The intravenous toxicity of local anesthetic agents in man

Abstract

The toxicity of ,two hydrolyzable (meprylcaine and isobucaine) and a nonhydrolyzable (mepivacaine) local anesthetic agents was determined in man. The drugs were administered continuously, intravenously at rates proportional to concentrations commonly used in regional anesthesia. Toxicity was assumed to be inversely proportional to the tolerated length of infusion. The results of this study were compared with those obtained in a similar investigation carried out with three other hydrolyzable (procaine, 2‐chloroprocaine, and tetracaine) and a nonhydrolyzable (lidocaine) local anesthetic agents. The results of both studies indicate that, with onc exception (isobucaine), the rapidly hydrolyzable anesthetics (meprylcaine and 2‐chloroprocaine) are less toxic than the nonhydroly.wble or more slowly hydrolyzable ones. After discontinuation of infusion, signs and symptoms of systemic tOXicity disappear most rapidly with the two rapidly hydrolyzable local anesthetics.