Endometrial bleeding during hormone therapy: The effect of progestogens

Comparison of estrogenic components used for hormonal contraception

Attempts have been made over the years to replace ethinyl estradiol (EE) in combined oral contraceptives (COCs) with the less potent natural estrogen estradiol (E2), or its prodrug, E2 valerate (E2V), to improve their safety and tolerability. Recently, a COC incorporating a novel weak natural estrogen, estetrol (E4), combined with drospirenone, has become available. We present a comparative analysis of the three prevailing estrogens used in COCs, focusing on their structure-function relationships, receptor-binding affinity, potency, metabolism, pharmacokinetic parameters, and pharmacodynamics. The binding affinity of EE to estrogen receptor (ER)α is twice that of E2, whereas its affinity for ERβ is about one-half that of E2. E4 has a lower binding affinity for the ERs than E2. The high potency of EE is notable in its dramatic increase in estrogen-sensitive hepatic globulins and coagulation factors. EE and E2 undergo extensive and comparable metabolism, while E4 produces only a very limited number of metabolites. E4 has the highest bioavailability among the three estrogens, with E2 having <5%. Studies demonstrate consistent ovulation inhibition, although a higher dose of E4 (15 mg) in COCs is required to achieve follicular suppression compared to E2 (1-3 mg) and EE (0.01-0.035 mg). E2 and E4 in COCs may be less stimulatory of coagulant proteins than EE. Studies with E2/dienogest suggest a comparable risk of venous thromboembolism to EE/levonorgestrel, while data assessing risk with an E4-based COC are insufficient. Nevertheless, the E4-based formulation shows promise as a potential alternative to EE and E2 due to its lower potency and possibly fewer side effects.

Effects of hormone therapy on the endometrium in postmenopausal women: a one year randomized trial of low dose oral estradiol in association with a levonorgestrel-releasing intrauterine system or drospirenone

OBJECTIVES: to compare the endometrial effects and uterine bleeding patterns associated with treatment using (1) levonorgestrel-releasing intrauterine system (LNG-IUS) and estradiol (1 mg/day, p.o.) or (2) orally administered drospirenone (2 mg/day) andestradiol (1 mg/day). METHODS: thirty-four patients (aged 52.53 ± 4.44 in the LNG-IUS group and 53.15 ± 4.018 in the DRSP group) were randomized. The severity of menopausal symptoms was evaluated using the Kupperman index every three months. Transvaginal ultrasound, hysteroscopy and histological evaluation were repeated after 12 months. During this period, patients kept menstrual calendars. All categorical variables were described as percentages. Variables were tested for normal distribution and Student's t test was applied for independent samples and ANOVA forrepeated measures when appropriate. Data were considered to be significant when p<0.05. RESULTS: slight vaginal bleeding was reported in the first month of treatment by 53.3% of patients from the LNG-IUS/estradiol group compared with 7.7% of patients from the drospirenone/estradiol group. There were no differences in endometrial thickness between the two groups throughout the study period. End-of-study histological findings showed atrophic endometrium in 53.3% of patients in the LNG-IUS/estradiol group compared with 76.9% of patients in the drospirenone/estradiol group. CONCLUSIONS: our results suggest good endometrial protection with both HT regimens.

Abnormal bleeding during menopause hormone therapy: insights for clinical management

OBJECTIVE

Our objective was to review the involved mechanisms and propose actions for controlling/treating abnormal uterine bleeding during climacteric hormone therapy.

METHODS

A systemic search of the databases SciELO, MEDLINE, and Pubmed was performed for identifying relevant publications on normal endometrial bleeding, abnormal uterine bleeding, and hormone therapy bleeding.

RESULTS

Before starting hormone therapy, it is essential to exclude any abnormal organic condition, identify women at higher risk for bleeding, and adapt the regimen to suit eachwoman's characteristics. Abnormal bleeding with progesterone/progestogen only, combined sequential, or combined continuous regimens may be corrected by changing the progestogen, adjusting the progestogen or estrogen/progestogen doses, or even switching the initial regimen to other formulation.

CONCLUSION

To diminish the occurrence of abnormal bleeding during hormone therapy (HT), it is important to tailor the regimen to the needs of individual women and identify those with higher risk of bleeding. The use of new agents as adjuvant therapies for decreasing abnormal bleeding in women on HT awaits future studies.

The immninent dawn of SPRMs in obstetrics and gynecology

Selective progesterone receptor modulators (SPRMs) have been developed since the late 70s when mifepristone was first described. They act through nuclear progesterone receptors and can have agonist or mixed agonist antagonist actions depending on the cell and tissue. Mifepristone has unique major antagonist properties allowing its use for pregnancy termination. Ulipristal acetate has been marketed in 2009 for emergency contraception and has been recently approved for preoperative myoma treatment. Further perspectives for SPRMs use include long term estrogen free contraception, endometriosis treatment. However long term applications will be possible only after confirmation of endometrial safety.

Do molecular signals from the conceptus influence endometrium decidualization in rodents?

A critical period in establishing pregnancy occurs after the onset of implantation but before placental development. Evidence strongly suggests that abnormalities occurring during this period can result in pregnancy termination or in pre-eclampsia; the latter may lead to small-for-gestational-weight offspring that are likely to be unhealthy. Clearly, events occurring in the endometrium during the implantation process are crucial for proper fetal development and for optimal offspring health. In several mammalian species bi-directional communication between the conceptus and endometrium during implantation is required for successful pregnancy. Although different implantation and placentation modes occur in different mammalian species, common aspects of this bi-directional signaling may exist. The molecular signals from the trophoblast cells of the conceptus, which direct endometrial changes during implantation progression, are well known in some nonrodent species. Currently, we know little about such signaling in rodents during implantation progression, when the endometrium undergoes decidualization. This review focuses on data that support the hypothesis that paracrine signals from the rodent conceptus influence decidualization. Where possible, these findings are compared and contrasted with information currently known in other species that exhibit different implantation modes.

Effects of antiprogestins on the uterus

Progesterone-receptor modulators (PRMs) are progesterone-receptor ligands that can exert agonistic, antagonistic or mixed agonist-antagonist effects depending on the cellular context. The mechanisms of action of these compounds are still incompletely understood. PRMs already have several applications in women's health such as emergency contraception, pregnancy termination, management of early fetal demise and cervical maturation. The main indications that will be developed in the future include dysfunctional bleeding and preoperative treatment of uterine myomas. Other future indications may include estrogen-free contraception, treatment of endometriosis and prevention and treatment of breast cancer. However, the available data from mid- to long-term continuous administration studies has raised the issue of endometrial safety. For this reason, long-term applications of PRMs are currently postponed, although windows of treatment with a short course of progestin therapy, or even by a short interruption of treatment, could improve endometrial aspects if needed.