RT Journal Article SR Electronic T1 THE EXCRETION OF N15 IN THE URINE OF DOGS AFTER THE ADMINISTRATION OF LABELED PENTOBARBITAL JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 364 OP 366 VO 90 IS 4 A1 VAN DYKE, H. B. A1 SCUDI, JOHN V. A1 TABERN, D. L. YR 1947 UL http://jpet.aspetjournals.org/content/90/4/364.abstract AB After the oral administration of sodium pentobarbital (Nembutal) labeled with N15, dogs excreted about 60% of the total dose of excess N15 in the urine during the first 24 hours. The excess N15 in the urinary ammonia and urea represented less than 8% of the N15 so that more than 92% was excreted as pentobarbital or metabolic degradation products derived from the drug. In one isotope-dilution experiment, about 3% of the total excess N15 in the urine was found to be pentobarbital; this finding confirms the conclusion of other investigators that only minute amounts of pentobarbital are excreted unchanged. Possible structures of the major excretion product or products remain to be considered. 1946 by The American Society for Pharmacology and Experimental Therapeutics