A patient with an allergy to lidocaine needs profound local anesthesia. Lidocaine belongs to the amide class. Which ester-class local anesthetic can be used?

Correct answer: C. Tetracaine

• A. Bupivacaine is an amide — same class as lidocaine.
• B. Mepivacaine is an amide — same class as lidocaine.
• C. Correct. Tetracaine is an ester-class local anesthetic. In cases of true amide allergy, switching to an ester is appropriate because they are metabolized differently (plasma cholinesterase for esters vs. liver for amides) and have different allergenicity.
• D. Articaine is an amide with a thiophene ring — same class as lidocaine. Cross-reactivity possible.