Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Jul 2007
Magnesium sulfate diminishes the effects of amide local anesthetics in rat sciatic-nerve block.
Magnesium sulfate (MgSO(4)) is well known as an antagonist of N-methyl-d-aspartate receptors and was used for intrathecal analgesia a century ago. However, the effects of MgSO(4) combined with local anesthetics (LAs) on peripheral nerves are unclear. We tested the hypothesis that MgSO(4) could be used as an adjuvant to prolong and intensify conduction block by amide-type LAs in a rat sciatic-nerve block model. Further, the mechanism of possible synergy between LAs and MgSO(4) was investigated in whole-cell mode patch-clamp experiments. ⋯ MgSO(4) coadministered with amide-type LAs shortened the duration of sciatic-nerve block in rats. Therefore, it does not seem to be useful as an adjuvant for peripheral-nerve block. The mechanism of this observed antagonism is unclear but appears to be independent of the action of LAs and MgSO(4) at the LA receptor within the Na(+) channel.