[Evaluation in vitro of the local anesthetic effect by means of the dose/stabilization effect curve].

The effect "in vitro" and "in vivo" of local anesthetics is normally evaluated at fixed time or considering the time required to obtain a per cent effect. We have attempted to estimate the dose/effect correlation at steady state using "in vitro" preparation of sciatic nerve-trunk of frog. Such an experiment is possible only if the concentrations of drugs tested are lower than those used in previous methods, so as not to inhibit the nerve fibres completely. The drugs tested were: lidocaine, procaine, promethazine and imipramine. Using linear regression analysis, it is possible to compare both the DE50 of the drugs tested and slopes of linear regression. In this manner we can better characterize the pharmacodynamic properties of local anesthetics.