1.22 [0.91; 1.63]). Oxycodone vs Morphine requirements were respectively: 6 [0-11] vs 8 [0-12] mg for titration in PACU (p=0.06) and 15 [8-26] vs 8 [5-16] mg during PCA period at H24 (p=0.001). The total dose of morphine administered within the first 24 h was 22 [12-37] vs 19 [11-28]mg for oxycodone (p=0.048). Pain scores (rest, movement: H0-H48) and neuropathic pain score after 4 months were similar in both groups.Conclusion Even if lower doses of oxycodone were required for PACU titration and over the first 24h, it did not lead to less ORAEs.