The transformation from amitriptyline to nortriptyline occurs by which process?

The transformation from amitriptyline to nortriptyline occurs by which process?

• A. Ketone reduction
• B. Epoxidation
• C. Aromatic hydroxylation
• D. N-demethylation

Answer: (D)

N-demethylation. Amitriptyline has a tertiary amine, and nortriptyline is the same structure with one methyl group removed from that nitrogen, turning it into a secondary amine. This oxidative dealkylation is a common hepatic metabolic step, typically mediated by cytochrome P450 enzymes. The change is specific to removing a methyl group from nitrogen, not introducing new atoms or altering other parts of the molecule. The other processes describe different types of chemical changes—reducing a carbonyl, forming an epoxide, or adding a hydroxyl to an aromatic ring—that don’t convert a tertiary amine into a secondary amine.

N-demethylation. Amitriptyline has a tertiary amine, and nortriptyline is the same structure with one methyl group removed from that nitrogen, turning it into a secondary amine. This oxidative dealkylation is a common hepatic metabolic step, typically mediated by cytochrome P450 enzymes. The change is specific to removing a methyl group from nitrogen, not introducing new atoms or altering other parts of the molecule. The other processes describe different types of chemical changes—reducing a carbonyl, forming an epoxide, or adding a hydroxyl to an aromatic ring—that don’t convert a tertiary amine into a secondary amine.