Plasma Levels of 15(S)15-Methyl-pgf2α-methyl Ester Following Vaginal Administration for Induction of Abortion in Women

A single suppository containing 3.0 mg 15 (S)15-methyl-PGF2 alpha-methyl ester was administered vaginally in women to terminate mid-trimester pregnancy. Plasma levels of the drug (both methyl ester and free acid forms) were measured at different time intervals using deuterated carriers and gas chromatography-mass-spectrometry. 15(S)15-methyl PGF2 alpha (sum of methyl ester + free acid) was found to have a mean value of 1166 pg/ml plasma at 3 hrs after administration of the suppository. The mean levels were subsequently found to be maintained in the range of 1000 pg/ml. Preliminary studies showed that unlike the successfully aborted women, in those who did not abort within 30 hrs with this suppository, the plasma levels of the drug were not maintained for a sufficiently long time. The episodes of side effects, body surface area and the induction-abortion interval in relation to the plasma levels are discussed.