Korean J Pain.  2009 Apr;22(1):58-64. 10.3344/kjp.2009.22.1.58.

Magnesium Sulfate Attenuate Opioid Tolerance in Patients undergoing Major Abdominal Surgery

• Jang MS
• Son Y
• Lee C
• Lee JH
• Park JH
• Lee MJ

• KMID: 1767818
• DOI: http://doi.org/10.3344/kjp.2009.22.1.58

Abstract

BACKGROUND: Magnesium is a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor. Magnesium is thought to be involved in opioid tolerance by way of inhibiting calcium entry into cells.
METHODS
The patients were randomly assigned to three groups according to the anesthetic regimens: Group M received magnesium sulfate and Group C received saline intravenously under remifentanil-based anesthesia. Group S received saline intravenously under sevoflurane based anesthesia in place of remifentanil. The patients in the group M received 25% magnesium sulfate 50 mg/kg in 100 ml of saline, and those patients in groups C and S received an equal volume of saline before induction of anesthesia; this was followed by 10 mg/kg/h infusion of either magnesium sulfate (group M) or an equal volume of saline (groups C and S) until the end of surgery. Pain was assessed on a visual analog scale at 1, 6, 12, 24, and 36 hours after the operation. The time to the first postoperative analgesic requirement and the cumulative analgesic consumption were evaluated in the three groups.
RESULTS
The visual analog scales for pain and the cumulative analgesic consumption were significantly greater in group C than in other groups. The time to first postoperative analgesic requirement was significantly shorter in group C than that in the other groups. There were no differences between group M and S for side effects.
CONCLUSIONS
A relatively high dose and continuous remifentanil infusion is associated with clinically relevant evidence of acute opioid tolerance. NMDA-receptor antagonist, magnesium sulfate as an adjuvant analgesic prevents opioid tolerance in patients who are undergoing major abdominal surgery under high dose and continuous remifentanil infusion-based anesthesia.

Keyword

magnesium sulfate; NMDA receptor; opioid tolerance; remifentanil

MeSH Terms

Anesthesia
Calcium
Humans
Hypogonadism
Magnesium
Magnesium Sulfate
Methyl Ethers
Mitochondrial Diseases
N-Methylaspartate
Ophthalmoplegia
Piperidines
Weights and Measures
Calcium
Hypogonadism
Magnesium
Magnesium Sulfate
Methyl Ethers
Mitochondrial Diseases
N-Methylaspartate
Ophthalmoplegia
Piperidines