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

Abstract

1. The metabolism of (±)-[¹⁴C]noradrenaline in horses has been studied. The plasma half-life of radioactivity following intravenous injection was 95 min.

2. Two horses each excreted about 80–85% of the radioactivity in the urine in 15 h after rapid intravenous injection and about 75% of the excreted radioactivity has been identified.

3. The unchanged drug in the urine accounted for less than 1% of the dose and 3-methoxynoradrenaline for about 7%. The main metabolites were 4-hydroxy-3-methoxymandelic acid (22%), 4-hydroxy-3-methoxybenzoic acid (13%) and 4-hydroxy-3-methoxyphenylglycol (11%). 3,4-Dihydroxyphenylglycol was a minor metabolite (5%).