The metabolism of norethandrolone in the horse: characterization of 16-, 20- and 21-oxygenated metabolites by gas chromatography/mass spectrometry

After oral administration to a thoroughbred gelding, the anabolic steroid norethandrolone was converted into a complex mixture of oxygenated metabolites. These metabolites were extracted from the urine, deconjugated by methanolysis and converted to their O‐methyloxime trimethylsilyl derivatives. Gas chromatographic/mass spectrometric analysis indicated the major metabolites to be 19‐norpregnane‐3,16,17‐triols, 19‐norpregnane‐3,17,20‐triols and 3,17‐dihydroxy‐19‐norpregnan‐21‐oic acids. Some minor metabolites were also detected. Copyright © 2001 John Wiley & Sons, Ltd.