Which type of local anesthetic is typically broken down by blood enzymes and is less effective?

Ester local anesthetics are typically broken down by plasma cholinesterase enzymes in the blood, which is a key distinguishing feature of this class compared to amide local anesthetics that are metabolized primarily in the liver. This enzymatic breakdown can lead to a shorter duration of action for ester local anesthetics, making them less effective for procedures that require a longer analgesic effect. Additionally, the rapid metabolism of esters can lead to a more unpredictable pharmacokinetic profile when compared to amides.

Ester local anesthetics are also more likely to cause allergic reactions, which can further limit their effectiveness in certain patient populations. This combination of factors contributes to the perception that they are less effective for prolonged pain management compared to their amide counterparts, which are typically more stable and have a more robust duration of action due to their metabolic pathways.

Thus, they are often reserved for specific situations, such as topical anesthesia or brief procedures, rather than for longer or more complex interventions where longer-lasting analgesia is required.