Concepedia

Abstract

L‐2‐ 14 C‐3‐methoxy, 4‐hydroxyphenylalanine (L‐ 14 C‐O‐methyldopa) has a biological half‐life of approximately 15 hours in human blood. 3‐Methoxy, 4‐hydroxyphenyllactic acid, homovanillic acid, and 3,4‐dihydroxyphenylacetic acid are metabolites found in the blood. The urinary excretion of radioactivity is slow and only a small proportion of excreted radioactivity represents unchanged O‐methyldopa. The same metabolites are found as in the blood as weU as small amounts of dopa, dopamine, and 3‐methoxytyramine. It is concluded that in man part of the L‐O‐methyldopa undergoes demethylation to dopa, which is further metabolized to dopamine and phenolcarboxylic acids.