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 reported to be effective in treating opioid-induced pruritus. We compared the effectiveness of intramuscular diphenhydramine and nalbuphine for the prevention of epidural morphine-induced pruritus after cesarean section. Methods : One hundred and fifty, American Society of Anesthesiologists physical status I or II, women undergoing cesarean section with epidural anesthesia were randomly assigned to three groups. Group S, group D, and group N received intramuscular 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 the baby. 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. Pruritus occurred less frequently in group N than group D (p = 0.027). At 4 and 12 hrs postoperatively, the pruritus severity was significantly different (p = 0.003 and p = 0.002) and was significantly less in group N than group D in the intergroup comparison (p = 0.013 and p = 0.012). Conclusion : Nalbuphine proved better than diphenhydramine for prevention of epidural morphine-induced pruritus in patients who underwent cesarean section. Prophylactic intramuscular nalbuphine (10 mg) is effective in decreasing the incidence and severity of pruritus and does not affect analgesia.