Advantages of intrathecal nalbuphine, compared with intrathecal morphine, after cesarean delivery : An evaluation of postoperative analgesia and adverse effects

We performed a prospective, randomized, double-blinded, multicenter study to compare the analgesic efficacy and adverse effects of intrathecal nalbuphine, at three different doses, and intrathecal morphine for postoperative pain relief after cesarean deliveries. Ninety healthy patients at full term who were scheduled for elective cesarean delivery with spinal anesthesia were enrolled in the study. They received 10 mg of hyperbaric bupivacaine 0.5% with either morphine 0.2 mg (Group 1), nalbuphine 0.2 mg (Group 2), nalbuphine 0. 8 mg (Group 3), or nalbuphine 1.6 mg (Group 4). Only patients in Groups 1 and 2 reported pain during surgery. Postoperative analgesia lasted significantly longer in the morphine group, compared with the nalbuphine groups (P: < 0.0001). In the nalbuphine groups, postoperative analgesia lasted longest with the 0.8-mg dose. The additional increase to 1.6 mg did not increase efficacy. The incidence of pruritus was significantly higher in Group 1 (11 of 22), compared with Group 2 (0 of 22, P: < 0.0002), Group 3 (0 of 23, P: < 0.0001), and Group 4 (3 of 20, P: < 0.02). Postoperative nausea and vomiting were more frequent in Group 1 (5 of 22), compared with Group 2 (0 of 22, P: < 0.05), Group 3 (0 of 23, P: < 0.05), and Group 4 (3 of 23, not significant). There was no maternal or newborn respiratory depression. Neonatal conditions (Apgar scores and umbilical vein and artery blood gas values) were similar for all groups. This study suggests that intrathecal nalbuphine 0.8 mg provides good intraoperative and early postoperative analgesia without side effects. However, only morphine provides long-lasting analgesia. Small doses of intrathecal nalbuphine produce fewer adverse effects, such as pruritus and postoperative nausea and vomiting, compared with intrathecal morphine. This may allow earlier discharge of patients from the recovery room.