title: Bioavailability of oral micronized progesterone.
abstract: Progesterone (P) has not been administered orally because of reportedly poor bioavailability and a rapid clearance rate. Unfortunately, the synthetic derivatives, although orally active, have a number of disadvantages and fail to mimic natural P completely. To investigate the bioavailability and short-term toxicity of oral micronized P, a standardized dose of 200 mg of micronized P was administered to nine healthy postmenopausal women and one male subject. Serial determinations of serum P concentrations demonstrated rapid absorption of P. Peak concentrations of P rose from a negligible baseline level to 17.0 +/- 4.9 ng/ml at an average of 2.8 +/- 0.35 hours after administration. The peak concentrations of P were equivalent to those observed in the midluteal phase in normal control cycles (14.1 +/- 2.7 ng/ml). All subjects exhibited significant elevation of P over baseline levels that persisted for at least 6 hours after the single oral dose and returned to initial levels by 24 hours. There was no significant change in estradiol, follicle-stimulating hormone, luteinizing hormone, cortisol, aldosterone, lipids, or hepatic enzymes during the 24-hour study interval.
mesh_terms: D000284:Administration, Oral; D000328:Adult; D001682:Biological Availability; D002214:Capsules; D004958:Estradiol / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011374:Progesterone / Q000008:administration & dosage / Q000378:metabolism* / Q000633:toxicity; D013997:Time Factors
chemical_list: D002214:Capsules; D011374:Progesterone; D004958:Estradiol