Abstract: Chemical permeation enhancers (CPEs) improve access of local anesthetics to the nerve, thereby improving their performance. Surfactants, representing three CPE sub-groups: anionic, cationic, and nonionic surfactants, were co-injected with tetrodotoxin (TTX) or bupivacaine at the sciatic nerve of Sprague-Dawley rats. All enhancers produced marked concentration-dependent improvements in the frequency and duration of block with TTX but not bupivacaine. An in vitro toxicity assay showed a wide range of CPE myotoxicity, but in vivo histological assessment showed no signs of muscle or nerve damage at concentrations of CPEs that produced a half-maximal increase in the duration of block of TTX. There was no systematic relationship between the enhancers' charge or hydrophobicity and their enhancement of block duration or potency.

Abstract: Combinations of charged local anesthetics with chemical permeation enhancers have been developed to give long duration block which is selective for sensory block is greatly prolonged by combining the local anesthetic with a permeation enhancer. The selectivity of sensory over motor block is provided by selecting the concentration of the local anesthetic and the permeation enhancer to provide selective permeability of the sensory and motor neurons to the enhancer.

Abstract: Chemical permeation enhancers (CPEs) improve access of local anesthetics to the nerve, thereby improving their performance. Surfactants, representing three CPE sub-groups: anionic, cationic, and nonionic surfactants, were co-injected with tetrodotoxin (TTX) or bupivacaine at the sciatic nerve of Sprague-Dawley rats. All enhancers produced marked concentration-dependent improvements in the frequency and duration of block with TTX but not bupivacaine. An in vitro toxicity assay showed a wide range of CPE myotoxicity, but in vivo histological assessment showed no signs of muscle or nerve damage at concentrations of CPEs that produced a half-maximal increase in the duration of block of TTX. There was no systematic relationship between the enhancers' charge or hydrophobicity and their enhancement of block duration or potency.

Abstract: Combinations of charged local anesthetics with chemical permeation enhancers have been developed to give long duration block which is selective for sensory block over motor block. The duration of block is greatly prolonged by combining the local anesthetic with a permeation enhancer. The selectivity of sensory over motor block is provided by selecting the concentration of the local anesthetic and the permeation enhancer to provide selective permeability of the sensory and motor neurons to the enhancer.

Abstract: Chemical permeation enhancers (CPEs) improve access of local anesthetics to the nerve, thereby improving their performance. Surfactants, representing three CPE sub-groups: anionic, cationic, and nonionic surfactants, were co-injected with tetrodotoxin (TTX) or bupivacaine at the sciatic nerve of Sprague-Dawley rats. All enhancers produced marked concentration-dependent improvements in the frequency and duration of block with TTX but not bupivacaine. An in vitro toxicity assay showed a wide range of CPE myotoxicity, but in vivo histological assessment showed no signs of muscle or nerve damage at concentrations of CPEs that produced a half-maximal increase in the duration of block of TTX. There was no systematic relationship between the enhancers' charge or hydrophobicity and their enhancement of block duration or potency.

Abstract: Combinations of charged local anesthetics with chemical permeation enhancers have been developed to give long duration block which is selective for sensory block over motor block. The duration of block is greatly prolonged by combining the local anesthetic with a permeation enhancer. The selectivity of sensory over motor block is provided by selecting the concentration of the local anesthetic and the permeation enhancer to provide selective permeability of the sensory and motor neurons to the enhancer.