In vivo metabolism of the anti-inflammatory agent 2-(5-ethylpyridin-2-yl)benzimidazole.

The metabolic fate of anti-inflammatory agent 2-(5-ethylpyridin-2-yl)benzimidazole (KB-1043) was studied in rats after oral administration. An average of 12.2 +/- 1.5% of the dose was excreted in the urine in the course of 0-48 h; 56.7 +/- 2.6% with feces. Two metabolites were also detected in the urine and isolated by reverse phase HPLC. Structures have been given after identification by comparison with authentic samples. The more abundant metabolite proved to be 2-(5-(1-hydroxyethyl)pyridin-2-yl)benzimidazole, a benzylic oxidation product, which was also excreted as glucuronic acid conjugate; the other metabolite was confirmed to be 2-(5-acetylpyridin-2-yl)benzimidazole. Carrageenin edema and gastric ulcerogenic activity were also tested for the two identified metabolites.