This course examines the clinical selection and use of ester- and amide-type local anesthetics with a clear focus on how their chemistry drives metabolism, duration, potency, and allergy risk. You’ll compare rapid plasma-metabolized esters like procaine, tetracaine, cocaine, and benzocaine with liver-metabolized amides such as lidocaine, mepivacaine, prilocaine, and bupivacaine—understanding how conditions like hepatic dysfunction, cholinesterase deficiency, or methemoglobinemia influence drug choice. Practical guidance covers formulation differences, onset and duration across clinical applications, toxicity considerations, vasodilatory effects, and strategies to safely tailor anesthetic selection for diverse patients and procedures.