Pharmacokinetics of rioprostil in human plasma as assayed by combined capillary gas chromatography-negative ion chemical ionization mass spectrometry.

To investigate the pharmacokinetics of rioprostil in man an assay is developed to analyse levels of rioprostil in plasma. After extraction and purification by solid-phase cartridges rioprostil is measured by negative ion chemical ionization mass spectrometry using a deuterated internal standard. The method is validated by a recovery experiment. Levels of rioprostil in the plasma of four volunteers following a single oral dose of 600 micrograms rioprostil are found as always below 100 pg/ml. The data presented here suggest that rioprostil is transformed rapidly in man to its more polar metabolites.