THE METABOLISM OF AMYTAL LABELED WITH N¹⁵ IN DOGS

¹ Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York 32, N. Y.

After the oral administration of Amytal labeled with N¹⁵, dogs excreted about 41 per cent of the dose of excess N¹⁵ in the urine in the first 24 hours and 81 per cent in 48 hours. The excess N¹⁵ in the urinary ammonia was negligible; the urinary urea contained about 10 per cent of the dose.

Isotope dilution experiments with ethylisoamylbarbituric acid and the similarly substituted malonuric acid, acetyl urea and acetamide revealed that these compounds are excreted only in traces. These results prove that Amytal is not principally detoxified by simple hydrolysis of the barbituric acid ring.

The metabolic products of Amytal are excreted at about half the rate of those of pentobarbital.