If a patient has atypical plasma cholinesterase, which type of local anesthetic should not be used?

Atypical plasma cholinesterase is a genetic condition that affects the metabolism of certain esters, particularly those used as local anesthetics. In patients with this condition, the enzyme that breaks down esters is dysfunctional or present in lower quantities. This can lead to prolonged effects of ester local anesthetics and increased risk of toxicity.

Esters, such as procaine and tetracaine, are metabolized by plasma cholinesterase in the bloodstream. Since patients with atypical plasma cholinesterase cannot adequately metabolize these anesthetics, the duration of their action is significantly extended and can cause adverse reactions or prolonged anesthetic effects. Therefore, if a patient has atypical plasma cholinesterase, the use of ester local anesthetics is contraindicated.

Amides, on the other hand, are metabolized primarily in the liver and are not affected by plasma cholinesterase activity. This means that they are safe to use in patients with atypical plasma cholinesterase, making them a better option for anesthesia in this population. Recognizing the differences in the metabolism of these local anesthetics is crucial for patient safety and effective pain management.