Studies on the Metabolism of Sympathomimetic Amines. The Metabolism of (±)-[¹⁴C] Adrenaline in the Horse

Abstract

1. The metabolism of (±)-[¹⁴C]adrenaline has been studied in two horses after intravenous administration.

2. The plasma half-life of ¹⁴C was 228 min (Horse A) and 100 min (Horse B).

3. Excretion of ¹⁴C in the urine in 20 h was 90% (A) and 70% (B). Over 94% of the excreted radioactivity has been identified.

4. The two horses differed in their metabolism of adrenaline. Unchanged drug accounted for 11% (A) and 20% (B), and for A and B respectively, metabolites excreted were 3-methoxyadrenaline (10%, 21%), 4-hydroxy-3-methoxymandelic acid (16%, 13%), 3,4-dihydroxyphenylglycol (6%, 0%), 4-hydroxy-3-methoxyphenylglycol (10%, 3%), 3,4-dihydroxybenzoic acid (5%, 0%), 3,4-dihydroxymandelic acid (7%, 3%) and 4-hydroxy-3-methoxybenzoic acid (18%, 4%).