Micronised transdermal progesterone and endometrial response

Hormone Therapy and Breast Cancer: Emerging Steroid Receptor Mechanisms

Although hormone therapy is widely used by millions of women to relieve symptoms of menopause, it has been associated with several side-effects such as coronary heart disease, stroke and increased invasive breast cancer risk. These side-effects have caused many women to seek alternatives to conventional hormone therapy, including the controversial custom-compounded bioidentical hormone therapy suggested to not increase breast cancer risk. Historically estrogens and the estrogen receptor were considered the principal factors promoting breast cancer development and progression, however, a role for other members of the steroid receptor family in breast cancer pathogenesis is now evident, with emerging studies revealing an interplay between some steroid receptors. In this review, we discuss examples of hormone therapy used for the relief of menopausal symptoms, highlighting the distinction between conventional hormone therapy and custom-compounded bioidentical hormone therapy. Moreover, we highlight the fact that not all hormones have been evaluated for an association with increased breast cancer risk. We also summarize the current knowledge regarding the role of steroid receptors in mediating the carcinogenic effects of hormones used in menopausal hormone therapy, with special emphasis on the influence of the interplay or crosstalk between steroid receptors. Unraveling the intertwined nature of steroid hormone receptor signaling pathways in breast cancer biology is of utmost importance, considering that breast cancer is the most prevalent cancer among women worldwide. Moreover, understanding these mechanisms may reveal novel prevention or treatment options, and lead to the development of new hormone therapies that does not cause increased breast cancer risk.

Percutaneous progesterone delivery via cream or gel application in postmenopausal women: a randomized cross-over study of progesterone levels in serum, whole blood, saliva, and capillary blood

OBJECTIVE

This study aims to investigate the distribution of progesterone in venous whole blood, venous serum, fingertip capillary blood, and saliva after its topical application in both cream and gel formulations.

METHODS

Ten postmenopausal women were randomized to receive 80 mg of progesterone cream or gel applied daily for 14 days, crossing over after a 14-day washout. On the last day of each treatment period, venous blood, fingertip capillary blood, and saliva were sampled frequently for 24 hours after the final application.

RESULTS

After progesterone cream or gel application, serum progesterone levels rose gradually, reaching a peak at 9 and 8 hours, respectively; AUC(0-24) h was significantly higher with cream (12.39 vs 8.32 ng h mL(-1), P = 0.0391). Whole venous blood levels followed a pattern similar to that of serum but were considerably lower. Saliva progesterone showed a peak at 1 and 6 hours after cream and gel application, respectively, and C(max) was comparable with cream and gel. Saliva AUC(0-24) h was substantially higher than the corresponding area under the curve for serum or whole blood but did not differ significantly by delivery method (39.02 and 58.37 ng h mL(-1), P = 0.69). In capillary blood, C(max) was reached at the same time (8 h) and was similar with both formulations; AUC(0-24) h was also similar with both formulations (1,056 ng h mL(-1) for cream and 999 ng h mL(-1) for gel) but was dramatically higher than the corresponding areas under the curve for venous serum and whole blood.

CONCLUSIONS

After application of topical progesterone, saliva and capillary blood levels are approximately 10-fold and 100-fold greater, respectively, than those seen in serum or whole blood. High capillary blood and saliva levels indicate high absorption and transport of progesterone to tissues. Reliance on serum levels of progesterone for monitoring topical dose could lead to underestimation of tissue levels and consequent overdose.

Bioidentical hormones for maturing women

Despite medical progress, climacteric symptoms still exist. With the coming of age of the baby boomers, more and more women will be experiencing these symptoms which may be adversely affecting their lives. Mistrust of the medical community and prescription drugs has led many to search for that perfect product which will ameliorate their symptoms, with less or no risk. They are turning to compounded bioidentical hormones. However, the term is somewhat nebulous and ill defined. In this review, the term will be explained and evidence regarding efficacy and safety discussed.

Bioidentical Hormones for Menopausal Therapy

'Bioidentical hormones' is a term created by the lay media to refer to chemicals derived from plants that are modified to be structurally identical to endogenous human hormones. These compounds include estradiol, estrone, estriol, progesterone, testosterone and dehydroepiandrosterone when prescribed for menopausal women. Patients assume bioidentical hormones are natural and safer than synthetic hormones with regard to the risk of developing breast cancer and other diseases, but there is little evidence to support this belief. Proponents of this therapy also support the use of salivary hormone measurements to adjust doses of these hormones instead of adjustment based on improvement or lack of improvement in menopausal symptoms. In this review, the rationale behind the use of bioidentical hormones is discussed, along with the evidence supporting the use of compounded and FDA-approved bioidentical products.

Enhanced Oromucosal Delivery of Progesterone Via Hexosomes

PURPOSE

Formulation and characterization of progesterone loaded hexosomes employing a novel method for oromucosal delivery.

METHOD

Hexosomes were prepared employing a method in which ethanolic solution of lipid phase (monolein and oleic acid) was vortexed with aqueous phase (surfactant solution) and characterized for particle size, morphology and internal structure. FT-IR and confocal laser scanning microscopy (CLSM) were performed to investigate the possible mechanism and penetration pathway of hexosomes within the mucosa.

RESULTS

Hexosomes exhibited anisotropy, hexagonal shape and nanometric size (251.2+/-1.8 nm). Internal structure confirmed by X-ray diffraction peaks with spacing ratio of radical1:radical3:radical4 proved two-dimensional hexagonal arrangements. Entrapment efficiency of system was greater than 95%. In vitro release studies revealed an enhanced transmucosal flux (4.67+/-0.14 microg cm(-2) h(-1)) and decreased lag time (1.54 h) across albino rabbit mucosa. FT-IR and CLSM of treated mucosa shows lipid extraction phenomena as well as structural irregularities within intercellular lipids respectively. These irregularities can function as 'virtual channels' facilitating hexosome's penetration.

CONCLUSION

Developed hexosomes formulation exhibited high entrapment efficiency, high permeability and better stability on storage, thus proposing itself a novel carrier for enhanced oromucosal delivery of progesterone.

Effects of estradiol with oral or intravaginal progesterone on risk markers for breast cancer in a postmenopausal monkey model

OBJECTIVE

To evaluate the effects of oral estradiol given with either oral or intravaginal micronized progesterone (P4) on risk biomarkers for breast cancer in a postmenopausal monkey model.

DESIGN

This experiment was a two-way crossover study in which 20 ovariectomized adult female cynomolgus macaques were treated (in equivalent doses for women) with oral estradiol (1 mg/d) + oral micronized P4 (200 mg/d) or intravaginal P4 delivered by Silastic rings (6- to 10-mg/d release rate). Hormone treatments lasted 2 months and were separated by a 1-month washout period. The primary outcome measure was breast epithelial proliferation.

RESULTS

Serum P4 concentrations were significantly greater in subjects receiving oral P4 (10.9 ng/mL) compared with intravaginal P4 (3.8 ng/mL) at 2 to 3 hours after oral dosing (P<0.0001) but not at 24 to 28 hours after oral dosing (2.9 ng/mL for oral P4 vs 3.2 ng/mL for intravaginal P4 at 2 months, P=0.19). Serum estradiol concentrations were significantly lower after oral P4 than after intravaginal P4 (P<0.05 for all time points). Oral P4 resulted in significantly decreased body weight (-2.5%) compared with intravaginal P4 (+3.6%) (P=0.0001). Markers of breast proliferation, sex steroid receptor expression, and endometrial area did not differ significantly between oral P4 and intravaginal P4 treatments (P>0.1 for all).

CONCLUSIONS

Despite different pharmacodynamic profiles, oral and intravaginal P4 had similar effects on biomarkers in the postmenopausal breast.

Bioidentical hormones for menopausal hormone therapy: variation on a theme

BACKGROUND

Progesterone creams and natural or bioidentical compounded estrogen preparations are being promoted to consumers as safe alternatives to conventional menopausal hormone therapy and as health-promoting tonics. No reliable data support these claims.

SAFETY

Natural hormones, including estradiol, estriol, estrone, and progesterone, can be expected to have the same adverse event profile as conventional menopausal hormone regimens.

SALIVARY HORMONE TESTS

Salivary tests may be used to persuade asymptomatic consumers to use hormones (or symptomatic patients to use higher doses than those needed to mitigate symptoms), a practice that can be expected to result in adverse events.

Bleeding profiles and effects on the endometrium for women using a novel combination of transdermal oestradiol and natural progesterone cream as part of a continuous combined hormone replacement regime

OBJECTIVE

Many women are seeking alternatives to conventional forms of hormone replacement. This study evaluates the endometrial effects of natural progesterone cream used in conjunction with transdermal oestradiol.

DESIGN

Open plan study conducted over 48 weeks.

SETTING

Tertiary referral London teaching hospital.

POPULATION

Women at least two years postmenopausal.

METHODS

Women were recruited nationally. They applied 40 mg transdermal natural progesterone cream and 1 mg transdermal oestradiol daily.

MAIN OUTCOME MEASURES

Endometrial histology, assessed by pipelle endometrial biopsy, ultrasound assessment of endometrial thickness and bleeding diaries.

RESULTS

Fifty-four women were recruited of which 41 completed the study. Mean age was 57.4 years. Thirty-two percent of women had evidence of inadequate endometrial opposition (proliferative or hyperplastic) at the end of 48 weeks. At baseline, women had a mean endometrial thickness of 3.3 mm, which had significantly thickened to a mean of 5.3 mm by 24 weeks (P < 0.001). By 48 weeks, there was significantly greater increase in endometrial thickness from baseline in those women who displayed inadequate endometrial opposition, compared with those women who had adequate endometrial opposition (P= 0.004). At 24 weeks, 48% of women had remained entirely amenorrhoeic. By the end of the study, 35% of women had been entirely amenorrhoeic and 50% had had either no bleeding or spotting alone. The number of bleeding episodes did not reduce with time.

CONCLUSIONS

The dose of natural progesterone cream in this study was insufficient to fully attenuate the mitogenic effect of oestrogen on the endometrium. We would not recommend this combination of hormones to be used by postmenopausal women.

Percutaneous administration of progesterone: blood levels and endometrial protection

There is controversy about the beneficial effects of topical progesterone creams used by postmenopausal women. A major concern is that serum progesterone levels achieved with progesterone creams are too low to have a secretory effect on the endometrium. However, antiproliferative effects on the endometrium have been demonstrated with progesterone creams when circulating levels of progesterone are low. Thus, effects of topical progesterone creams on the endometrium should not be based on serum progesterone levels, but on histologic examination of the endometrium. Despite the low serum progesterone levels achieved with the creams, salivary progesterone levels are very high, indicating that progesterone levels in serum do not necessarily reflect those in tissues. The mechanism by which the serum progesterone levels remain low is not known. However, one explanation is that after absorption through the skin, the lipophilic ingredients of creams, including progesterone, may have a preference for saturating the fatty layer below the dermis. Because there appears to be rapid uptake and release of steroids by red blood cells passing through capillaries, these cells may play an important role in transporting progesterone to salivary glands and other tissues. In contrast to progesterone creams, progesterone gels are water-soluble and appear to enter the microcirculation rapidly, thus giving rise to elevated serum progesterone levels with progesterone doses comparable to those used in creams.

Distribution and metabolism of topically applied progesterone in a rat model

This study investigated the transdermal uptake and subsequent tissue distribution of [(3)H]progesterone applied in a commercially available progesterone cream in a rat model. Concentrations of lipid- and water-soluble metabolites of [(3)H]progesterone were also measured in plasma, urine and selected tissues (uterus, liver, kidney, salivary gland) 3 h after its topical application. Female rats were ovariectomized and adrenalectomized to remove all endogenous progesterone, and 4 weeks later were anaesthetized and 150 mg Pro-Feme cream (containing progesterone 3.2% w/w and 200 microCi [(3)H]progesterone) was applied to the abdominal skin. Six arterial blood samples were then obtained from a carotid cannula over the following 3h, and urine and selected tissue samples were collected after the final blood sample. Plasma progesterone increased progressively until 90 min, then remained relatively stable. Plasma levels of [(3H)]progesterone were high by the 15-min sample and increased only slightly thereafter. Water-soluble metabolites were detectable in plasma at 15 min, whereas lipid-soluble metabolites became apparent only by 60 min then increased progressively to 180 min. The tissue:plasma concentration ratio for [(3)H]progesterone exceeded 1 in all tissues, most notably in uterus (8.4) and lung (9.6), whereas urinary [(3)H]progesterone levels were only half those in plasma. Concentrations of lipid- and water-soluble progesterone metabolites were most prevalent in liver and kidney, and both reached very high concentrations in urine. These results demonstrate that topically applied progesterone is rapidly absorbed transdermally and that its patterns of distribution and metabolism are comparable to those previously reported for intravascularly administered progesterone.

Caution on the use of saliva measurements to monitor absorption of progesterone from transdermal creams in postmenopausal women

OBJECTIVES

To determine the levels of progesterone in plasma, red cells and saliva as well as pregnanediol-3-glucuronide excretion in postmenopausal women using transdermal progesterone creams.

METHODS

A double-blind placebo controlled study was carried out using 24 postmenopausal women. Creams (placebo, 20 or 40 mg progesterone/g) were applied twice daily for 3 weeks followed by 1 week without before a further 3-week treatment. Morning samples were collected at 0, 1, 3, 4, 7 and 8 weeks for analysis.

RESULTS

There were small increases in plasma progesterone levels and pregnanediol-3-glucuronide excretion compared to the placebo group and red cell progesterone levels never exceeded plasma levels during progesterone cream use. Saliva progesterone levels were very high and variable in the progesterone cream groups compared to the placebo group and presented a paradox to the usual relationship observed between plasma and saliva progesterone in premenopausal women.

CONCLUSION

The absorption of progesterone from transdermal creams is low and we caution against the use of saliva measurements to monitor progesterone absorption. The low systemic absorption of progesterone may not be due to peripheral conversion by 5 alpha-reductase(s). We also conclude that the low level of progesterone associated with red cells suggests they are not important in the delivery of progesterone to target tissues.

Salivary, but not serum or urinary levels of progesterone are elevated after topical application of progesterone cream to pre-and postmenopausal women

OBJECTIVE

The use of topically applied micronised ('natural') progesterone as a substitute for synthetic oestrogens and progestogen preparations is controversial. The aim of this study was to examine the changes in blood and salivary concentrations of progesterone following a single topical application of a progesterone cream.

PATIENTS AND MEASUREMENTS

We investigated six premenopausal women in the luteal phase and six postmenopausal women to determine the short-term changes in serum, urinary and salivary progesterone concentrations following a single 64 mg topical application of micronised progesterone.

RESULTS

Serum progesterone concentrations did not increase during the first 3 hours after application of progesterone cream, however, salivary values rose significantly in both premenopausal and postmenopausal women, consistent with the view that progesterone is absorbed and transported through the body. Salivary progesterone concentrations were significantly elevated above basal levels by 30-60 minutes and reached peak levels at 1-4 h, with mean levels approximately fivefold higher in premenopausal, than in menopausal women.

CONCLUSIONS

Salivary progesterone measurements confirm that topically applied progesterone is absorbed, despite the lack of change in serum progesterone concentrations. However, at the dose administered, serum progesterone levels do not reach those observed after oral or vaginally delivered progesterone preparations. Higher doses may be required to induce biological responses within the endometrium.