Magnesium Sulfate Diminishes the Effects of Amide Local Anesthetics in Rat Sciatic-Nerve Block

MgSO4 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 MgSO4 at the LA receptor within the Na+ channel.