The absorption of oral micronized progesterone: the effect of food, dose proportionality, and comparison with intramuscular progesterone

Fertil Steril. 1993 Jul;60(1):26-33.


Objectives: To examine the effects of food ingestion and administered dose on the absorption of oral micronized P (Utrogestan; Besins-Iscovesco, Paris, France) and to compare the bioavailability of intramuscular versus oral routes of administration.

Design: Prospective, randomized, open label crossover protocol with 7 days between dosages.

Setting: Academic institution.

Participants: Fifteen normal postmenopausal women.

Interventions: All subjects participated in three separate protocols: [1] micronized P (200 mg) or placebo under fasting or nonfasting conditions once daily for 5 days; [2] micronized P (100, 200, or 300 mg) once daily under fasting conditions for 5 days; and [3] micronized P (200 mg) or intramuscular P (50 mg in oil) administered once daily for 2 days.

Main outcome measures: Serum P concentrations were measured in all groups.

Results: Concomitant food ingestion increased the area under the serum P concentration versus time curve (AUC0 to 24) and the maximum serum P concentration (Cmax) without affecting time to maximum serum concentration (Tmax) (P < 0.05). Micronized P absorption and elimination were first-order processes and exhibited dose-independent pharmacokinetics between 100 and 300 mg. After intramuscular P, Cmax was higher and Tmax occurred later compared with the oral P preparation. Oral P had lower relative bioavailability (8.6%) than intramuscular P.

Conclusions: Absorption of micronized P was enhanced twofold in the presence of food. Both absorption and elimination were dose-independent, dose proportionality being confirmed. Bioavailability of the oral P was approximately 10% compared with intramuscular P.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adult
  • Aged
  • Biological Availability
  • Drug Compounding
  • Eating*
  • Fasting / metabolism
  • Female
  • Half-Life
  • Humans
  • Injections, Intramuscular
  • Intestinal Absorption*
  • Menopause / metabolism
  • Middle Aged
  • Progesterone / administration & dosage
  • Progesterone / blood
  • Progesterone / pharmacokinetics*
  • Prospective Studies


  • Progesterone