The Biological Fate of Sodium Prasterone Sulfate after Vaginal Administration (III) : Metabolism in Pregnant Rats

The metabolism of sodium prasterone sulfate (PS) was investigated in pregnant rats after vaginal administration. Major metabolites in rat urine and bile were identified by means of thin layer chromatography/secondary ionization mass spectrometry and capillary gas chromatography/mass spectrometry. The urinary and biliary excretion of identified metabolites according to above menntioned methods were determined after vaginal administration of 14C-labelled PS. Main metabolites in the urine and bile were androst-5-ene-3β, 17β-diol 3-sulfate (3β, 17β-diol-MS) and androst-5-ene-3β, 17β-diol 3, 17-disulfate, respectively. Androst-5-ene-3β, 7α-diol 3-sulfate, androst-5-ene-3β, 7β-diol 3-sulfate and androst-5-ene-3β, 7α, 17β-triol 3-sulfate were also identified as minor metabolites in the urine and/or bile. Furthermore, the excretion ratio of unchanged PS in the urine and bile after vaginal administration was lower than that after intravenous one. PS was also converted to 3β, 17β-diol-MS during the incubation with the 9000 × g supernatant of the vaginal membrane including uterine cervix. These results suggest that a part of PS was metabolized to 3β, 17β-diol-MS during the process of the absorption after vaginal administration.