Which local anesthetic is not an amide?

Which local anesthetic is not an amide?

• A. Procaine (Novocain)
• B. Lidocaine (Xylocaine)
• C. Articaine (Septocaine)
• D. Mepivacaine (Carbocaine)

Answer: (A)

Understanding the bond type in local anesthetics explains why this one is not an amide. Procaine is an ester-type local anesthetic, meaning it contains an ester linkage between the aromatic ring and its side chain. Esters are hydrolyzed quickly by plasma esterases, so they tend to have a shorter duration and historically a higher potential for hypersensitivity reactions due to PABA-related metabolites. The other drugs listed are amide-type anesthetics, which have an amide bond and are mainly metabolized in the liver by amidases, giving longer duration in clinical use. Articaine is a special case in some texts because it includes an ester group, but it is classified pharmacologically as an amide local anesthetic. So, the one that is not an amide is procaine.

Understanding the bond type in local anesthetics explains why this one is not an amide. Procaine is an ester-type local anesthetic, meaning it contains an ester linkage between the aromatic ring and its side chain. Esters are hydrolyzed quickly by plasma esterases, so they tend to have a shorter duration and historically a higher potential for hypersensitivity reactions due to PABA-related metabolites. The other drugs listed are amide-type anesthetics, which have an amide bond and are mainly metabolized in the liver by amidases, giving longer duration in clinical use. Articaine is a special case in some texts because it includes an ester group, but it is classified pharmacologically as an amide local anesthetic. So, the one that is not an amide is procaine.