Local anesthetics (LAs) are nonselective voltage-gated sodium channel blockers. This nonselective blockade is not only the source of LAs’ efficacy in blocking action potentials in Aδ and C fibers, but it is also responsible for LAs toxic properties related to the blockade of other sensory, motor, and autonomic fibers. Toxic reactions (Table 14) may result from (1) excessive dosage, (2) repeated doses, (3) rapid absorption, (4) unintentional intravascular injection, (5) low plasma protein binding, and (5) slow metabolism or elimination of the LA or its metabolites.
Table 14. Local Anesthetic Toxicity.
|Signs and symptoms: