Studies on disposition and metabolism of tolmetin, a new anti-inflammatory agent, in rats and mice. II. Urinary metabolites.

A new urinary metabolite of tolmetin was found in rat urine and identified as the hydroxymethyl metabolite (tolmetin-OH), an intermediate in the formation of the known carboxy metabolite (tolmetin-COOH). In rats of two strains, the following percentages of the urinary reactivity of [14Ia1tolmetin were found in 24 hr: unchanged tolmetin-COOH (58--60%), tolmetin-OH (18--24 %), and its conjugate 6--14%. Mouse urine contained the unchanged drug (about 20%), its conjugate and tolmetin-COOH (60%). Similarly to mouse urine, human urine contained negligible amounts of tolmetin-OH.