Amino esters

Amino esters are a class of local anesthetics. They are named for their ester bond and are unlike amide local anaesthetics.

Structure

Structurally, amino esters consist of three molecular components:

• a lipophilic part (ester)
• an intermediate aliphatic chain
• a hydrophilic part (amine)

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 esters, in reference to anesthetic agents, are rapidly metabolized in the plasma by butyrylcholinesterase to para-aminobenzoic acid derivatives, then excreted in the urine. This suggests their very short half lives. Allergy is more likely to occur with ester-type agents, as opposed to amide-type.

Examples

Amino ester-type include:

• Cocaine
• Procaine (Novocain)
• Tetracaine (Pontocaine)
• Benzocaine
• Chloroprocaine

References

• University of Texas Med School, Pharmacology Syllabus.
• Katzung. 10th edition. Chapter 26.