After oral administration of an antitussive, Eprazinone hydrochloride [1-(2-ethoxy-2-phenylethyl-4-(2-bezoylpropyl) piperazine dihydrochloride](I), two metabolites were identified from both urine and bile of rats, rabbits, and humans. Three Dragendorff reagentpositive spots were detected on thin-layer chromatograms of the benzene extracts from urine and bile. Methanol-eluted substance of each of the spots isolated from the thin-layer plate was submitted to gas-liquid chromatography, infrared spectroscopy, and rechromatography over thin-layer with the authentic Eprazinone [1-(2-ethoxy-2-phenylethyl)-piperazine](II), and 1-(2-hydroxy-2-phenylethyl) piperazine (III). These results suggested that II was a product formed by the cleavage of an N-C bond of the Mannich base moiety in Ia, and III was formed by its deethylation.
