A note on the metabolism of 5 alpha-androst-16-en-3-one in the young boar in vivo.

The metabolism of plasma 5 alpha-androst-16-en-3-one (androstenone) was studied in two young boars weighing about 100 kg in which a single dose of tritiated androstenone was injected intravenously. The peripheral blood of one boar was continuously sampled for 6 h after injection; the total radioactivity per liter of plasma increased up to 14 min after the injection, and then declined rather slowly since plasma radioactivity was still measurable 7 days after injection. The metabolic clearance rate of androstenone was calculated to be about 80 000 liters per day. This quick disappearance of plasma androstenone was probably mainly due to storage in fatty tissue and, to a lesser extent, to catabolism into 5 alpha-androst-16-en-3 alpha-ol, 5 alpha-androst-16-en-3 beta-ol and particularly into unknown more polar compounds of which there were at least three. Radioactivity was mainly eliminated in the urine in the form of the same unknown polar compounds.