Bioavailability of oral micronized progesterone

Area of Science:

• Endocrinology
• Pharmacology
• Reproductive Medicine

Background:

• Oral progesterone administration is limited by poor bioavailability and rapid clearance.
• Synthetic progesterone derivatives have disadvantages and do not fully mimic natural progesterone.

Purpose of the Study:

• To investigate the bioavailability and short-term toxicity of oral micronized progesterone.
• To assess the pharmacokinetic profile of a single oral dose of micronized progesterone.

Main Methods:

• A single oral dose of 200 mg micronized progesterone was administered to nine healthy postmenopausal women and one male subject.
• Serial serum progesterone concentrations were measured over 24 hours.
• Levels of estradiol, FSH, LH, cortisol, aldosterone, lipids, and hepatic enzymes were monitored.

Main Results:

• Rapid absorption of oral micronized progesterone was demonstrated.
• Peak serum progesterone concentrations averaged 17.0 +/- 4.9 ng/ml at 2.8 hours, comparable to natural midluteal phase levels.
• Elevated progesterone levels persisted for at least 6 hours, returning to baseline by 24 hours.
• No significant changes in other hormones, lipids, or hepatic enzymes were observed.

Conclusions:

• Oral micronized progesterone exhibits favorable bioavailability and a pharmacokinetic profile suitable for oral administration.
• A single 200 mg dose was well-tolerated with no significant short-term toxicity observed.
• Micronized progesterone represents a viable oral therapeutic option, potentially overcoming limitations of synthetic derivatives.