Intravenous butorphanol administration reduces intrathecal morphine-induced pruritus after cesarean delivery: a randomized, double-blind, placebo-controlled study

Abstract

Pruritus associated with intrathecal opioid administration is a common side effect. There is evidence that κ-opioid receptor agonists have antipruritic activity. Butorphanol has agonist actions at both κ-opioid and μ-opioid receptors. This study was designed to evaluate the antipruritic efficacy of butorphanol after intrathecal morphine administration in the setting of a randomized, double-blind study of parturients undergoing cesarean section. Ninety-one women who received combined spinal-epidural anesthesia with 1.2 ml 0.5 % isobaric bupivacaine and 0.1 mg preservative-free morphine were included in this study. After delivery of the baby, the parturients were randomly allocated to two groups: butorphanol group (n = 46) and physiological saline group (n = 45). In the butorphanol group, parturients received an intravenous loading dose of 1 mg butorphanol followed by infusion of 0.2 mg/h butorphanol. The physiological saline group received an infusion of the same volume of physiological saline. The presence of pruritus, visual analog scores for pain, sedation scores, and adverse effects were recorded 1, 2, 4, 6, 8, 10, 12, and 24 h after intrathecal morphine administration. The incidence of pruritus at 24 h was significantly more frequent in the physiological saline group than in the butorphanol group (48.9 vs. 13.0 %, P < 0.001). The severity of pruritus was significantly greater in the saline group than in the butorphanol group 2, 4, 6, 8 and 10 h after intrathecal morphine injection (P = 0.004, 0.001, 0.002, and 0.003, respectively). The visual analog scale scores at 24 h were significantly lower in the butorphanol group than in physiological saline group (P < 0.001). The Ramsay sedation score in the butorphanol group was significantly higher than that in the physiological saline group after 1, 2, 4, 6, 8, 10, 12, and 24 h (P < 0.05). There were no significant differences between the two groups in nausea/vomiting and other adverse effects. Administration of intravenous butorphanol after delivery of the baby can reduce pruritus that has been induced by intrathecal morphine administration in cesarean delivery with combined spinal-epidural anesthesia.