Which local anesthetic is a para-aminobenzoic acid (PABA) derivative?

• A. Cocaine
• B. Procaine
• C. Bupivacaine
• D. Lidocaine

Answer: (B)

This question hinges on recognizing which local anesthetic is built from para-aminobenzoic acid (PABA) as an ester derivative. Procaine is the classic ester local anesthetic formed by linking PABA to diethylaminoethanol via an ester bond, so its structure is a PABA derivative. Cocaine, while an ester, is a tropane alkaloid with a different origin and pharmacology, not a PABA derivative. Lidocaine and bupivacaine are amide-type anesthetics; they contain an amide linkage rather than an ester derived from PABA, so they don’t fit the PABA-derivative pattern. Therefore, procaine is the one that fits as a PABA derivative.