title: Comparison of the antinociceptive effect of systemic versus intrathecal magnesium sulphate on spinal morphine analgesia.
abstract: The aim of this work was to compare the possible antinociceptive effect of the intravenous (IV) versus the intrathecal (IT) administration of magnesium sulphate prior to spinal morphine analgesia. This research was conducted in two sets: First; experimentally, to compare the antinociceptive effect of IT magnesium sulphate (375 μg/rat) versus IP magnesium sulphate 100 mg/kg), prior to IT morphine (10 μg/rat). Pain was assessed using Randall-Selitto testing, the hot-plate, and formalin tests. A non-significant difference in the nociceptive threshold was observed between IT and IP magnesium sulphate administration prior to IT morphine in rats. Second: clinically, in patients undergoing orthopedic surgery, who received either an IT mixture of 1 mg of morphine with 3 mL hyperbaric 0.5% bupivacaine, an IT mixture of morphine with bupivacaine and 50 mg of magnesium sulphate, or an IT mixture of morphine bupivacaine plus IV 20 mg/kg of magnesium sulphate as a loading dose over 15 min prior to surgery, followed by infusion at a rate of 10 mg/kg/h. Pain was evaluated using a visual analog pain scale (VAS) score at one hour, 6 h and 12 h postoperatively. The use of IT or IV magnesium sulphate, in addition to the spinal morphine caused a significant decrease in the VAS score in the 6(th) and 12(th) post-operative hours with a non-significant difference between both routes. In conclusion the efficacy of systemic magnesium sulphate to potentiate the analgesic effect of intrathecal morphine is a promising and attractive route of choice for postoperative pain relief during spinal anesthesia. Opioid analgesia could be prolonged and the incidence of motor paralysis, common with the intrathecal route of magnesium sulphate administration, reduced.
authors.affiliation: Anesthesia and surgical intensive care.
authors.forename: Medhat M
authors.initials: MM
authors.lastname: Messeha
authors.affiliation: Clinical Pharmacology Faculty of Medicine, Mansoura University, 35516, Mansoura, Egypt.
authors.forename: Vivian
authors.initials: V
authors.lastname: Boshra
mesh_terms: D000328:Adult; D000700:Analgesics / Q000008:administration & dosage* / Q000494:pharmacology*; D000775:Anesthesia, Spinal; D000818:Animals; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007278:Injections, Spinal; D008278:Magnesium Sulfate / Q000008:administration & dosage* / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D010146:Pain / Q000188:drug therapy*; D010147:Pain Measurement; D011446:Prospective Studies; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000700:Analgesics; D008278:Magnesium Sulfate; D009020:Morphine
keywords: magnesium sulphate; morphine; pain score; spinal anesthesia