Efficacy of Intramuscular Nalbuphine versus Diphenhydramine for the Prevention of Epidural Morphine-induced Pruritus after Cesarean Delivery

Background: Pruritus is the most common side effect of epidural morphine analgesia.Diphenhydramine is a widely used agent for the treatment of urticarial pruritus.Nalbuphine is a mixed opioid agonist–antagonist and has been reportedto be effective in treating opioid-induced pruritus. We compared the effectivenessof intramuscular diphenhydramine and nalbuphine for the preventionof epidural morphine-induced pruritus after cesarean section.Methods: One hundred and fifty, American Society of Anesthesiologists physical statusI or II, women undergoing cesarean section with epidural anesthesia wererandomly assigned to three groups. Group S, group D, and group N receivedintramuscular normal saline (1 ml; n = 50), diphenhydramine (30 mg/1 ml; n= 50), and nalbuphine (10 mg/1 ml; n = 50), respectively, after delivery of thebaby. The occurrence and the severity of pruritus were assessed at 1, 4, 12,and 24 hours after surgery.Results: The overall incidence of pruritus during the 24 hr follow-up period was 72%,68%, and 44% for group S, group D, and group N, respectively. Pruritusoccurred less frequently in group N than group D (p = 0.027). At 4 and 12hrs postoperatively, the pruritus severity was significantly different (p =0.003 and p = 0.002) and was significantly less in group N than group D inthe intergroup comparison (p = 0.013 and p = 0.012).Conclusion: Nalbuphine proved better than diphenhydramine for prevention of epiduralmorphine-induced pruritus in patients who underwent cesarean section.Prophylactic intramuscular nalbuphine (10 mg) is effective in decreasing theincidence and severity of pruritus and does not affect analgesia.