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.
