16-oxygenation of 17 -methyltestosterone in rabbits

Metabolism of stanozolol: identification and synthesis of urinary metabolites

Urinary metabolites of stanozolol (17 alpha-methyl-17 beta-hydroxy-5 alpha-androst-2-eno(3,2-c)-pyrazole) following oral administration were isolated by chromatography on XAD-2 and by preparative high-performance liquid chromatography (HPLC) and identified by gas chromatography-mass spectrometry (GC/MS) with electron impact (EI)-ionisation. Stanozolol is excreted as a conjugate but is metabolized to a large extent. All identified metabolites are hydroxylated, namely at C-3' of the pyrazole ring and at C-4 beta, C-16 alpha and C-16 beta of the steroid. Less than 5% of the metabolites are found in the unconjugated urine fraction: 3'-hydroxy-stanozolol (II) and 3'-hydroxy-17-epistanozolol (III). Conjugated excreted metabolites are 3'-hydroxystanozolol (II), stanozolol (I), 4 beta-hydroxy-stanozolol (IV), 16 beta-hydroxystanozolol (V), 16 alpha-hydroxystanozolol (VI), two isomers of 3',16-dihydroxystanozolol (VII, VIII), two isomers of 4 beta, 16-dihydroxystanozolol (IX, X) and a 3',?-dihydroxystanozolol (XI). 3'-Hydroxystanozolol, 4 alpha-hydroxystanozolol, 4 beta-hydroxystanozolol, 16 alpha-hydroxy-, 16 alpha-hydroxy-17-epi- and 16 beta-hydroxystanozolol were synthesised to confirm the structural assignment of the main metabolites.

Metabolism of 17 alpha-methyltestosterone in the rabbit: C-6 and C-16 hydroxylated metabolites

17 alpha-Methyltestosterone and the reduced metabolites, 17 alpha-methyl-5 alpha-androstane-3 alpha, 17 beta-diol, 17 alpha-methyl-5 alpha-androstane-3 beta, 17 beta-diol and 17 alpha-methyl-5 beta-androstane-3 alpha, 17 beta-diol, together with three hydroxylated metabolites, 17 alpha-methyl-5 beta-androstane-3 alpha, 16 alpha, 17 beta-triol, 17 alpha-methyl-5 beta-androstane-3 alpha, 16 beta, 17 beta-triol and a new metabolite, 17 alpha-methyl-5 alpha-androstane-3 beta, 6 alpha, 17 beta-triol, were isolated and identified in the urine of rabbits dosed with 17 alpha-methyltestosterone. No hydroxylated 5 alpha-metabolite of 17 alpha-methyltestosterone has been identified previously. No of 17 alpha-methyltestosterone has been identified previously. No evidence for epimerization at the C-17 position was observed.

Metabolism of 17 alpha-methyl-5 beta-dihydrotestosterone in the rabbit

17 alpha-Methyl-5 beta-androstane-3 alpha,17 beta-diol together with the hydroxylated metabolites 17 alpha-methyl-5 beta-androstane-1 beta,3 alpha,17 beta-triol, 17 alpha-methyl-5 beta-androstane-3 alpha,12 beta,17 beta-triol, 17 alpha-methyl-5 beta-androstane-3 alpha,16 alpha,17 beta-triol and 17 alpha-methyl-5 beta-androstane-3 alpha,16 beta,17 beta-triol were isolated and identified in the urine of rabbits orally dosed with 17 alpha-methyl-5 beta-dihydrotestosterone. Biotransformations differ from the 5 alpha-series where hydroxylation occurred at C-6 and C-15. In both series, the C-3 equatorial epimer was the major urinary excretion product among the non-hydroxylated metabolites. The 5 beta-compound was more resistant to metabolic hydroxylation than the 5 alpha-compound. No evidence for epimerization at the C-17 position was observed.