Epidural neostigmine produces analgesia but also sedation in women after cesarean delivery.

BACKGROUND Intrathecal neostigmine produces analgesia but also nausea, limiting its utility. In contrast, epidural administration of neostigmine has been suggested to produce postoperative analgesia without nausea in nonpregnant patients. The purpose of this study was to examine the dose range for efficacy and side effects of epidural neostigmine in women at cesarean delivery receiving combined spinal-epidural anesthesia. METHODS After institutional approval and informed consent, 80 patients for elective cesarean delivery were given combined spinal-epidural anesthesia with 8 mg hyperbaric bupivacaine plus 10 microg fentanyl. Patients were randomized to receive either saline or 75, 150, or 300 microg neostigmine (n = 20 per group) in 10 ml saline after cord clamping. Pain, morphine consumption, and side effects were monitored for 24 h. RESULTS Global pain assessment for the first 24 h was reduced from 5.4 +/- 0.2 in the saline group to 3.0-3.5 +/- 0.3 in the neostigmine groups, dose independently. Correspondingly, global satisfaction with neostigmine was also improved (P < 0.05). Nausea and morphine consumption were similar among groups. Intraoperative shivering and sedation were increased in the 300-microg neostigmine group only (P < 0.05), and postoperative sedation was increased by neostigmine in a dose-independent fashion (P < 0.05). CONCLUSIONS Epidural neostigmine produced modest analgesia in women after cesarean delivery. In contrast with previous reports, which focused primarily on nausea, these data suggest that epidural neostigmine can also produce mild sedation for several hours. These data suggest a limited role for single bolus-administration epidural neostigmine for analgesia after cesarean delivery. They also support future study of epidural neostigmine for obstetric analgesia.