Comparisons of the Anesthetic Potency and Intracellular Concentrations of S(−) and R() Bupivacaine and Ropivacaine in Crayfish Giant Axon in Vitro

Abstract

S(-) bupivacaine has a more potent phasic blocking effect than ropivacaine or R(+) bupivacaine in crayfish giant axons in vitro. An equivalent intracellular local anesthetic concentration for the three anesthetics was found, suggesting that the intracellular cationic local anesthetic concentration is not directly correlated with the intensity of block.