Metabolism of methandrostenolone in the horse: a gas chromatographic-mass spectrometric investigation of phase I and phase II metabolism.
The phase I and phase II metabolism of the anabolic steroid methandrostenolone was investigated following oral administration to a standardbred gelding. In the phase I study, metabolites were isolated from the urine by solid-phase extraction, deconjugated by acid catalysed methanolysis and converted to their O-methyloxime trimethylsilyl derivatives. GC-MS analysis indicated the major metabolic processes to be sequential reduction of the A-ring and hydroxylation at C6 and C16. In the phase II study, unconjugated, beta-glucuronidated and sulfated metabolites were fractionated and deconjugated using a combination of liquid-liquid extraction, enzyme hydrolysis, solid-phase extraction and acid catalysed methanolysis. Derivatization followed by GC-MS analysis revealed extensive conjugation to both glucuronic and sulfuric acids, with only a small proportion of metabolites occurring in unconjugated form.
McKinney
A R
AR
School of Chemistry, University of Sydney, NSW, Australia.
Ridley
D D
DD
Suann
C J
CJ
D000284:Administration, Oral; D045930:Anabolic Agents / Q000008:administration & dosage / Q000652:urine*; D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry; D006736:Horses; D008297:Male; D008696:Methandrostenolone / Q000008:administration & dosage / Q000652:urine*; D021241:Spectrometry, Mass, Electrospray Ionization
D045930:Anabolic Agents; D008696:Methandrostenolone