title: Absorption and metabolism of oral progesterone when administered twice daily.
abstract: The absorption, metabolism, and clearance of progesterone (P) from the peripheral circulation were investigated in five postmenopausal women after oral administration of 100 mg at 9:00 A.M. and 200 mg at 9:00 P.M. for 5 consecutive days. Mean peak plasma concentrations of P were observed 2 hours after ingestion of both the 100 and 200 mg doses and were 22.7 and 47.7 nmol/l, respectively. Of the three metabolites studied, the plasma concentrations of pregnanediol-3 alpha-glucuronide were most raised by treatment; those of 17-hydroxyprogesterone were least raised. Increases in the plasma levels of 20 alpha-dihydroprogesterone were more sustained than those of P, and the plasma concentrations remained elevated at approximately 20 nmol/l for at least 12 hours after P administration. We conclude that administration of oral P 100 mg in the morning and 200 mg at night increases the circulating concentrations of P and the biologically active metabolite 20 alpha-dihydroprogesterone, and that the duration of these increases is sufficient to evoke progestational responses in responsive end-organs.
mesh_terms: D019326:17-alpha-Hydroxyprogesterone; D004092:20-alpha-Dihydroprogesterone / Q000378:metabolism; D000042:Absorption; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D006908:Hydroxyprogesterones / Q000378:metabolism; D008875:Middle Aged; D009934:Organization and Administration; D011276:Pregnanediol / Q000031:analogs & derivatives / Q000378:metabolism; D011374:Progesterone / Q000008:administration & dosage / Q000378:metabolism*; D013997:Time Factors
chemical_list: D006908:Hydroxyprogesterones; D004092:20-alpha-Dihydroprogesterone; C022270:pregnanediol-3 alpha-glucuronide; D011374:Progesterone; D019326:17-alpha-Hydroxyprogesterone; D011276:Pregnanediol