THE ALCOHOLIC METABOLITES OF PENTOBARBITAL AND AMOBARBITAL IN MAN

¹ Department of Pharmacology and Experimental Therapeutics, The Johns Hopkins University, School of Medicine, Baltimore, Maryland

In normal human subjects the metabolites of 100- to 500-mg doses of N¹⁵-labeled pentobarbital or amobarbital were gradually eliminated in the urine over the course of 5 days. Isotope dilution experiments revealed that 51 to 73% of the N¹⁵ excreted after a 500-mg dose of amobarbital could be accounted for as 5-ethyl-5-(3-hydroxy-3-methyl) barbituric acid. The dextrorotatory and levorotatory diastereoisomers of 5-ethyl-5-(3-hydroxy-1-methyl butyl)barbituric acid accounted for 7 to 8% and 40 to 43%, respectively, of the urinary isotope derived from a 500-mg dose of pentobarbital.