Which statement about local anesthetic metabolism is true?

Which statement about local anesthetic metabolism is true?

• A. Amides are metabolized in the liver.
• B. Esters are metabolized in the liver.
• C. Esters have lower allergy risk than amides.
• D. Amides are hydrolyzed by plasma cholinesterases.

Answer: (A)

Local anesthetic metabolism depends on the chemical class: amides are primarily cleared by hepatic enzymes in the liver, while esters are rapidly hydrolyzed in the blood by plasma cholinesterases. This is why the statement that amides are metabolized in the liver is true. Amide drugs such as lidocaine or bupivacaine rely on liver metabolism, so liver function can influence their duration and clearance. In contrast, esters are mainly broken down by plasma cholinesterases, not by the liver, which explains their faster onset and shorter duration. Allergy risk is typically higher with esters due to potential PABA-related hypersensitivity, not lower, and amides are not hydrolyzed by plasma cholinesterases.

Local anesthetic metabolism depends on the chemical class: amides are primarily cleared by hepatic enzymes in the liver, while esters are rapidly hydrolyzed in the blood by plasma cholinesterases. This is why the statement that amides are metabolized in the liver is true. Amide drugs such as lidocaine or bupivacaine rely on liver metabolism, so liver function can influence their duration and clearance. In contrast, esters are mainly broken down by plasma cholinesterases, not by the liver, which explains their faster onset and shorter duration. Allergy risk is typically higher with esters due to potential PABA-related hypersensitivity, not lower, and amides are not hydrolyzed by plasma cholinesterases.