Gas chromatography/negative ion chemical ionization triple quadrupole mass spectrometric determination and pharmacokinetics of 11 alpha-hydroxy-9,15-dioxo-2,3,4,5,20-pentanor-19-carboxyprostan oic acid in plasma.

11 alpha-Hydroxy-9,15-dioxo-2,3,4,5,20-pentanor-19-carboxyprostanoic acid (PGE-M) was determined in plasma. Analysis was performed using an isotope dilution assay and gas chromatography/triple quadrupole mass spectrometry (GC/MS/MS). Basal levels of PGE-M were 64.05 +/- 34.17 pg/ml. After infusion of 120 micrograms prostaglandin E1 (PGE1) in six subjects in 15 min, maximum levels of PGE-M of 618.6 +/- 210.3 pg/ml were reached 20-45 min after the end of infusion. 3 h after the end of the infusion, plasma levels were close to the preinfusion levels. The pharmacokinetics of PGE-M in plasma were also determined. PGE-M has a half-life of 8.96 +/- 3.53 min for formation and 31.71 +/- 6.39 min for elimination. In addition to PGE-M, PGE1, 15-keto-PGE1 and PGE0 were also determined by GC/MS/MS.