Sedative and hypnotic effects of oral administration of micronized progesterone may be mediated through its metabolites.

Progesterone and its metabolites were measured in serum extracts by radioimmunoassay and gas chromatography-mass spectrometry, respectively, after ingestion of micronized progesterone by eight postmenopausal women. One subject received 400 mg of micronized progesterone orally that induced a hypnotic state that lasted for approximately 2 hours. Blood samples were drawn periodically from all subjects for measurement of progesterone and its metabolites in serum. Levels of serum progesterone and its metabolites increased significantly from baseline values and reached a peak between 2 and 6 hours after oral progesterone administration. Significant quantities of five compounds (progesterone, 5 alpha-pregnan-3 alpha-ol-20-one, 5 beta-pregnan-3 alpha-ol-20-one, 5 beta-pregnan-3 alpha,20 beta-diol, and 5 beta-pregnan-3 alpha-ol-11,20-dione) that have been reported to possess anesthetic qualities were identified. The sedative and hypnotic effects of oral administration of progesterone may be mediated through those compounds.