What are the chemical properties of anesthesia used in infraorbital nerve block?

Updated: Jun 14, 2018
  • Author: Karen M Byrne, MD; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Most local anesthetic agents share the same basic chemical structure, which consists of an aromatic ring, linked to an intermediate chain, linked to a hydrophilic amine segment. The intermediate chain between the aromatic and hydrophilic segments is either an ester or an amide. The chemical structure of this intermediate group classifies the agent into the amide group or the ester group. This structural difference determines the pathway by which the agent is metabolized and its allergic potential. For example, amino amides undergo hepatic metabolism, whereas amino esters are metabolized in the plasma via pseudocholinesterases. Hydrolysis of amino ester compounds yields para -aminobenzoic acid (PABA), a well-known allergen, as an intermediate metabolite. Thus, amino esters are significantly more likely than amino amides to cause true allergic reactions.

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