Etidocaine, bupivacaine, and lidocaine seizure thresholds in monkeys

The central nervous system toxicities of etidocaine, bupivacaine, and lidocaine were studied during constant-rate intravenous infusions in rhesus monkeys. Comparison of drug effects was achieved by determining the drug dosages and arterial plasma concentrations that induced electrical seizure activity. The central nervous system toxicity of etidocaine was similar to that of bupivacaine. The toxicity of each was four times greater than that of lidocaine. Since the drug infusion rates were proportional to anesthetic potencies in clinical usage, the therapeutic-toxic ratios of these three drugs are similar.