Metoclopramide metabolism and determination by high-pressure liquid chromatography.

A high-pressure liquid chromatographic method suitable for determining plasma metoclopramide levels at normal (10-20 mg) doses is described. Eight metabolites as well as metclopramide were isolated and identified in rat, dog. and human urine. The only common metabolite in these species is 2-[(4-amino-5-chloro-2-methoxybenzoyl)-amino] acetic acid. N-Deethylation is a major pathway for metoclopramide metabolism in the lower animals but not in humans. Metoclopramide is excreted mainly unchanged or as its conjugates by humans.