Treatment of intrathecal morphine-induced pruritus following Caesarean section

Abstract

Purpose: To compare both the efficacy and cost of nalbuphine and diphenhydramine in the treatment of intrathecal morphine-induced pruritus following Caesarean section. Methods: Eighty patients, undergoing Caesarean section under spinal anaesthesia, were randomized, in a prospective, double-blind trial, to receive either nalbuphine (Group NAL) or diphenhydramine (Group DIP) for the treatment of SAB morphine-induced pruritus. All patients received an intrathecal injection of 10-12 mg hyperbaric bupivacaine 0.75% and 200 μg preservative free morphine. Postoperative pruritus was assessed, using a visual analogue scale (VAS), for 24 hr. Pruritus treatment was administered upon patient request and by a nurse blinded to the treatment given. Patients who failed to respond to three doses of the study drug were deemed treatment failures. Patient satisfaction was assessed with a questionnaire given 24 to 48 hr after surgery. Direct drug costs were calculated based on the pharmacy provision costa as of April 1996. Results: Eighty patients were enrolled and 45 requested treatment for pruritus. Patients treated with NAL (n = 24) were more likely to achieve a VAS score of zero with treatment (83% vs 43%, P < 0.01), had a higher ΔVAS following treatment (4 ± 2 vs 2 ± 2, P < 0.003), and experienced fewer treatment failures (4% vs 29%, P < 0.04), than those treated with DIP (n = 21). Group NAL patients were also more likely to rate their pruritus treatment as being good to excellent (96% vs 57%, P < 0.004). Direct drug costs were higher for NAL than for DIP ($6.4 ± 3.1 vs $1.7 ± 0.7, respectively, P < 0.0001). Conclusion: Nalbuphine is more effective than diphenhydramine in relieving pruritus caused by intrathecal morphine and the cost differences are small.