Effects of epidural naloxone on pruritus induced by epidural morphine: a randomized controlled trial

Background: Epidural morphine produces prolonged analgesia but has many side effects including pruritus. Naloxone is an antagonist that can reverse the side effects of morphine. Method: We studied the effects of continuously administered epidural naloxone mixed with morphine on side effects and analgesia in a randomized, double blind, two-armed study. Fifty-eight pregnant women undergoing cesarean section were enrolled. All patients received a 4-mg epidural bolus of morphine in the post-anesthetic care unit. After this, patients in group M (n = 28) received continuous epidural morphine (6 mg over 48 h) in 0.1% bupivacaine; patients in group N (n = 30) received an epidural infusion containing naloxone (1.2 mg over 48 h) and morphine (6 mg over 48 h) in 0.1% bupivacaine. The infusion rate was 2 mL/h. Results: The incidence (82% versus 47%) and severity of pruritus were lower in group N than group M (P = 0.001). There were no significant differences in pain score or in the incidence of nausea, vomiting or urinary disturbance between groups. Conclusion: Continuous epidural infusion of naloxone combined with morphine is effective in reducing the incidence and severity of pruritus induced by epidural morphine. (C) 2004 Elsevier Ltd. All rights reserved.