Background and Objectives Epidural morphine is accepted as an efficient means of postoperative pain management. However, development of side effects such as nausea and vomiting and pruritus has been reported. This study compared the efficacy of intravenous infusions of nalbuphine or naloxone in the prevention of epidural morphine-related side effects.

Methods Seventy-five female patients undergoing epidural anesthesia for total hysterectomy were enrolled in a randomized, double-blind study. At the end of the surgery, all patients received epidural 3 mg morphine (every 12 hours) for postoperative pain. Meanwhile, patients in group 1 received an adjuvant intravenous infusion of nalbuphine 60 μg/kg/h, patients in group 2 received intravenous infusion of naloxone 2 μg/kg/h, and patients in group 3 received intravenous saline infusion only. A rescue analgesic of intramuscular 50 mg meperidine (every 4 hours) was available for each patient. Patients were observed for 24 hours.

Results All patients had adequate postoperative pain relief. However, the proportion of patients requiring rescue analgesia and the total consumption of rescue analgesic were higher in group 2 than in the other two groups. The incidence of nausea and vomiting and pruritus was higher in group 3 than in the other two groups.

Conclusions We found that coadministration of either nalbuphine or naloxone with epidural morphine reduces the incidence of morphine-related side effects. However, unlike naloxone, nalbuphine did not attenuate the analgesic effect of epidural morphine.