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

Lack of evidence that progesterone in ovulatory cycles causes breast cancer

Gompel A et al., 2023 · Climacteric

A recent Perspective article asserted that progesterone secretion during ovulatory cycles is the cause of breast cancer. However, we challenge most of the evidence developed in this publication. First, there is a lack of evidence that progesterone is mutagenic for breast cells. Cause of a cancer should mean initiation by mutation, as opposed to promotion. Second, subclinical ovulatory disturbances occur rather frequently in normal-length menstrual cycles. Third, the authors attribute a potential carcinogenic effect to progesterone secreted during menstrual cycles but not to progesterone during pregnancy. They did not discuss breast cancer evidence from progesterone/progestin therapeutics. They argue that in genetic primary amenorrhea, a hypothetic lower risk of breast cancer could be due to the lack of progesterone, despite the progesterone/progestin in hormone replacements these women receive. Fourth, they advocate a regulatory effect of progesterone on several genes potentially involved in cancer genesis. In particular, they attribute a lower risk of breast cancer in women with Mayer-Rokitansky-Küster-Hauser syndrome to a defect in the progesterone-stimulated Wnt4 gene. However, this defect is only present in a small subset. Thus, the postulated progesterone breast cancer risk is unconvincing, which we discuss point by point in this commentary.

Over-the-counter progesterone cream produces significant drug exposure compared to a food and drug administration-approved oral progesterone product

Hermann AC et al., 2005 · J Clin Pharmacol

Progesterone products are available in prescription form as well as over-the-counter (OTC) topical preparations sold for "cosmetic" uses. In a randomized study design, the authors compared the drug exposure from an OTC progesterone cream to a Food and Drug Administration-approved oral preparation at the labeled daily doses recommended for each product. Twelve healthy postmenopausal women received 200-mg oral progesterone capsules once daily for 12 days or progesterone cream 40 mg twice daily for 12 days. At steady state (day 12 of each phase), whole-blood samples were collected over 24 hours (oral progesterone) or 12 hours (topical progesterone) and assayed for total progesterone concentration. No significant differences were found in dose-normalized 24-hour progesterone exposure comparing the cream to oral capsules (median AUC(0-24) 12.5 ng x h/mL vs 10.5 ng x h/mL, respectively; P = .81). In light of the potential risks associated with long-term progesterone use, the authors question whether topical progesterone products should be available OTC.

Preeclampsia in multiple gestation: the role of assisted reproductive technologies

Lynch A et al., 2002 · Obstet Gynecol

To estimate the relationship of assisted reproductive technologies and ovulation-inducing drugs with preeclampsia in multiple gestations. This historical cohort study was conducted on 528 multiple gestations from a Colorado health maintenance organization. Using univariate and logistic regression analysis, we determined if women who conceived a multiple gestation as a result of assisted conception were at a greater risk of preeclampsia than those who conceived spontaneously. Between January 1994 and November 2000, there were 330 unassisted and 198 assisted multiple gestations. Sixty-nine multiple gestations followed assisted reproductive technologies (in vitro fertilization and gamete intrafallopian transfer). Human menopausal gonadotropins and clomiphene citrate were associated with 38 and 91 of the multiple gestations, respectively. Compared with unassisted multiple gestations, the relative risk of mild or severe preeclampsia among mothers who received assisted reproductive technologies was 2.7 (95% confidence interval [CI] 1.7, 4.7) and 4.8 (CI 1.9, 11.6), respectively. Adjusted for maternal age and parity, women who received assisted reproductive technologies were two times more likely to develop preeclampsia (odds ratio 2.1, CI 1.1, 4.1) compared with those who conceived spontaneously. The adjusted odds ratios of nulliparity and maternal age for preeclampsia were 2.1 (CI 1.3, 3.4) and 1.1 (CI 1, 1.1), respectively. Although the incidence of preeclampsia was greater in mothers who received clomiphene citrate and human menopausal gonadotropins, this association did not reach statistical significance at the P <.05 level. Women who conceive multiple gestations through assisted reproductive technologies have a 2.1-fold higher risk of preeclampsia than those who conceive spontaneously.

The dominant ovarian follicle

Hodgen GD, 1982 · Fertil Steril

Absorption of oral progesterone is influenced by vehicle and particle size

Hargrove JT et al., 1989 · Am J Obstet Gynecol

The oral route of progesterone administration has long been considered impractical because of poor absorption and short biologic half-life. Recent reports suggest that micronization of progesterone enhances absorption and increases serum and tissue levels of progesterone. This study checks serum progesterone levels before and 0.5, 1, 2, 3, 4, and 6 hours after oral administration of 200 mg of progesterone in seven subjects. Progesterone was plain milled, micronized, plain milled in oil, micronized in oil, or micronized in enteric-coated capsules. All patients exhibited a significant increase in serum progesterone levels after oral progesterone administration. Mean peak progesterone levels (30.3 +/- 7.0 ng/ml) (p less than 0.005) were achieved with micronized progesterone in oil at 2.0 +/- 0.3 (p less than 0.05) hours after administration. Four types of oral progesterone had equivalent mean peak elevations and mean times to peak: plain milled, 9.6 +/- 2.5 ng/ml at 4.0 +/- 0.5 hours; micronized 13.2 +/- 2.4 ng/ml at 3.2 +/- 0.4 hours; plain milled in oil, 11.3 +/- 3.0 ng/ml at 4.0 +/- 0.5 hours; and micronized in enteric-coated capsules, 11.2 +/- 3.0 ng/ml at 4.1 +/- 0.7 hours. Contrary to traditional teaching, these data show that significant serum progesterone levels can be achieved by oral administration. Absorption can be significantly improved by the physical characteristics of the progesterone and the vehicle used with oral administration.

Bioavailability of oral micronized progesterone

Maxson WS et al., 1985 · Fertil Steril

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.

Oral micronized progesterone. Bioavailability pharmacokinetics, pharmacological and therapeutic implications--a review

Sitruk-Ware R et al., 1987 · Contraception

Progesterone (P), the natural hormone, binds to its specific receptors to induce specific progestational effects. In addition to this binding, P is able to interfere with the binding sites of other steroids. Therefore the natural hormone exhibits an anti-estrogenic activity, and anti-androgenic activity and also exerts anti-mineralocorticoid effects. For a long time progesterone could not be used in clinical applications because of a rapid liver inactivation after oral administration. An oral micronized preparation of progesterone is now available which produces adequate plasma and tissue levels of progesterone. The preparation reproduces the anti-estrogenic effect of the natural hormone on the endometrium at the dose of 200 mg daily. It also reproduces the anti-mineralocorticoid effect and has no androgenic action. No side effects have been reported as far as lipids profile, coagulation factors and blood pressure are concerned. Therefore oral micronized progesterone appears suitable for hormonal replacement therapy in various areas, essentially postmenopause therapy, premenstrual syndrome, correction of irregular cycles and pregnancy maintenance.

Bioavailability of progesterone with different modes of administration

Chakmakjian ZH et al., 1987 · J Reprod Med

The bioavailability of micronized progesterone (P) was studied by measuring sequential serum P concentrations after a single bolus of 50-200 mg P given sublingually, orally (capsule and tablet), vaginally and rectally (suppositories) during the follicular phase in a group of normally menstruating women. When compared to other modes of P administration, the area under the curve during the first eight hours was twice as high with the rectal route. With 50 and 100 mg P given sublingually and 100 and 200 mg ingested as tablets, peak levels and area under the curve were twice as high with the higher dosage. The response was more sustained with the higher dosage. All subjects exhibited a significant increase in serum P levels over baseline that persisted for at least eight hours. P levels were still increased over baseline at 24 hours in all subjects after the administration of 100-mg vaginal and rectal suppositories and 200-mg tablets. These findings are in general agreement with previous reports showing that luteal phase serum P concentrations can be reached easily with non-parenteral modes of administering micronized P and that oral P administration could become an attractive alternative to the currently used oral mode of administering synthetic progestins.