What is a characteristic of amide local anesthetics compared to esters?

Amide local anesthetics are known for their longer duration of action compared to esters. This characteristic is largely due to the chemical structure of amides, which allows them to have a more stable presence in the body, resulting in a prolonged effect. Amides are metabolized in the liver, and their breakdown products tend to be less potent. In contrast, esters, which are typically hydrolyzed by plasma enzymes, usually have a shorter duration of action because they are metabolized more rapidly.

The longer duration of action of amides can be particularly beneficial in clinical settings where sustained numbing is required, allowing for extended procedures without the need for frequent reinjection. This is one of the reasons why amide anesthetics are often preferred for various dental and medical procedures.

In summary, the defining characteristic of amide local anesthetics that distinguishes them from esters is their longer duration of action, making them a favorable choice in many clinical applications.