Metabolic fate of orally administered H3-norethynodrel in rabbits.

Abstract

The distribution of radioactivity in the urine, bile and feces of female rabbits following the oral administration of randomly tritiated 17α-ethynyl-17β-hydroxy- 5(10)-estrene-3-one has been measured. In 5 animals with bile drainage cannulae, 33 % of the administered radioactivity was excreted in the bile, 21% in the urine and 17% in the feces during 7 days. These results indicate that over 70% of the radioactivity was absorbed from the gut. In a control group of 3 normal and 2 sham-operated rabbits, 52% of the radioactivity was in the urine and 16 % in the feces, indicating that much of the activity in bile is reabsorbed and excreted in the urine. Less than 1 % of the radioactivity in bile was unconjugated, 81 % was conjugated as glucosiduronate and 18% as another conjugate, probably sulfate. Most of the glucosiduronate fraction was identified as 17α-ethynyl-3β,17β- dihydroxy-5(10)-estrene. In the urine, 1–2% of the radioactivity was unconjugated, 35–40% was glucosiduronate and 10–15% was sulfate. In the...