Analysis of 1, 4-Dimorpholino-7-phenylpyrido [3, 4-d] pyridazine (DS-511) and Its Metabolites in Biological Specimens. I. Identification of Metabolites in Rat Urine and Dog Urine and Bile

The metabolic fate of 1, 4-dimorpholino-7-phenylpyrido [3, 4-d] pyridazine (DS-511) was studied in the rat and the dog. Urine and bile were extracted with ethyl acetate before and after enzymatic hydrolysis and separated into lipophilic and hydrophilic fractions. The structures of seven lipophilic and two hydrophilic metabolites obtained on thin-layer chromatograms were investigated by comparing their ultraviolet, infrared and nuclear magnetic resonance spectra, Rf values on thin-layer chromatograms and other physicochemical properties with those of synthetic samples. The main metabolites were 7-(4-hydroxyphenyl)-1, 4-dimorpholinopyrido [3, 4-d] pyridazine and 4-[N-carboxymethyl-N-(2-hydroxyethyl) amino]-1-morpholino-7-phenylpyrido [3, 4-d] pyridazine. In addition, 7-(4-hydroxy-3-methoxyphenyl)-1, 4-dimorpholinopyrido [3, 4-d] pyridazine and 7-(4-hydroxy-3-methoxyphenyl)-4-morpholinopyrido [3, 4-d] pyridazin-1 (2H)-one were observed as minor metabolites in the dog and the rat, respectively.