Metabolism and disposition of n-butyl acrylate in male Fischer rats.

Butyl acrylate (BA) is one of the major monomers used in the manufacture of polymers and resins. Because little is known regarding its metabolic fate in animals, it was of interest to study the metabolism and disposition of BA in the rat. After oral administration, butyl [2,3-14C]acrylate was rapidly absorbed and metabolized. The acrylate moiety was metabolized primarily to CO2, accounting for elimination of up to 75% of the administered radiolabel. Elimination in urine and feces accounted for approximately 10 and 2% of the dose, respectively. Initial clearance of radioactivity from the tissues was very rapid and then decreased to a negligible rate 2 hr after iv administration. Total radioactivity in the major tissues was relatively constant from 2 to 24 hr. The majority of the radioactivity in the blood at 24 hr was found to be covalently bound to the protein fraction of the red blood cell membranes. There was some evidence of a first-pass effect when BA was administered by gavage because iv administration resulted in less metabolism to CO2 and quantitative differences in urinary metabolites. The two major metabolites in urine were identified as N-acetyl-S-(2-carboxyethyl)cysteine and N-acetyl-S-(2-carboxyethyl)cysteine-S-oxide. Results of this study indicated that the major portion of a BA dose was hydrolyzed to acrylic acid, which was further metabolized to compounds available for oxidative metabolism. Radiolabeled carbons from the BA molecule were excreted as CO2 or incorporated in trace amounts into lipids, proteins, and other products of de novo synthesis. A smaller portion of the BA dose was conjugated with endogenous glutathione.(ABSTRACT TRUNCATED AT 250 WORDS)