What is the approximate half-life of chloroprocaine in plasma?

What is the approximate half-life of chloroprocaine in plasma?

• A. 15 seconds
• B. 45 seconds
• C. 2 minutes
• D. 10 minutes

Answer: (B)

Chloroprocaine is an ester anesthetic that is inactivated extremely quickly by plasma cholinesterases, so it has a very short time before its effects wear off. The plasma half-life is the time needed for the concentration to drop by half, and for chloroprocaine this occurs in tens of seconds. Clinically, about 30 to 60 seconds is typical, making 45 seconds a reasonable approximate value. This rapid metabolism explains its very brief duration of action and why systemic effects are unlikely unless the drug is given in large amounts or infused rapidly. The longer times listed would imply a much slower clearance, which doesn’t fit the rapid enzymatic inactivation of chloroprocaine.

Chloroprocaine is an ester anesthetic that is inactivated extremely quickly by plasma cholinesterases, so it has a very short time before its effects wear off. The plasma half-life is the time needed for the concentration to drop by half, and for chloroprocaine this occurs in tens of seconds. Clinically, about 30 to 60 seconds is typical, making 45 seconds a reasonable approximate value. This rapid metabolism explains its very brief duration of action and why systemic effects are unlikely unless the drug is given in large amounts or infused rapidly. The longer times listed would imply a much slower clearance, which doesn’t fit the rapid enzymatic inactivation of chloroprocaine.