Bioavailability of oestradiol from the Alora TM (0.1 mg/day) oestradiol matrix transdermal delivery system compared with Estraderm (0.1 mg/day)

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.

A comparative characterization of estrogens used in hormone therapy via estrogen receptor (ER)-α and -β

Conventional hormone therapy (HT) containing estrogens such as ethinylestradiol (EE) have been associated with an increased risk of breast cancer and cardiovascular disease resulting in women seeking safer alternatives that are claimed to have fewer health risks. One such alternative gaining popularity, is custom-compounded bioidentical (b)HT formulations containing bioidentical estradiol (bE₂) and estriol (bE₃). However, the preparation of these custom-compounded estrogens is not regulated, and depending on the route of synthesis, steroid mixtures with differing activities may be produced. Thus, an investigation into the activities of estrogens prepared by custom-compounded pharmacies is warranted. The aim of this study was therefore to directly compare the pharmacological properties of bE₂ and bE₃ of unknown purity relative to commercially available, pure E₂, E₃ and estrone (E₁) standards as well as synthetic EE used in conventional HT via the human estrogen receptor (ER)-α and -β. We determined precise equilibrium dissociation constants (K_d or K_i values) and showed that bE₂ and bE₃ display similar binding affinities to the E₂ and E₃ standards, while EE had a higher affinity for ERα, and E₁ a lower affinity for ERβ. Furthermore, all the estrogens display similar agonist efficacies, but not potencies, for transactivation on a minimal ERE-containing promoter via the individual ER subtypes. Although E₂ and E₃ were equally efficacious and potent on the endogenous ERE-containing pS2 promoter in the MCF-7 BUS breast cancer cell line co-expressing ERα and ERβ, E₁ was less efficacious and potent than E₂. This study is the first to demonstrate that the bioidentical estrogens, commercially available estrogen standards and synthetic EE are full agonists for transrepression on both minimal and endogenous NFκB-containing promoters. Moreover, we showed that these estrogens all increase proliferation and anchorage-independent growth of MCF-7 BUS cells to a similar extent, suggesting that custom-compounded bHT may in fact not be a safer alternative to conventional HT. Furthermore, our results showing that E₃ and E₁ are not weak estrogens, and that E₃ does not antagonize the activity of E₂, suggest that the rationale behind the use of E₃ and E₁ in custom-compounded bHT formulations should be readdressed. Taken together, the results indicating that there is mostly no difference between the custom-compounded bioidentical estrogens, commercially available estrogen standards and synthetic EE, at concentrations reflecting serum levels in women using estrogen-containing HT, suggest that there is no clear advantage in choosing bHT above conventional HT.

Hormone replacement therapy use and plasma levels of sex hormones in the Norwegian Women and Cancer postgenome cohort - a cross-sectional analysis

Background

Hormone replacement therapy use (HRT) is associated with increased breast cancer risk. Our primary objective was to explore hormone levels in plasma according to HRT use, body mass index (BMI) and menopausal status. A secondary objective was to validate self-reported questionnaire information on menstruation and HRT use in the Norwegian Women and Cancer postgenome cohort (NOWAC).

Methods

We conducted a cross-sectional study of sex hormone levels among 445 women aged 48–62 who answered an eight-page questionnaire in 2004 and agreed to donate a blood sample. The samples were drawn at the women's local general physician's offices in the spring of 2005 and sent by mail to NOWAC, Tromsø, together with a two-page questionnaire. Plasma levels of sex hormones and Sex Hormone Binding Globulin (SHBG) were measured by immunometry. 20 samples were excluded, leaving 425 hormone measurements.

Results

20% of postmenopausal women were HRT users. The plasma levels of estradiol (E₂) increased with an increased E₂ dose, and use of systemic E₂-containing HRT suppressed the level of Follicle Stimulating Hormone (FSH). SHBG levels increased mainly among users of oral E₂ preparations. Vaginal E₂ application did not influence hormone levels. There was no difference in BMI between HRT users and non-users. Increased BMI was associated with increased E₂ and decreased FSH and SHBG levels among non-users. Menopausal status defined by the two-page questionnaire showed 92% sensitivity (95% CI 89–96%) and 73% specificity (95% CI 64–82%), while the eight-page questionnaire showed 88% sensitivity (95% CI 84–92%) and 87% specificity (95% CI 80–94%). Current HRT use showed 100% specificity and 88% of the HRT-users had plasma E₂ levels above the 95% CI of non-users.

Conclusion

Users of systemic E₂-containing HRT preparations have plasma E₂ and FSH levels comparable to premenopausal women. BMI has an influence on hormone levels among non-users. NOWAC questionnaires provide valid information on current HRT use and menopausal status among Norwegian women who are between 48 and 62 years old.

Transdermal oxybutynin for overactive bladder

Overactive bladder is commonly treated with oral anticholinergic drugs such as oxybutynin chloride. Although oral anticholinergic agents have been effective in controlling urinary urgency and frequency and in decreasing incontinence episodes, adverse events, particularly dry mouth, often cause patients to discontinue oral therapy and to endure incontinence. Oxybutynin can be delivered transcutaneously, maintaining the efficacy of oral oxybutynin while significantly minimizing the side effects (eg, dry mouth) that may complicate therapy. By avoiding hepatic and gastrointestinal metabolism of oxybutynin, less N-desethyloxybutynin is produced (this compound is deemed responsible for the anticholinergic side effects such as dry mouth). This novel oxybutynin formulation offers patients who have overactive bladder and urge urinary incontinence a well-tolerated option for managing the symptoms of overactive bladder.

Transdermal testosterone for women: a new physiological approach for androgen therapy

Transdermal testosterone patches and topically applied gels have become well accepted for the treatment of testosterone deficiency in men and are currently being developed in appropriate dosage strengths for androgen therapy in women. The furthest developed among these products is an investigational testosterone matrix patch which is now in phase III clinical trials for the treatment of sexual dysfunction in oophorectomized and naturally menopausal women. This review article discusses the biopharmaceutical rationale for the transdermal delivery of testosterone to women, illustrates and quantitatively analyzes the pharmacokinetics and metabolism of the testosterone matrix patch and a recently investigated testosterone gel, and summarizes the efficacy and safety data that have been reported in phase II studies of the testosterone matrix patch in surgically menopausal women with sexual dysfunction and HIV-infected women with the AIDS wasting syndrome. The different effects of oral and transdermal estrogen therapy (ET) on the concentrations of total and free testosterone attained with the testosterone matrix patch are contrasted. Although still in development, transdermal testosterone therapy appears to be a promising new approach for providing physiologically based androgen therapy to women.

Variability of serum estrogens among postmenopausal women treated with the same transdermal estrogen therapy and the effect on androgens and sex hormone binding globulin

OBJECTIVE

To examine the variability of serum estrogens in response to transdermal estrogen replacement therapy (ET), and to determine the effects on androgens and sex hormone binding globulin (SHBG).

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

Women's hospital.

PATIENT(S)

Two groups of postmenopausal women: [1] 21 women not on ET enrolled and 17 completed the study; [2] 19 women on continuous transdermal ET enrolled and 13 completed the study.

INTERVENTION(S)

Women not on ET were administered a placebo patch or a newly initiated estrogen patch, then crossed over to the alternate treatment. Serum samples were obtained at baseline and the subsequent 3 days from the placebo and new-patch groups and from a separate group of women receiving continuous estrogen patch treatment.

MAIN OUTCOME MEASURE(S)

Estradiol (E(2)), estrone, estrone sulfate, T, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), androstenedione, free androgen index, and SHBG.

RESULT(S)

There was considerable intrapatient and interpatient variability in the estrogen response to identical treatment doses, with E(2) values differing between women as much as 138 pg/mL and E(2) increases above baseline differing as much as 90 pg/mL. Continuous treatment increased SHBG and decreased androstenedione levels; however, levels of T, DHEA, DHEAS, and free androgen index did not change.

CONCLUSION(S)

There is great variability of estrogen in response to transdermal ET, but minimal effect on circulating androgens.

Effectiveness of Alora estradiol matrix transdermal delivery system in improving lumbar bone mineral density in healthy, postmenopausal women

OBJECTIVE

To determine the lowest effective dose of an estradiol (E ) matrix-type transdermal delivery system (EMTDS; Alora) for preventing bone loss in postmenopausal women.

DESIGN

This double-blind, double-dummy, randomized, placebo-controlled, multicenter study enrolled 355 nonosteoporotic postmenopausal women who had been hysterectomized with or without oophorectomy at least 12 months earlier. Participants were randomly assigned to one of three doses of the EMTDS (0.025, 0.05, or 0.075 mg/day) or placebo administered twice weekly. Lumbar bone mineral density (LBMD) was measured by dual-energy x-ray absorptiometry at screening and after 1 and 2 years of treatment. Safety was assessed at regularly scheduled visits.

RESULTS

EMTDS provided statistically significant and clinically meaningful changes in LBMD relative to placebo. At 2 years, LBMD declined from baseline by 0.59% in the placebo group, but it increased from baseline by 1.65% ( = 0.0065), 4.08% ( = 0.0001), and 4.82% ( = 0.0001) in the EMTDS 0.025, 0.05, and 0.075 mg/day groups, respectively. The corresponding responder rates (defined as no change or increase in LBMD at endpoint) were 39.7% for placebo, 59.6%, 79.3%, and 83.9% in the EMTDS 0.025, 0.05, and 0.075 mg/day groups, respectively. Mean serum E concentrations were proportional to the dose of the E transdermal system and did not accumulate over the course of the study. Adverse events were generally comparable across treatment groups, with the majority being mild or moderate in severity and unrelated to study medication. Mammogram findings and other safety assessments were also comparable across groups and did not reveal any safety concerns with 2-y transdermal E treatment.

CONCLUSIONS

The EMTDS (Alora) administered twice weekly improves lumbar bone mineral density in healthy postmenopausal women, with the benefit of treatment evident by 1 year. The lowest effective dose is 0.025 mg/day.

Application and maintenance habits do make a difference in adhesion of Alora transdermal systems

OBJECTIVES

To explore and evaluate Alora placebo patch application and maintenance habits of women in order to identify the factors that influence adhesion success.

METHODS

This single-center, open-label, placebo, randomized, multiple-application, parallel-group study involved 99 healthy naïve users of transdermal patches. Participants applied and wore an Alora placebo patch for ten consecutive applications of approximately 3.5 days each and evaluated adhesion of the patches twice-daily. Three subgroups comprising participants achieving low, moderate or high adhesion success took part in focus groups to discuss their wear habits, practices and attitudes regarding transdermal patches.

RESULTS

There was a significant behavioral component involved in patch adhesion. The habits, practices and attitudes of high achievers were clearly different from the other two subgroups. The three most important issues identified to improve adhesion were: mastering the removal of the patch liner, identifying the best site of application, and developing and implementing techniques to maintain patch adhesion. The Alora placebo patch was well tolerated throughout the study.

CONCLUSION

The data showed that there is a learning curve involved in achieving maximal adhesion with a transdermal patch. During the study, a novel patch application method ('press, fold and slide') was demonstrated for the participants. This method was very well received by all participants and was more easily executed than the previous method. An adaptation of this method was incorporated into the Alora patient information leaflet, together with several other changes to help improve adhesion success.

Significant differences in estradiol bioavailability from two similarly labelled estradiol matrix transdermal systems

OBJECTIVE

To compare the bioavailabilities of estradiol delivered by two transdermal estradiol matrix systems; Alora and Evorel.

STUDY DESIGN

A single-center, open-label, randomized, two-period cross-over study in 33 postmenopausal women. The subjects received two successive 84-h applications of either Alora or Evorel (each labelled to deliver 50 micrograms/day 17 beta-estradiol) in a randomized sequence. Serial serum samples, collected over the 84-h period following the application of the second patch, were analyzed for estradiol using a validated radioimmunoassay method.

RESULTS

The fluctuation index produced by Evorel was significantly higher than that produced by Alora (Evorel, 135%; Alora, 76%; p < 0.0005). In addition, the estradiol baseline-corrected area under the curve for Evorel was significantly lower than that for Alora (Alora, 2871.8 pg h/ml; Evorel, 1870.6 pg h/ml; p < 0.0005). Both patches were found to be generally well tolerated.

CONCLUSION

Alora delivered a higher, more consistent concentration of estradiol into the systemic circulation over the entire dosing interval than did Everol. Although the full clinical significance of these findings is currently unknown, this study demonstrates that there are significant differences in estradiol delivery from these two products, although they are labelled with the same nominal delivery rate.