Metabolites of lynestrenol acetate in the bile of rats after intravenous administration; a comparison with lynestrenol
Coert, A.; Geelen, J.; van der Vies, J.
Acta Endocrinologica 78(4): 791-800
1975
ISSN/ISBN: 0001-5598 PMID: 1173966 DOI: 10.1530/acta.0.0780791Document Number: 510698
The metabolism of lynestrenol acetate (LA), an oral contraceptive, w as studied in female rats. LA is stable in gastric and intestinal juice in vitro, and is partly absorbed unchanged after oral administration. 40% of the radioactivity is excreted in the bile within 90 minutes, when labelled in the nucleus. Administration of LA labelled in the acetate group resulted in only 6% of the radioactivity in the bile, indicating that most of LA lost the acetate group during metabolism. Complex formation with silver shows that more than 80% of the metabolites of LA still contained the 17 alpha-ethinyl group. Thin layer analysis revealed that the major metabolite of (4 carbon-14)LA did not appear in the autoradiograms of (1" carbon-14)LA or (4 carbon-14)L. LA seems to be altered in the nucleus in the presence of the acetate group. IR, NMR and mas spectrophotometric analysis indicate the introduction of a 15 alpha hydroxyl group. A second major metabolite of LA and L seems to be 19-nor-17 alpha-pregn-20-yne-3 alpha, 17 beta-diol. These results indicate that esterification of a steroid can lead to alteration in the metabolic pathway of the free steroid.