[An electrophysiological study of ropivacaine on excised cervical vagus nerves of rabbit]

Ropivacaine, a new long acting local anaesthetic of amide type is structurally related to mepivacaine and bupivacaine. This study was designed to compare the in vitro potency and neurotoxicity of ropivacaine with those of other commercially available local anaesthetics using an isolated rabbit vagus nerve model. Ropivacaine dose-dependently suppressed the evoked compound action potentials of A beta nerve and C nerve components. Minimum concentration of ropivacaine for producing complete suppression of the compound action potentials of all components was 0.008%. Electron microscopic observation showed that ropivacaine did not destroy any peripheral nervous structures in concentrations up to 0.75%. When the neurotoxic effect of ropivacaine was compared, in terms of risk ratio (clinically used concentration/concentrations producing 2 hr irreversible block), with that of commercially available local anesthetics, the rank oder was dibucaine, tetracaine, lidocaine, bupivacaine and ropivacaine.