Morphometric study of the human endometrium following continuous exposure to levonorgestrel released from vaginal rings during 90 days

Intravaginal rings as delivery systems for microbicides and multipurpose prevention technologies

There is a renewed interest in delivering pharmaceutical products via intravaginal rings (IVRs). IVRs are flexible torus-shaped drug delivery systems that can be easily inserted and removed by the woman and that provide both sustained and controlled drug release, lasting for several weeks to several months. In terms of women's health care products, it has been established that IVRs effectively deliver contraceptive steroids and steroids for the treatment of postmenopausal vaginal atrophy. A novel application for IVRs is the delivery of antiretroviral drugs for the prevention of human immunodeficiency virus (HIV) genital infection. Microbicides are antiviral drugs delivered topically for HIV prevention. Recent reviews of microbicide IVRs have focused on technologies in development and optimizing ring design. IVRs have several advantages, including the ability to deliver sustained drug doses for long periods of time while bypassing first pass metabolism in the gut. IVRs are discreet, woman-controlled, and do not require a trained provider for placement or fitting. Previous data support that women and their male sexual partners find IVRs highly acceptable. Multipurpose prevention technology (MPT) products provide protection against unintended/mistimed pregnancy and reproductive tract infections, including HIV. Several MPT IVRs are currently in development. Early clinical testing of new microbicide and MPT IVRs will require a focus on safety, pharmacokinetics and pharmacodynamics. Specifically, IVRs will have to deliver tissue concentrations of drugs that are pharmacodynamically active, do not cause mucosal alterations or inflammation, and do not change the resident microbiota. The emergence of resistance to antiretrovirals will need to be investigated. IVRs should not disrupt intercourse or have high rates of expulsion. Herein, we reviewed the microbicide and MPT IVRs currently in development, with a focus on the clinical aspects of IVR assessment and the challenges facing microbicide and MPT IVR product development, clinical testing, and implementation. The information in this review was drawn from PubMed searches and a recent microbicide/MPT product development workshop organized by CONRAD.

Vaginal bleeding disturbances and implantable contraceptives

Implantable contraceptives allow safe and effective fertility regulation for up to 5 years. Currently available devices release low doses of progestogens. Disruption of vaginal bleeding patterns is almost inevitable, particularly during the initial months of use. Irregular and prolonged bleeding as well as amenorrhea are common. Irregular bleeding is unpopular with most women and unacceptable to some. This review describes the vaginal bleeding disturbances induced by modern implantable contraceptives and discusses the implications of these in terms of method use and discontinuations. The cause of the irregular bleeding is not fully understood, but recent evidence suggests that an increase in endometrial vascular fragility might precipitate vessel breakdown and, hence, breakthrough bleeding. This review discusses this evidence and outline the possible mechanisms underlying breakthrough bleeding associated with implantable contraceptives. In addition, therapies for bleeding disturbances are described and their efficacy reviewed.

Assessment of the oestrogenic activity of the contraceptive progestin levonorgestrel and its non-phenolic metabolites

Levonorgestrel (13beta-ethyl-17alpha-ethynyl-17beta-hydroxy-4-gonen-3-one), a potent contraceptive progestin stimulates growth and proliferation of cultured breast cancer cells through a receptor-mediated mechanism, even though levonorgestrel does not bind to the oestrogen receptor (ER). To assess whether the oestrogen-like effects induced by this synthetic progestin are exerted via its metabolic conversion products, we studied the binding affinity of three A-ring levonorgestrel derivatives to the ER and their capability to transactivate an oestrogen-dependent yeast system co-transfected with the human ER gene and oestrogen responsive elements fused to a beta-galactosidase reporter vector. The results demonstrated that the 3beta,5alpha reduced levonorgestrel derivative and to a lesser extent its 3alpha isomer interact with the oestrogen receptor, with a significantly lower relative binding affinity (2.4% and 0.4%, respectively) than that of oestradiol (100%), while levonorgestrel does not. Both levonorgestrel metabolites were able to activate, in a dose-dependent manner, the beta-galactosidase reporter gene in the yeast expression system, an effect that was precluded by a steroidal antioestrogen. The oestrogenic potency of levonorgestrel metabolites was significantly lower (750-fold) than that of oestradiol. Furthermore, high doses of 3beta,5alpha levonorgestrel (2.5 mg/day/6 days) induced an increase of oestrogen-dependent progestin receptor in the anterior pituitary of castrated rats. The overall data offer a plausible explanation for the weak oestrogenic effects induced by high, non-pharmacological doses of levonorgestrel.

Effect of a combined oral contraceptive containing 3 mg of drospirenone and 30 microg of ethinyl estradiol on the human endometrium

OBJECTIVE

To provide an in-depth assessment of the effects of the combined oral contraceptive containing 30 microg of ethinyl estradiol and 3 mg of drospirenone (Yasmin, Schering AG, Berlin) on the endometrium by means of endometrial morphometry in comparison to an untreated cycle.

DESIGN

The open, multicenter study consisted of one untreated precycle and 13 treatment cycles.

SETTING

Four gynecologic clinics in Belgium, The Netherlands, and Switzerland were involved.

PATIENT(S)

Forty women with a history of regular menstrual cycles.

INTERVENTION(S)

Before the commencement of the trial, 3 months without any hormonal intake was obligatory. The first endometrial sample was done in the untreated precycle, adjusted to the day of LH peak plus 5 to 6 days. During the medication phase, endometrial samples were taken at cycle 3, 6 and 13.

MAIN OUTCOME MEASURE(S)

Primary outcome measure of the study was the morphologic assessment of the endometrium with measures such as glandular diameter, glandular epithelial height, and number of vacuolated cells per 1,000 glandular cells. Furthermore, the endometrial thickness was measured by ultrasound.

RESULT(S)

After 13 cycles of medication use the endometrium had an atrophic appearance in 63% of the subjects. The size of the glands, the glandular epithelial height, and the number of glands per square millimeter were already significantly reduced after 3 months' use. Histological and ultrasonographical evaluation of the endometrium indicated a suppression of the proliferative activity of the endometrium.

CONCLUSION(S)

The combination of 30 microg of ethinyl estradiol with 3 mg of drospirenone induces changes of the endometrium that are comparable with other combined oral contraceptives and exhibits a marked antiproliferative effect on the endometrium. The medication was proven to be an effective oral contraceptive and revealed good cycle control characteristics.

Endometrial histomorphometry of trimegestone-based sequential hormone replacement therapy: a weighted comparison with the endometrium of the natural cycle

Histomorphometric changes in the endometrium were evaluated under the effect of a trimegestone-based sequential hormone replacement therapy (HRT) regimen, and the findings were compared to those in endometrium of the natural cycle. Endometrial samples were taken from postmenopausal women who completed a randomized, double blind, dose-ranging study of oral trimegestone (0.05, 0.1, 0.25 and 0.5 mg per day) from day 15 to day 28 with continuous micronized oestradiol 2 mg daily for six treatment cycles. The HRT-treated endometrium, irrespective of the dose, had a smaller mean total glandular area, smaller average glandular diameter, smaller mean total vascular space area and diameter than the luteal phase. Stromal cellularity was similar in the four dose groups. There were reduced glandular secretions in the endometrium from the high dose group. The relative weighting of these histological parameters was evaluated by linear discriminant analysis. The weighted values were dose independent, and may therefore represent either a specific effect of trimegestone, number of days administered, or both. We have constructed an equation to assign a value for a histological parameter which determines the position on linear discriminant functions. These assigned values can be used in other sequential HRT regimens to determine the relative influence of a given progestogen on endometrial morphology in relation to different phases of the natural cycle.

Effects of progestogens on human endometrium

The effect of progestogens on endometrium depends on the dosage, duration of exposure, the type of progestogen, and the presence or absence of estrogen. Mechanisms of progestogen action in endometrium are mainly expressed through the binding of hormone to specific nuclear receptors. Exogenous progestogens seem to influence the hypothalamic-pituitary-ovarian-endometrial axis differently in different individuals. Endogenous hormones resulting from ovarian secretion have effects on the endometrium independent of, and in combination with, exogenous progestogens. Endometrial morphological changes with progestogens vary from suppression of endometrial glandular growth, through stromal decidualization and leukocytic infiltration to glandular atrophy and stromal focal necrosis. In a minority of cases resulting from very prolonged treatment connective tissue fibers increase to some degree and may be accompanied by endometrial fibrosis and calcification. Clinical and histological data have demonstrated that all these changes, including fibrosis and calcification, return to normal in a short period after discontinuing treatment. Endometrial changes during progestogen therapy are often accompanied by leukocyte infiltration, especially when necrosis occurs. White blood cells constitute an important component of normal endometrium. The number and the type of leukocytes change during the normal menstrual cycle apparently related to circulating ovarian hormonal changes. Exogenous progestogens also influence white blood cells, by increasing total numbers and certain specific cell types. Changes in endometrial white blood cell function as a consequence of exogenous progestogens are unclear, but it is possible that the increase of leukocyte infiltration resulting from exogenous progestogens plays an important role in evoking progestational endometrial necrosis.

Endometrial morphometry in users of intrauterine contraceptive devices and women with ovulatory dysfunctional uterine bleeding: a comparison with normal endometrium

Copper-bearing intrauterine contraceptive devices (IUCD) are commonly associated with menorrhagia. They cause certain morphological changes in the endometrium. These have been extensively reported and the mechanisms of menorrhagia have been investigated in a number of studies. By contrast, ovulatory dysfunctional uterine bleeding has not been as widely studied and mechanisms of menorrhagia in these patients are still not well understood. In this study, we examined endometrial morphometry in a group of women using IUCD, a group of women with ovulatory dysfunctional bleeding, and a control group of women with entirely normal cycles. There was increased leukocytic infiltration of the endometrium in both groups of women with menorrhagia compared to control cases. In addition, IUCD use was associated with greater luteal phase glandular epithelial height, supporting the concept of a secretory function defect in glandular epithelium. Possible links are postulated between static morphometric observations and dynamic biochemical changes.

Studies on a vaginal ring releasing levonorgestrel at an initial rate of 27 micrograms/24 h when used alone or in combination with transdermal systems releasing estradiol

Vaginal rings releasing levonorgestrel (L-NOG) at an initial rate of 27 micrograms/24h were studied in a group of 24 normally menstruating women during three months (i.e., during three four-week segments). Each segment consisted of three weeks with the vaginal rings in situ followed by a treatment-free period of one week. The women were divided into three groups (8 subjects each). The first group received vaginal rings only, the second and third groups were treated, in addition, with transdermal systems (patches) releasing estradiol at a rate of 50 and 100 micrograms/24h, respectively. Peripheral blood samples were withdrawn three times weekly (Monday, Wednesday and Friday) during a pretreatment cycle and during the following three months of treatment. The levels of L-NOG, estradiol and progesterone were analyzed by radioimmunoassay techniques. In all subjects, endometrial biopsies were taken in a control cycle and during the last days with vaginal rings in situ in segments II and III. The treatment with estradiol did not significantly influence L-NOG levels. Considerable differences in the L-NOG levels between the subjects of the same group were observed. Fluctuation in ovarian reaction within groups was also large. Nevertheless, estradiol noticeably increased the proportion of anovulatory cycles; the total number of anovulatory segments was 5, 9 and 19 (out of 24) in the groups "No estradiol", "50 micrograms/24h estradiol" and "100 micrograms/24h estradiol", respectively. A morphometric study of the endometrium indicated a significant decrease in the diameter of glands. This change was due to L-NOG alone, but it seemed to be accentuated by the exogenous estradiol. The occurrence of glandular mitoses increased in both groups receiving estradiol in a dose-dependent manner, indicating an increased endometrial proliferation. The treatment with estradiol did not significantly alter the bleeding pattern.

Pharmacokinetic and pharmacodynamic effects of vaginal rings releasing levonorgestrel at a rate of 27 micrograms/24 hours: a pilot study

The pharmacokinetic and pharmacodynamic effects of vaginal rings releasing levonorgestrel (L-NOG) at an initial rate of 27 micrograms/24 h were studied in a group of 12 normally menstruating women during 90 days of continuous use (i.e., during three 30-day treatment segments). Blood samples were drawn immediately before insertion, 15 and 30 min, as well as 1, 2, 4, 8, 12 and 24 h after insertion of the rings, and thereafter three times weekly throughout the study for the analysis of L-NOG, estradiol, progesterone and sex hormone-binding globulin (SHBG). Endometrial biopsies were obtained for a morphometric analysis in a pre-treatment (control) cycle and in the 6th and 10th weeks of treatment. The peak of average L-NOG levels was reached within two hours after the insertion of rings. Until 24 h after insertion, the levels did not change significantly. Thereafter, a decrease at a rate of 0.2% per day was initiated. The L-NOG and SHBG levels were highly correlated. This was seen for both the pre-treatment SHBG vs L-NOG (r = 0.96) and the treatment SHBG vs L-NOG levels (r = 0.92). There was a significant (p < 0.001) decrease of SHBG levels due to treatment. During the total of 36 treatment segments, a normal ovarian function was seen in 47% of the segments. The women were anovulatory and had an inadequate lutal function in 28% and 25% of segments, respectively. No correlation between the L-NOG levels and ovarian reaction to treatment was found. The use of L-NOG induced significant changes in the endometrium; the number of glands/mm2 decreased after 6 (p < 0.02) and 10 weeks of use (p < 0.01). Also, the diameter of glands and the occurrence of vacuolated cells decreased significantly (p < 0.02 and p < 0.005, respectively). None of the endometrial parameters or dating was correlated with the ovarian reaction to treatment, indicating independent endometrial effects of L-NOG.

Cytokeratins 8, 18 and 19 in endometrial epithelial cells during the normal menstrual cycle and in women receiving Norplant

Cytokeratins 8, 18 and 19 are members of the cytoskeletal intermediate filament protein family. They are expressed in all simple epithelial tissues, including endometrium, and are recognised as dynamic structures that can be affected by numerous external factors. The Norplant system is a subdermal slow release levonorgestrel implant commonly used as a long-acting progestogen contraceptive. Norplant implants have been shown to have atrophic effects on endometrial epithelial and stromal cells, and cause a range of endometrial bleeding problems among users. The aim of this study is to describe changes in the immunohistochemical expression and distribution of cytokeratins 8, 18 and 19 in endometrial epithelial cells of Norplant implants users and normal menstrual cycle controls. Endometrial biopsies were collected from 65 control normal cycle women and 37 Norplant implants acceptors. The normal menstrual cycle was classified histologically into 9 stages; one menstrual, five proliferative and three secretory. Norplant implants bleeding patterns were categorised into 6 groups according to current World Health Organisation (WHO) definitions; amenorrhoea, frequent bleeding, infrequent bleeding, irregular bleeding, "normal" bleeding, and prolonged bleeding. The tissues were fixed in formalin, embedded in paraffin, and stained immunohistochemically. Semi-quantitative scoring of the staining intensity was performed. Apical versus basal intracellular cytokeratin distribution was also evaluated. The staining intensity was significantly stronger in control endometrial tissue compared to Norplant implants tissue. In control tissues, cytokeratins were predominantly located in the apical region of epithelial cells (52% of biopsies) and in Norplant implants tissues they were predominantly distributed equally between the apical and basal portions of epithelial cells (43% of biopsies). There was no particular cytokeratin distribution pattern associated with the different stages of normal cycle or the different Norplant implants bleeding patterns. It was concluded that long-term exposure to levonorgestrel significantly reduced the cytokeratin expression in endometrial epithelial cells (P < 0.001).

Lysosomal enzymes in the human endometrium: a biochemical study in untreated and levonorgestrel-treated women

The activities of four lysosomal enzymes, i.e. N-acetyl-beta-hexosaminidase, acid phosphatase, alpha-D-mannosidase and alpha-L-fucosidase have been measured in extracts of endometrial biopsies from untreated and levonorgestrel-treated women of fertile age. Values were compared with protein and DNA content, as well as with lactate dehydrogenase activity, used as reference constituents. In parallel, organ cultures were established from the same endometrial specimens and the release of lysosomal enzymes into the medium was followed. The human endometrium possesses a rich lysosomal equipment, comparable to that found in the human liver. In the untreated cycles, the activities of lysosomal enzymes show a coordinate response to the hormonal changes, decreasing by about 40% from the proliferative to the mid-late secretory phase. Long-term levonorgestrel treatment causes a marked cytoplasmic atrophy, as shown by decreased protein content and lactate dehydrogenase activity, whereas DNA content remains unchanged. In contrast, N-acetyl-beta-hexosaminidase, one of the most active lysosomal enzymes studied, shows a higher specific activity upon levonorgestrel. In both untreated and treated endometria, the organ cultures provide biochemical evidence for a higher release of N-acetyl-beta-hexosaminidase than of lactate dehydrogenase, indicating active secretion of the lysosomal enzyme. During levonorgestrel treatment, there was no correlation between clinically recognized spotting-bleeding patterns and lysosomal enzyme content in, or release from, the endometrium.