Oral prolonged-release oxycodone/naloxone offers equivalent analgesia to intravenous morphine patient-controlled analgesia after total knee replacement. A randomized controlled trial

BACKGROUND: The purpose of this study was to determine whether oral prolonged-release oxycodone-naloxone combination (OXN) could provide equivalent analgesia and a side-effect profile similar to intravenous morphine patient-controlled analgesia (IVPCA) for the control of pain in the immediate postoperative period after total knee replacement (TKR). METHODS: All patients received a sciatic nerve block with 0.3% ropivacaine 15 mL, femoral nerve block with 0.5% ropivacaine 20 mL, spinal anesthesia and postoperative continuous femoral nerve infusion (ropivacaine 0.2% 4 mL/h). After surgery, patients were randomly allocated to receive either 10 +10 +5 mg controlled release OXN oral administration 12 hourly or IVPCA with morphine (2 mg bolus, no basal infusion). The primary outcome was the average rest and dynamic pain for the first 48 h postoperatively. Secondary outcomes were: post operative nausea vomiting (PONV) and the total morphine consumption. RESULTS: OXN group experienced better pain control at rest during the first (0.89 +/- 1.54 vs. 1.27 +/- 1.82, P=0.0019) and second (1.03 +/- 1.69 vs. 1.65 +/- 2.05, P=0.0006) postoperative period. There was no statistically significant difference in pain score during movement between the two groups. The secondary outcome measures showed no significant differences in the total morphine consumption (12.04 +/- 1.1 vs. 11.46 +/- 3.7 mg, P=0.20) or PONV (0.6 +/- 0.8 vs. 0.8 +/- 1.0, P=0.40). CONCLUSIONS: This study show that in the immediate postoperative period after TKR, the patients receiving oral prolonged-release OXN experienced the same to better pain control than those receiving morphine IVPCA, with a similar degree of PONV.