| The Potentiation of the Analgesic Effect of Intrathecally Coadministered Magnesium Sulphate and Bupivacaine in Duration of Sensory Blockade in Rats. |
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Jae Chan Choi, Kyung Bong Yoon, Jin Soo Kim, Soon Yul Kim, Kwang Ho Lee, Young Bok Lee, Hyun Kyo Lim, Eun Sung Jun |
1Department of Anesthesiology, Yonsei University Wonju College of Medicine, Korea. hklim@wonju.yonsei.ac.kr
2Department of Anesthesiology, Ajou University School of Medicine, Suwon, Korea. |
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| Abstract |
BACKGROUND
Based on previously reported articles, magnesium sulphate seemed to cause a motor paralysis, but not complete analgesia when administered intrathecally alone, but is likely to have a partial analgesic effect. Accordingly, we tested a hypothesis that magnesium sulphate might potentiate the analgesic effect when coadministered intrathecally with bupivacaine.
METHODS
Eighteen male Sprague-Dawley rats were allocated into three groups of six animals each. The duration of sensory blockade was determined by observing the period when the animal did not vocalize and/or withdraw (struggle) while forceps-pinch tests were applied to a hindlimb paw. The six animals in each of the following three groups were injected intrathecally with 0.03 ml of the different test substances: (group 1) 16.7% magnesium sulphate {50% magnesium sulphate (0.01 ml) + 0.9% sodium chloride (0.02 ml)}; (group 2) 50% magnesium sulphate (0.01 ml) + 0.5% bupivacaine (0.02 ml); (group 3) 0.33% bupivacaine {0.5% bupivacaine (0.02 ml) + 0.9% sodium chloride (0.01 ml)}.
RESULTS
Sensory blockade in the hindlimbs was observed only in group 2 and lasted for 12 to 14 minutes, while there were no sensory blockades in group 1 and group 3.
CONCLUSIONS
Magnesium sulphate potentiated the analgesic effect of bupivacaine when coadministered intrathecally with bupivacaine in rats. These results suggest that intrathecal administration of magnesium sulphate may be a useful adjunct to spinal bupivacaine anesthesia. |
| Key Words:
Anesthetic techniques: intrathecal; Pharmacology: bupivacaine; magnesium sulphate |
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