Which type of local anesthetic is typically preferred for patients with a history of allergic reactions?

Amide-type anesthetics are generally preferred for patients with a history of allergic reactions due to their chemical structure and the way they are metabolized in the body. Amides are typically less likely to cause allergic reactions compared to ester-type anesthetics. This reduced risk is attributed to the fact that amide type anesthetics have a more stable molecular structure and are primarily metabolized in the liver, which does not involve the same intermediates that can trigger allergic responses.

In contrast, ester-type anesthetics are metabolized by plasma esterases, which can produce byproducts that are more likely to induce hypersensitivity reactions in susceptible individuals. Patients with a known history of allergy, particularly to local anesthetics, often have a higher likelihood of reacting to esters than amides.

Buffered local anesthetics are intended to improve the pH of the anesthetic solution, thereby enhancing the effectiveness and comfort of the injection, but they do not address the underlying allergy risk related to the type of agent being used.

Overall, amide-type anesthetics provide a safer alternative for patients with allergies, as they have a lower incidence of allergic reactions and are well-tolerated in the majority of cases.