Chemical formula: C₂₁H₃₀O₂ Molecular mass: 314.462 g/mol PubChem compound: 5994
Progesterone is a naturally occurring steroid that is secreted by the ovary, placenta, and adrenal gland. In the presence of adequate estrogen, progesterone transforms a proliferative endometrium into a secretory endometrium. Progesterone is necessary to increase endometrial receptivity for implantation of an embryo. Once an embryo is implanted, progesterone acts to maintain the pregnancy.
Progesterone is a naturally occurring steroid that is secreted by the ovary, placenta, and adrenal gland.
Micronised progesterone is absorbed by the digestive tract. Pharmacokinetic studies conducted in healthy volunteers have shown that after oral administration of 2 capsules (200mg), plasma progesterone levels increased to reach the Cmax of 13.8ng/ml +/- 2.9ng/ml in 2.2 +/- 1.4 hours. The elimination half-life observed was 16.8 +/- 2.3 hours.
Progesterone serum concentrations increased following the administration of the progesterone vaginal tablets in 12 healthy premenopausal females. On day 1 of treatment, the mean Cmax 19.8 ± 2.9 ng/mL with a Tmax of 17.3 ± 3.0 hours after administration of progesterone three times daily 8 hours apart.
On multiple dosing, steady state concentrations were attained within approximately 1 day after initiation of treatment with progesterone. Trough values of 10.9 ± 2.7 ng/mL were observed with an AUC0-24 of 436 ± 43 ng*hr/mL on Day 5.
The progesterone vaginal gel is based on a polycarbophil delivery system which attaches to the vaginal mucosa and provides a prolonged release of progesterone for at least three days.
Progesterone is approximately 96%-99% bound to serum proteins, primarily to serum albumin (50%-54%) and transcortin (43%-48%).
Urinary elimination is observed for 95% in the form of glycuroconjugated metabolites, mainly 3α, 5 β–pregnanediol (pregnandiol).
Progesterone is metabolised primarily by the liver. The main plasma metabolites are 20 α hydroxy- ∆ 4 α-prenolone and 5 α-dihydroprogesterone. Some progesterone metabolites are excreted in the bile and these may be deconjugated and further metabolised in the gut via reduction, dehydroxylation and epimerisation. The main plasma and urinary metabolites are similar to those found during the physiological secretion of the corpus luteum.
The pharmacokinetics of micronized progesterone is independent of the dose administered. Although there were some inter-individuals variations, the same individual pharmacokinetic characteristics were maintained over several months permitting appropriate individual adaptation of the posology and indicating predictable responses to the drug.
As per adults above.
Nonclinical data revealed no special hazard for humans based on conventional studies of safety pharmacology, repeated dose toxicity, genotoxicity, carcinogenic potential, toxicity to reproduction and development.
In rabbits, progesterone was an eye irritant categorised class IV (minimal effects clearing in less than 24 hours), but not a dermal irritant. A moderate vaginal irritation was found in rabbits after application of 2.0 ml/day of 8% gel for 5 days.
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