Amino esters

Structurally, local anesthetics consist of three molecular components:


 * a lipophilic part
 * an intermediate aliphatic chain
 * a hydrophilic (amine) part

The chemical linkage between the lipophilic part and the intermediate chain can be of the amide-type or the ester-type, and is the general basis for the current classification of local anesthetics.

Amino ester-type include:


 * Cocaine
 * Procaine (Novocain)
 * Tetracaine (Pontocaine)
 * Benzocaine

Amino esters, in reference to anesthetic agents, are rapidly metabolized in the plasma by butyrlcholinesterase to para-aminobenzoic acid derivatives, then excreted in the urine. This suggests their very short ½ lives.

Allergy is more likely to occur with ester-type agents, as opposed to amide-type.

Reference

 * UT Med School, Pharmacology Syllabus.
 * Katsung. 10th edition. Chapter 26.