Chloroprocaine is an ester local anesthetic that is rapidly metabolized by which enzyme?

Chloroprocaine is an ester local anesthetic that is rapidly metabolized by which enzyme?

• A. Pseudocholinesterase
• B. Acetylcholinesterase
• C. Hepatic esterase
• D. Plasma lipase

Answer: (A)

Esters are inactivated very quickly by plasma esterases, which gives chloroprocaine its ultrashort duration. The enzyme responsible in the bloodstream is pseudocholinesterase (butyrylcholinesterase), which hydrolyzes chloroprocaine almost immediately after administration. Acetylcholinesterase functions mainly at cholinergic synapses and is not the primary enzyme for hydrolyzing ester local anesthetics. Hepatic esterase would imply liver metabolism, which is not the main pathway for chloroprocaine, and plasma lipase does not hydrolyze ester local anesthetics. In cases of pseudocholinesterase deficiency, ester local anesthetics can have a longer effect, but under normal circumstances this plasma enzyme drives the rapid metabolism and short action of chloroprocaine.

Esters are inactivated very quickly by plasma esterases, which gives chloroprocaine its ultrashort duration. The enzyme responsible in the bloodstream is pseudocholinesterase (butyrylcholinesterase), which hydrolyzes chloroprocaine almost immediately after administration. Acetylcholinesterase functions mainly at cholinergic synapses and is not the primary enzyme for hydrolyzing ester local anesthetics. Hepatic esterase would imply liver metabolism, which is not the main pathway for chloroprocaine, and plasma lipase does not hydrolyze ester local anesthetics. In cases of pseudocholinesterase deficiency, ester local anesthetics can have a longer effect, but under normal circumstances this plasma enzyme drives the rapid metabolism and short action of chloroprocaine.