Metabolism of 3-Hydroxyanthranilic Acid-Carboxyl-C14 in the Human.

1. Orally administered 3-hy-droxyanthranilic acid labeled with C14 in the carboxyl group was metabolized by a human subject with achondroplasia in such a manner that approximately 40% of the isotope appeared as C14O2 within 6 hours. 2. Within the first 24 hours 35% of the label appeared in the urine. Of this urinary activity, 80% was in quinolinic acid with smaller amounts present in nicotinic acid, N1-methylnicotina-mide, and N-methyl-2-pyridone-5-carboxa-mide. 3. The per cent of C14 appearing in the urinary metabolites corresponded more to the renal clearance pattern of the compounds rather than to their known precedence in the metabolic pathway from 3-hydroxyanthranilic acid to N-methyl-2-pyridone-5-carboxamide. 4. Appreciable radioactivity was found in blood serum during the first day, with an increasing percentage of the serum activity in a form precipitable with serum proteins.