Urinary metabolites of the new progestagen STS 557 (17 alpha-cyanomethyl-17-hydroxy-4,9-estradien-3-one) in the dog and rat.

Urinary metabolites of the new progestagen STS 557 (17 alpha-cyanomethyl-17-hydroxy-4,9-estradien-3-one) were isolated and characterized following oral administration of the 14 alpha, 15 alpha-tritium labelled compound to dogs and rats. 17 alpha-Cyanomethyl-11 beta, 17-dihydroxy-4,9-estradien-3-one (11 beta-OH-STS 557) and 17 alpha-cyanomethyl-1,3,5(10),9(11)-estratetraene-3,17-diol were identified by comparison with synthesized reference compounds. Mass spectra data indicate the following other pathways of STS 557 biotransformation: Hydroxylation in other positions than 11; hydrogenation; hydroxylation + hydrogenation; alteration of the 17 alpha-side chain.