Background and Goal of Study: Pruritus is the most common side effect of intrathecal morphine for postoperative pain relief. Activation of central 5-hydroxytryptamine subtype 3 (5-HT3) receptors is one of its possible mechanisms.1 Consequently, specific 5-HT3 receptor antagonists could be an effective prophylactic treatment of neuraxial opioid-induced pruritus. Palonosetron is a new potent 5-hydroxytryptamine 3 antagonist. It was reported that palonosetron is more effective than ondansetron for prevention of postoperative nausea and vomiting.2
In a prospective, randomized, double-blind, placebo-controlled study, we evaluated the efficacy of prophylactic administration of ondansetron and palonosetron for the prevention of intrathecal morphine-induced pruritus.
Materials and Methods: The patients were randomized into 3 groups to receive either 8 mg ondansetron IV (group O, n=35), 0.075 mg palonosetron IV (group A, n=35) or normal saline (group P, n=35) 15 min before administration of spinal anesthesia with 8 to 12.5 mg of 0.5% hyperbaric bupivacaine and 0.25 mg of morphine for urologic surgery. Patients were evaluated for incidence and severity of pruritus at 15 min. 30 min, 1, 2, 4, 8, and 24 h after intrathecal morphine administration.
Results and Discussion: The incidence and severity of pruritus was significantly less frequent in the ondansetron and palonosetron groups compared with placebo (52.3%, 47.8%%, and 89.1% respectively, P< 0.01).
Conclusion(s): We conclude that the prophylactic use of ondansetron and palonosetron helps to reduce the incidence and severity of intrathecal morphine-induced pruritus.
1. Szarvas S, Harmon D, Murphy D. Neuraxial. opioid-induced pruritus: a review. J Clin Anesth 2003;15:234 -9.
2. Moon YE, Joo J, Kim JE, Lee Y. Antiemetic effect of ondansetron and palonosetron in thyroidectomy: a prospective, randomized, double blind study. Br J Anaesth 2012; 108: 417-22.