Ondansetron and tropisetron do not prevent intraspinal morphine‐ and fentanyl‐induced pruritus in elective cesarean delivery

Abstract

Although intraspinal morphine has been shown to be effective in providing analgesia after cesarean delivery, pruritus as a side-effect remains a common cause of dissatisfaction. The role of ondansetron has been studied in preventing pruritus but the results have been contradictory. We randomized 98 parturients undergoing elective cesarean section using combined spinal-epidural anesthesia into a double-blinded trial to receive tropisetron 5 mg (T group) or ondansetron 8 mg (O group) or placebo (NaCl group) after delivery, when intrathecal morphine 160 microg and fentanyl 15 microg were used for post-operative pain control. The patients additionally received ketoprofen 300 mg per day. Post-operative itching, nausea and vomiting, sedation and need for rescue analgesics were registered every 3 h up to 24 h, and all patients were interviewed on the first post-operative day. Seventy-six percent of the parturients in the placebo group, 87% in the ondansetron, and 79% in the tropisetron group had itching. The incidence of post-operative nausea and vomiting was 21%, 20% and 11% of the patients in the placebo, ondansetron and tropisetron groups, respectively. Medication for pruritus was needed by 31%, 23% and 39% of the patients in the placebo, ondansetron and tropisetron groups, respectively. In the post-operative questionnaire, the patients reported less post-operative nausea in the tropisetron group than in the placebo group (P < 0.01). Neither ondansetron nor tropisetron prevent itching caused by intrathecal morphine with fentanyl. However, tropisetron reduced post-operative nausea.