Ultra-low dose of intratecal naloxone to minimize morphine - induced adverse effects

Abstract

Background Intrathecal morphine is not devoid of adverse effects such as nausea, vomiting, and pruritus. Our goal was to study the efficacy of intrathecal ultra-low-dose naloxone in decreasing postoperative morphine-induced adverse effects. Patients and methods A prospective randomized double-blind controlled clinical trial was conducted that involved 100 adult patients undergoing minor anal surgeries under spinal anesthesia. Patients were equally randomized into two groups: group B received 5 mg of 0.5% hyperbaric bupivacaine with 0.2 mg morphine and normal saline as placebo in 2-ml volume, and group L received the same dose of bupivacaine with 0.2 mg morphine, and 5 ng/kg naloxone in the same volume. Postoperative nausea and vomiting (PONV) incidence was assessed during the first postoperative day. Both PONV and itching severity through visual analog scale for each were assessed every 2 h along the first postoperative day. Results There were significant differences between groups regarding the incidence of PONV (P = 0.031). Scales of PONV were significantly higher in group B in the early 10 postoperative hours, and at the 16th-hour score. Pruritus scale was significantly higher in group B than group L at the second and fourth postoperative hours. Conclusion The use of 5 ng/kg intrathecal naloxone along with morphine can reduce the incidence and severity of postoperative intrathecal morphine-induced nausea, vomiting, and itching.