Metabolism of 3-Hydroxyanthranilic Acid-Carboxyl-C 14 in the Human. ∗

Summary

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.