Metabolsim of vasodilator 4-(3,4,5-trimethoxycinnamoyl)-1-(1-pyrrolidinyl)carbonylmethylpiperazine (cinepazide): isolated and identification of metabolites in the rat and man.

Abstract

Further study on identification of metabolites of cinepazide, 4-(3,4,5-trimethoxycinamoyl)-1-(1-pyrrolidinyl)carbonylmethylpiperazine, in rats and men was carried out. New metabolites of cinepazide in rat urine were 4-[1-[4-(3,4,5-trimethoxycinnamoyl)-piperazinly]acetamidol-1-butanol (M-II), 4-(3,4,5-trimethoxycinnamoyl)-1-[1-(hydroxypyrrolidinyl)]carbonylmerthylpiperazine (M-IV) and 4-[1-[4-(3,4,5-trimethoxycinnamoyl)piperazinyl]acetamidol]-1-butyric acid (M-VI). Structures of two mono-O-demethylated metabolites of cinepazide predicted in the previous paper were assigned as 3-hydroxy-4,5-dimethoxycinnamoyl and 4-hydroxy-3,5-dimethoxycinnamoyl compounds (M-III and M-V) by the FT-NMR spectrometry measured in a mixture of CDC13-C6D6 (1:1, v/v) after methylation with dimethylsulfare-d6. The corresponding pyrrolidone metabolite of cinepazide was undetectable in rat urine. New metabolites of cinepazide in rat feces were found to be 4-(3,5-dihydroxy-phenethylcarbonyl)-1-(1-pyrrolidinyl)carbonylmethylpiperazine (M-VIII) and 4-(3,5-dihydroxycinnamoyl)-1-(1-pyrrolidinyl)carbonylmethylpiperazine (M-IX). Metabolites of cinepazide in human urine were studied by both methods--high performance liquid chromatography and mass spectrometry with ion cluster technique. Unchanged drug was mainly excreted in the urine, and M-VI was the major urinary metabolite. The existence of M-IV and M-V was suggested by high performance liquid chormatography. The corresponding pyrrolidone was also undetectable in human urine.