Studies on the metabolism of arylacetic acids. 6. Comparative metabolic conjugation of 1- and 2-naphthylacetic acids in the guinea pig, mouse, hamster and gerbil

Abstract

1. The patterns of metabolic conjugation of the isomeric 1 - and 2-naphthylacetic acids have been compared in guinea pig, mouse, hamster and gerbil. Equimolar doses of [carboxy-¹⁴C]1- and 2-naphthylacetic acids were given to these species by i.p. injection, their urine collected and urinary metabolites examined by t.l.c. before and after treatment with β-glucuronidase or mild alkali.

2. Urinary excretion of ¹⁴C following administration of ¹⁴C-1-naphthylacetic acid was 76–93% of dose in 72 h, the bulk being eliminated in 24 h. Urinary metabolites comprised 1 -naphthylacetic-glycine and -glucuronide together with the unchanged acid.

3. Following administration of ¹⁴C-2-naphthylacetic acid, some 68–94% of the ¹⁴C dose was recovered in the urine in 72 h, with the majority in the 0–24h urine. All four species excreted 2-naphthylacetyl-glucuronide and -glycine: additionally, 2-naphthylacetyl-taurine was excreted by mouse, gerbil and hamster and the glutamine conjugate was also present in hamster urine.