Which class of local anesthetics has the longest duration of action?

Which class of local anesthetics has the longest duration of action?

• A. Esters
• B. Amides
• C. Phenols
• D. Alcohols

Answer: (B)

Amide local anesthetics are known for having the longest duration of action compared to other classes. This is primarily due to their chemical structure and the way they are metabolized in the body. Amides are metabolized by the liver, which typically provides a more consistent and prolonged effect compared to esters, which are metabolized by plasma cholinesterases and can have variable duration depending on the individual. Additionally, amides tend to have a higher lipid solubility, allowing them to bind more effectively to the target nerve tissue, leading to a longer duration of sensory blockade. This makes them suitable for procedures that require extended pain relief, while esters are often shorter-acting and can be affected by individual metabolic differences. Phenols and alcohols are not classified as local anesthetics in the same way, and while they can have anesthetic properties, they do not generally serve the primary function of long-duration local anesthesia. Thus, amides are distinctly recognized as having the longest duration among local anesthetic agents.

Amide local anesthetics are known for having the longest duration of action compared to other classes. This is primarily due to their chemical structure and the way they are metabolized in the body. Amides are metabolized by the liver, which typically provides a more consistent and prolonged effect compared to esters, which are metabolized by plasma cholinesterases and can have variable duration depending on the individual.

Additionally, amides tend to have a higher lipid solubility, allowing them to bind more effectively to the target nerve tissue, leading to a longer duration of sensory blockade. This makes them suitable for procedures that require extended pain relief, while esters are often shorter-acting and can be affected by individual metabolic differences.

Phenols and alcohols are not classified as local anesthetics in the same way, and while they can have anesthetic properties, they do not generally serve the primary function of long-duration local anesthesia. Thus, amides are distinctly recognized as having the longest duration among local anesthetic agents.