Chloroprocaine can be given in relatively large doses with a very low risk of systemic toxicity and has the shortest duration of action among clinically used local anaesthetics. What explains both properties?

• A High protein binding limits its entry into the central nervous system
• B Its low pKa prevents penetration of the blood-brain barrier
• C It is rapidly hydrolysed by plasma pseudocholinesterase into inactive metabolites ✓
• D It undergoes extensive hepatic first-pass metabolism

Explanation

Chloroprocaine is an ester local anaesthetic cleaved almost instantly by plasma pseudocholinesterase, giving a plasma half-life measured in seconds to minutes. This rapid hydrolysis both limits systemic accumulation, permitting high doses, and accounts for its very short clinical duration. Esters are not protein bound to any relevant degree, their pKa is unremarkable, and hepatic metabolism characterises the amide group, not the esters.

Reference: Morgan and Mikhail Clinical Anesthesiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.