How is phenylephrine metabolized?

How is phenylephrine metabolized?

• A. COMT only
• B. Both MAO and COMT
• C. Not metabolized
• D. MAO only

Answer: (D)

Phenylephrine is metabolized primarily by monoamine oxidase (MAO) rather than by COMT because of its chemical structure. It is a noncatecholamine amine, meaning its aromatic ring does not carry the two adjacent hydroxyl groups (a catechol) that COMT targets for methylation. MAO in the gut and liver oxidatively deaminates such amines, rapidly inactivating phenylephrine. Since COMT acts mainly on catecholamines with the catechol structure, its role in metabolizing phenylephrine is minimal. Therefore MAO is the primary (and effectively sole) metabolic route.

Phenylephrine is metabolized primarily by monoamine oxidase (MAO) rather than by COMT because of its chemical structure. It is a noncatecholamine amine, meaning its aromatic ring does not carry the two adjacent hydroxyl groups (a catechol) that COMT targets for methylation. MAO in the gut and liver oxidatively deaminates such amines, rapidly inactivating phenylephrine. Since COMT acts mainly on catecholamines with the catechol structure, its role in metabolizing phenylephrine is minimal. Therefore MAO is the primary (and effectively sole) metabolic route.