Final answer:
Ester local anesthetics can cause allergic reactions due to the release of chemical mediators triggered by the immune system. Amide local anesthetics have a lower risk of allergic reactions as they are metabolized differently and do not elicit the same immune response.
Step-by-step explanation:
Ester local anesthetics can cause more allergic reactions because they can elicit an allergic response through the release of chemical mediators. When these anesthetics are administered for the first time, they can sensitize the immune system and trigger the production of specific IgE antibodies. Upon a second exposure to the ester local anesthetic, these IgE antibodies can bind to mast cells and trigger the release of chemical mediators, such as histamine, which can cause allergic symptoms.
For example, benzocaine is an ester local anesthetic that can cause allergic reactions. When benzocaine is used as a topical anesthetic, it can sensitize the immune system and lead to allergic reactions upon subsequent exposure. This is because benzocaine can bind to proteins in the skin, forming hapten-protein complexes that can initiate an immune response.
In contrast, amide local anesthetics, such as lidocaine, have a lower risk of allergic reactions because they do not elicit the same immune response as ester local anesthetics. Amide local anesthetics are metabolized differently in the body and do not form hapten-protein complexes that can trigger an allergic response.