The effect of RU486 administered during the proliferative and secretory phase of the cycle on the bleeding pattern, hormonal parameters and the endometrium

Clinical Utility of Mifepristone: Apprising the Expanding Horizons

Mifepristone is a progesterone and glucocorticoid receptor antagonist. Medical abortion with mifepristone and prostaglandin has revolutionized the abortion process extending abortion care to the doors of females. From as low as 2 mg/day to doses extending to 600 mg, from daily dosing to single dosage treatment, mifepristone has a wide perspective in the treatment of various pathologies. Cervical dilatation and myometrial contractility have made the utility of mifepristone feasible for second-trimester termination of pregnancy and induction of labor awaiting Food and Drug Administration approvals. Its anti-progesterone action on the menstrual cycle has a new dimension of use as a contraceptive, as well as use as a menstruation inductive agent. Its role in endometriosis, ectopic pregnancy, and adenomyosis requires more intensive research. Apoptotic action of mifepristone, interference of heterotypic cell adhesion to the basement membrane, cell migration, growth inhibition of various cancer cell lines, decreased epidermal growth factor expression, suppression of invasive and metastatic cancer potential, increase in tumor necrosis factor, downregulation of cyclin-dependent kinase 2, B-cell lymphoma 2, and Nuclear factor kappa B have opened its potential to be explored as anti-cancer treatment and its effects on leiomyoma. The drug needs to be studied more for the prospectus of its anti-glucocorticoid actions in a wider dimension beyond its acquiescence for the treatment of Cushing syndrome.

Genetic predisposition for multiple myeloma

Multiple myeloma (MM) is the second most common blood malignancy. Epidemiological family studies going back to the 1920s have provided evidence for familial aggregation, suggesting a subset of cases have an inherited genetic background. Recently, studies aimed at explaining this phenomenon have begun to provide direct evidence for genetic predisposition to MM. Genome-wide association studies have identified common risk alleles at 24 independent loci. Sequencing studies of familial cases and kindreds have begun to identify promising candidate genes where variants with strong effects on MM risk might reside. Finally, functional studies are starting to give insight into how identified risk alleles promote the development of MM. Here, we review recent findings in MM predisposition field, and highlight open questions and future directions.

Effect of mifepristone on the transcriptomic signature of endometrial receptivity

STUDY QUESTION

How does a single dose of mifepristone on Day 2 after the LH peak (LH + 2) affect the endometrial receptivity transcriptome as assessed by the receptive signature established by the endometrial receptivity analysis (ERA)?

SUMMARY ANSWER

A single dose of mifepristone on day LH + 2 renders the endometrium non-receptive by altering the transcriptome associated with endometrial receptivity.

WHAT IS KNOWN ALREADY

Mifepristone is a progesterone receptor modulator that has been shown to alter endometrial receptivity. The ERA is a computational predictor that utilizes gene expression data of 248 genes from next generation sequencing to identify endometrial receptivity status.

STUDY DESIGN, SIZE, DURATION

Endometrial biopsies were collected on day LH + 7 from controls (n = 11) and from women treated with mifepristone (n = 7). For further comparative analysis, samples were also obtained from women in the proliferative phase (n = 7).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Mifepristone treatment consisted of 200 mg administered on day LH + 2. Endometrial biopsies were treated for RNA isolation and cDNA conversion and sequencing. Endometrial receptivity status was assessed by the ERA computational predictor. Differential gene expression between groups was also assessed. Ingenuity Pathway Analysis was used for network analysis. Validation of gene expression results was done by qPCR.

MAIN RESULTS AND THE ROLE OF CHANCE

Control samples were all staged around 'receptive' as would be clinically expected for LH + 7. Treatment samples were all staged as non-receptive (all but one was classified as 'proliferative' and the last as 'pre-receptive'). Differential gene expression analysis yielded 60 differentially expressed genes between the control and treatment groups. Bioinformatic pathway analysis for differential expression showed inactivation of the progesterone and glucocorticoid receptors, consistent with mifepristone action.

LIMITATIONS, REASONS FOR CAUTION

The primary limitations are the relative small number of subjects and the use of a limited gene panel.

WIDER IMPLICATIONS OF THE FINDINGS

This study sheds further light on the endometrial receptivity altering effects of mifepristone and on progesterone action. It further shows the capacity of the ERA to identify pharmacologically induced non-receptive endometrium, which expands its possible use clinically and in research.

STUDY FUNDING/COMPETING INTEREST(S)

C.v.G. and N.R.B. have no conflicts of interest. P.G.L. reports honorarium from University of HK/Shenzhen, other from NIF, India, outside the submitted work. K.G.D. reports consultancy for Bayer AG, Exelgyn, HRA-Pharma, Gedeon Richter, MSD, Mithra, Exeltis and Natural cycles, payment for lectures from Bayer AG, NSD, Ferring, HRA-Pharma, Exelgyn and Exeltis and clinical trials for Bayer AG, MSD, Exeltis, Mithra, HRA-Pharma and Sun Pharma. C.S. has a patent gene expression profile (ERA) issued to Igenomix and is scientific director of Igenomix S.L. M.R., R.N. and J.M.V. are employees of Igenomix S.L.

TRIAL REGISTRATION NUMBER

N/A.

Effects of a prolonged, 72 hours, interval between mifepristone and gemeprost in second trimester termination of pregnancy: a retrospective analysis

OBJECTIVE

To evaluate if the 72 hours interval between mifepristone and gemeprost has a similar efficacy compared to the 48 hours interval for second trimester termination of pregnancy

STUDY DESIGN

Two-hundred and fifteen consecutive pregnant women, admitted to our hospital, for second trimester TOP, were included in this retrospective analysis. Standard protocol was followed for all patients. On the first day of the procedure oral mifepristone 200 mg was administered. After 72 (group A, n = 78) or 48 hours (group B, n = 113) women were admitted for administration of gemeprost 1 mg pessary as per protocol. The induction to abortion time was defined as the interval between the insertion of the first gemeprost pessary and the expulsion of the fetus.

RESULTS

There are no significant differences in the number of pessaries in the two groups. The induction to abortion interval was longer in group A than in group B. Twenty-one women required surgical evacuation of the uterus for retained placenta or incomplete abortion without difference between groups.

CONCLUSION

A 48-hours interval between mifepristone and gemeprost leads to better results than a 72-hours interval, with a shorter abortion length and represents the elective method for second trimester TOP.

Medical methods for mid-trimester termination of pregnancy

BACKGROUND

With the improvement of ultrasound technology, the likelihood of detection of major fetal structural anomalies in mid-pregnancy has increased considerably. Upon the detection of serious anomalies, women typically are offered the option of pregnancy termination. Additionally, there are still many reasons other than fetal anomalies why women seek abortion in the mid-trimester.

OBJECTIVES

To compare different methods of second trimester medical termination of pregnancy for their efficacy and side-effects.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, Popline and reference lists of retrieved papers and other sources.

SELECTION CRITERIA

All randomised controlled trials (RCTs) examining medical regimens for termination of pregnancy of a singleton living fetus between 12-28 weeks' gestation were analysed. The outcome measures were the induction to abortion interval, abortion rate within 24 hours, need for surgical evacuation, blood loss, uterine rupture, pain, and side-effects.Trials including >20% fetal death, multiple pregnancies, previous uterine scars and regimens which involved cervical preparation were excluded.

DATA COLLECTION AND ANALYSIS

Two authors selected the trials and three authors extracted data.

MAIN RESULTS

Fourty RCTs were included, addressing various agents for pregnancy termination and methods of administration. When used alone, misoprostol was an effective inductive agent, though it appeared to be more effective in combination with mifepristone. However, the evidence from RCTs is limited.Misoprostol was preferably administered vaginally, although among multiparous women sublingual administration appeared equally effective. A range of doses of vaginally administered misoprostol has been used. No randomised trials comparing doses of misoprostol were identified; however low doses of misoprostol appear to be associated with fewer side-effects while moderate doses appear to be more efficient in completing abortion. Four RCTs showed that the induction to abortion interval with 3-hourly vaginal administration of prostaglandins is shorter than 6-hourly administration without an increase in side-effects.Many studies reported the need for surgical evacuation. Indications for surgical evacuation include retained products of the placenta and heavy vaginal bleeding. Fewer women required surgical evacuation when misoprostol was administrated vaginally compared with women receiving intra-amniotical PGF(2a) . Mild, self-limiting diarrhoea was more common among women who received misoprostol compared to other agents.

AUTHORS' CONCLUSIONS

Medical abortion in the second trimester using the combination of mifepristone and misoprostol appeared to have the highest efficacy and shortest abortion time interval. Where mifepristone is not available, misoprostol alone is a reasonable alternative. The optimal route for administering misoprostol is vaginally, preferably using tablets at 3-hourly intervals. Apart from pain, the side-effects of vaginal misoprostol are usually mild and self limiting. Conclusions from this review are limited by the gestational age ranges and variable medical regimens, including dosing, administrative routes and intervals of medication, of the included trials.

Effects of a preovulatory single low dose of mifepristone on ovarian function

OBJECTIVES

To investigate the effect of a single low dose of mifepristone on ovarian function, when administered in the preovulatory period.

METHODS

Healthy women with regular menstrual cycles were studied during two consecutive menstrual cycles. Either mifepristone or placebo was given in a randomized double-blind order when the leading follicle reached a diameter between 15 and 17 mm. Daily ultrasound and serum hormone measurements were obtained until follicular collapse. Statistical analysis was performed using Wilcoxon signed-rank test.

RESULTS

Eight women entered the study, although one woman had to be excluded afterwards from analysis because her LH surge had already appeared on the day of treatment. The LH surge was delayed from day 14 to 17 (P = 0.01). Mifepristone caused a 3-day delay in follicular collapse, occurring on day 16 in control cycles and on day 19 in mifepristone treatment cycles (P = 0.02). The median cycle length was 26 days in control cycles and 30 days in mifepristone treatment cycles (P = 0.03). Progesterone measurement 7 days after follicular collapse did not differ significantly between both cycles.

CONCLUSIONS

A single 10-mg dose of mifepristone administered during the preovulatory phase of the cycle delays the LH surge and postpones ovulation.

Antifertility effects of antigestogens

Since the discovery of the structure and function of steroids over 60 years ago, it has long been recognized that synthetic antagonists of the natural hormones would have potential therapeutic uses. Antagonists of mineralocorticoids, androgens and oestrogens, for example spironolactine, cyproterone, flutamide and tamoxifen, have already found a place in the management of hormone dependent conditions. In 1982, chemists at Roussel UCLAF announced that they had synthesized mifepristone (RU486) 17β-hydroxy-11(p-(dimethylamino)phenyl)-17-(1-propynyl) estra-411, 9-dien-3-one) a derivative of norethindrone which had potent antiprogestogenic as well as antiglucocorticoid activity. Although it was immediately realised that this compound would potentially have wide clinical application, its development in the last 10 years has been dominated by its abortifacient action. In the original clinical report by Herrman and colleagues it was shown that bleeding occurred when it was given to female volunteers in the second half of the menstrual cycle. In addition, complete abortion occurred in eight of 11 women who took the drug in the early weeks of pregnancy. These findings, which demonstrated that mifepristone could be used as the basis of a medical method of inducing abortion, were immediately made the focus of groups opposed to abortion on moral grounds. Experience over the last 10 years has confirmed the promise of these early studies and mifepristone, in combination with a suitable prostaglandin, is now licensed in France, UK and Sweden for use as a medical method of inducing abortion in early pregnancy.

Endometrial effects of a single early luteal dose of the selective progesterone receptor modulator CDB-2914

OBJECTIVE

To test potential contraceptive mechanisms of the selective P receptor modulator CDB-2914 in the early luteal phase.

DESIGN

Prospective randomized clinical trial.

SETTING

Clinical research center.

PATIENT(S)

Fifty-six women with regular cycles.

INTERVENTION(S)

Women received a single dose of CDB-2914 (10, 50, or 100 mg) or placebo given after ovulation and within 2 days of the LH surge. Four to 6 days later, a transvaginal ultrasound scan measured endometrial thickness, and an endometrial biopsy specimen was obtained.

MAIN OUTCOME MEASURE(S)

The endometrium was evaluated by thickness and by immunohistochemical analysis for P-dependent markers; safety laboratory tests were performed, and E(2) and P levels were obtained.

RESULT(S)

CDB-2914 caused a significant dose-dependent decrease in endometrial thickness, an increase in glandular P receptors, and a decrease in peripheral node addressins. Estradiol and P levels and menstrual cycle timing were not altered. No adverse effects were observed.

CONCLUSION(S)

The alteration in endometrial thickness and P-dependent markers of implantation in the absence of changes in hormone levels and cycle length suggests that CDB-2914 may have contraceptive properties.

Toward developing a once-a-month pill: a double-blind, randomized, controlled trial of the effect of three single doses of mifepristone given at midcycle on the pattern of menstrual bleeding

OBJECTIVE

To test the feasibility of timing the administration of mifepristone as a once-a-month contraceptive pill on the 12th day before the next menses, as calculated from the length of the previous menstrual cycles.

DESIGN

Double-blind, randomized, controlled trial.

SETTING

Five family planning centers across the world.

PATIENT(S)

Three hundred ninety-nine women attending family planning clinics.

INTERVENTION(S)

Randomized to receive 10, 25, or 200 mg of mifepristone or a placebo.

MAIN OUTCOME MEASURE(S)

Lengthening or shortening of the normal menstrual cycle length following administration of the drug by at least 5 days.

RESULT(S)

The menstrual period came within 5 days of the predicted date in 88% of women receiving the placebo, 84% of women receiving 10 mg, 72% of women receiving 25 mg of mifepristone, and only 48% of women treated with 200 mg of mifepristone. Increasing the dose of mifepristone was associated with an increased chance of having a delayed period (P<.001). Only 45% of women were in the peri-ovulatory phase of the cycle according to LH and P measurements on the day of drug administration. Women treated before ovulation were more likely to have delayed menses with all three doses of mifepristone.

CONCLUSION(S)

Because of the disruption in cycle length, it appears unlikely that mifepristone administered once a month, at a calendar-based time, would provide a reliable method of contraception.

Mifepristone for luteal phase contraception

The concept of luteal phase contraception and the use of mifepristone in clinical trials, which allows for testing of its validity, as well as clinical pharmacological research designed to understand its mode of action, are reviewed. Early luteal phase administration has a variety of morphological, physiological and biochemical effects on the endometrium that are likely to interfere with embryonic-endometrial interactions. In fact, specifically designed pilot clinical trials as well as data derived from emergency contraception studies indicate that early luteal phase administration of mifepristone is highly effective in preventing pregnancy, with minimal disturbance of hormonal parameters or menstrual cyclicity. Mid and late luteal phase administration of mifepristone at doses above 25 mg are highly effective in inducing endometrial bleeding in nonconceptional cycles. However, administration of mifepristone within the period between implantation and expected menses fails to induce bleeding in a significant proportion of cases, and furthermore the bleeding induced does not insure the termination of pregnancy. While the data suggest there is potential for a once-a-month contraceptive pill, it is likely that no molecule endowed with partial agonistic properties, like mifepristone, will completely and reliably suppress the essential functions of progesterone in order to achieve contraceptive efficacy comparable to that of modern contraceptive methods.

Summary of evidence and research needs on the use of mifepristone in fertility regulation: consensus from the conference

The conference on the use of mifepristone to reduce unwanted pregnancy, sponsored by the World Health Organization, Concept Foundation and the Rockefeller Foundation, took place in Bellagio, Italy, between 24 and 28 September 2001. The objective of the conference was to review the scientific information and to evaluate the use of mifepristone for emergency contraception, luteal contraception and menstrual induction. Mifepristone is highly effective for emergency contraception but its advantages and disadvantages in comparison with levonorgestrel need to be further studied. Data indicate that mifepristone alone or in combination with misoprostol has potential for occasional use for women seeking help following repeated unprotected intercourse and/or when the interval between intercourse and treatment is more then 120 h. Administration of mifepristone immediately after ovulation seems to be an effective contraceptive method. However, before it can be used commonly, there is a need for a simple and inexpensive method to identify the right time in the cycle. Once-a-month treatment with mifepristone and misoprostol at the expected time of menstruation is not a practical method due to bleeding irregularities and timing of treatment. Menstrual induction with mifepristone and a suitable prostaglandin analogue is highly effective. A randomized comparison with manual vacuum aspiration is, however, needed before it can be recommended for routine use.

Menstrual induction with mifepristone and misoprostol

Menstrual induction refers to early uterine evacuation without laboratory confirmation of pregnancy in women with delayed menses. Mechanical aspiration is the method used in many countries but, as suggested by a pilot study, mifepristone followed by a prostaglandin analogue could also be effective. We launched the present study to evaluate the efficacy and side effects of 150 mg of mifepristone, followed 2 days later by 0.4 mg misoprostol vaginally, for menstrual induction among women with a menstrual delay of up to 7 days. The outcome of treatment was uterine evacuation, which could mean menstruation or termination of early pregnancy. A total of 720 women were recruited. The mean delay of menstruation at recruitment was 4.9 (SD = 1.7) days. Retrospective analysis of human chorionic gonadotropin from serum samples taken at admission showed that 492 (68.3%) women were pregnant at admission, and 228 (31.7%) women had delayed menstruation without pregnancy. One nonpregnant woman was lost to follow-up. Bleeding was induced in 479 (97.4%) pregnant women and in 222 (97.8%) nonpregnant women. Among the pregnant women, 455 (92.5%) had complete abortion, 12 (2.4%) had incomplete abortion and pregnancy continued in 25 (5.1%) women, including one ectopic pregnancy. Side effects were mild and uncommon. We conclude that 95.8% of the women treated had the expected outcome. Further research is needed to compare the efficacy, safety and acceptability of the medical regimen to vacuum aspiration. A rather high continuing pregnancy rate in this study is a concern.

The possibility of using mifepristone for menstrual induction

Menstrual induction is a variant of suction aspiration that was originally defined to be performed in women with a menstrual delay of up to 2-3 weeks without knowing if the women is pregnant or not. Prerequisites for a pharmacological method for menstrual induction are a high efficacy to induce a bleeding in nonpregnant women and an expulsion of the pregnancy in pregnant women. Treatment with prostaglandins, specifically intramuscular sulprostone, can be as effective as suction aspiration for menstrual induction. However, the administration of prostaglandin in therapeutically effective doses was associated with a high frequency of gastrointestinal side effects and, to a lesser extent, of strong abdominal pain, which limited their routine use. More recent studies indicate that mifepristone in combination with either misoprostol or gemeprost is a more promising alternative. Further studies to identify the best treatment schedule are, however, needed, as is a randomized comparison with suction aspiration before a pharmaceutical method can be recommended.

Mechanisms of action of mifepristone when used for emergency contraception

An emergency contraceptive method is used after coitus but before pregnancy occurs. The use of emergency contraception is largely underutilized worldwide. Recently, treatment with 10 mg mifepristone as a single dose has emerged as one of the most effective hormonal methods for emergency contraception, with very low side effects. However, the mechanism of action of mifepristone in humans when used for contraceptive purposes and especially for emergency contraception remains largely unknown. The objective of this review is to summarize available data on the effect of mifepristone on female reproductive functions relevant to emergency use of the compound. Taken together, available data from studies in humans indicate that the contraceptive effect of mifepristone used as a single low dose for emergency contraception is mainly due to impairment of ovarian function, either by blocking or postponing the luteinizing hormone surge, rather than to inhibiting of implantation.

Effects of mifepristone on endometrial receptivity

At the development of receptivity the endometrium undergoes specific changes. Several factors have been suggested as markers of endometrial receptivity. A common feature for most of these factors is that they are directly, or indirectly, regulated by progesterone. The effect of various doses and regimens of mifepristone on endometrial development and markers of receptivity has been studied. Timed endometrial biopsies were assessed by immunhistochemistry, reverse transcriptase polymerase chain reaction (RT-PCR) and electron microscopy. In addition the contraceptive efficacy of these regimens was investigated. Administration of 200 mg of mifepristone immediately post ovulation has a pronounced effect on endometrial development and on suggested markers of receptivity. This regimen has been shown to be an effective contraceptive method. When 10 mg is given pre or post ovulation, only minor effects on the endometrium are observed. Our studies show that mifepristone, when administered in low doses that do not affect ovulation, significantly affects some of the studied markers of endometrial receptivity and reduces pregnancy rates; however, these activities are more pronounced with the higher dose, which is more effective. Our findings provide insight into the regulation of progesterone receptors of various suggested markers of endometrial receptivity and the possibility of using mifepristone for endometrial contraception.

A single dose of mifepristone (200 mg) in the immediate preovulatory phase offers contraceptive potential without cycle disruption

A single dose of mifepristone is an effective emergency contraceptive and has potential as a regular "once-a-month" pill. If given in the early luteal phase, the formation of a secretory endometrium is inhibited or delayed and implantation of the embryo prevented. We have explored the effect of giving the mifepristone just prior to ovulation on the ovarian and endometrial cycle. Seven women with regular menstrual cycles were studied during a control cycle and then in a second cycle when 200 mg mifepristone was given within 24 h of ovulation, i.e., when luteinizing hormone (LH) in serum was >15 IU/L and the dominant follicle was >18 mm. Ovulation was confirmed within 48 h by ultrasound in five of the seven women. The remaining two women had luteinized unruptured follicle. Following mifepristone, menses occurred after a normal luteal phase compared to control cycle (13.7 +/- 0.7 vs. 13.7 +/- 0.9 days). In all subjects the endometrium on LH + 6 in the treatment cycle showed no, or very little, secretory changes, suggesting it was unlikely that pregnancy would have occurred. We conclude that mifepristone could be given as a "once-a-month" contraceptive pill without causing significant disruption in the menstrual cycle in the majority of women for a 4-day period from just prior to ovulation until LH + 3.

Mifepristone-induced vaginal bleeding is associated with increased immunostaining for cyclooxygenase-2 and decrease in prostaglandin dehydrogenase in luteal phase endometrium

The mechanism of mifepristone-induced vaginal bleeding and endometrial shedding was investigated in 13 women who took 200 mg mifepristone in the midluteal phase on d 8 after the onset of the urinary LH surge (LH+8). Endometrial biopsies were collected, 6-24 h after mifepristone (group 1, n = 7) or 36-48 h after mifepristone (group 2, n = 6), and compared with those from a control group in the midluteal phase (n = 7). All women reported vaginal bleeding commencing 36-48 h after taking mifepristone. Treatment with mifepristone significantly reduced serum progesterone levels in all women, when compared with the controls (13.2 nM vs. 34.8 nM, P = 0.001). After mifepristone, a significant increase in cyclooxygenase-2 immunoreactivity was apparent at 36-48 h (P = 0.0018), whereas prostaglandin 15 dehydrogenase enzyme-positive immunostaining declined, to be virtually absent by 36-48 h in both glands and in stroma (P < 0.05). There was no change in intensity or distribution of staining for steroid receptors after mifepristone. The changes in immunostaining for cyclooxygenase-2 and prostaglandin 15 dehydrogenase strongly support the hypothesis that an increase in the local concentration of prostaglandins in the endometrium is involved in the mechanism of bleeding induced by mifepristone in the luteal phase.

Progesterone and ovulation

The role of progesterone (P) in the mechanism of ovulation is controversial at best. The contraceptive application of P was established in rodents in 1936 and with orally absorbed progestogenes was put to human use. There were hints on the proovulatory actions of P administered before the time of ovulation in rats by 1948. Similarly, in 1954 the observation of high P level in the preovulatory follicle pointed to a role in ovulation. Neither of these two observations was further investigated and the positive feedback effect of P exerted on gonadotropins was described in 1968. Still the positive feedback between P and gonadotropins were not recognized as a physiologic mechanism, much less utilized pharmacologically. The apparent contradiction between these two different actions of P continues upto now. The paper sets out to expose this controversy and tries to resolve it using extensive literary data and the author's experiences with synthetic progestogenes in contraception, in the treatment of infertility and with the antigestagen mifepristone in blocking ovulation. The precise mechanisms lying behind these applications are explored and discussed in detail. The putative role of oestradiol (E2) in the mechanism of eliciting the gonadotropin surge is extensively discussed but refuted as the ovulatory signal. The time sequence between the rise of P and gonadotropins contradicts the common wisdom of LH causing luteinization. The positive feedback effect of P on the E2 sensitized ovulatory axis on the hypothalamic and pituitary level is discussed and its local role in the mechanism of follicular rupture is also taken into account. The final proof seems to be the antiovulatory effect of mifepristone, which blocked both GnRH pulsatility, pituitary sensitivity to GnRH and follicular rupture in several experiments. Thus, the dogma of LH peak causing follicular rupture and subsequent luteinization seems questionable, the putative role of E2 to initiate the ovulatory cascade has to be discarded and P's role as a trigger of the physiological mechanisms leading to ovulation should be firmly recognized.

Mifepristone: a potential postcoital contraceptive

Mifepristone is an orally-active progesterone receptor antagonist. When a single dose of mifepristone is given in the mid- or late follicular phase, it may diminish or inhibit the luteinising hormone (LH) surge. In the early luteal phase, a single dose of mifepristone induces significant changes in the endometrium without affecting the hormonal levels or menstruation. When it is given in the mid-luteal phase, there will also be significant changes in the endometrium and some women may have two episodes of vaginal bleeding. A clinical trial suggests that a single dose of mifepristone in the early luteal phase may be an effective contraceptive agent but the lack of a cheap and easy method to identify the LH surge limits its clinical application. The administration of mifepristone alone or in combination with a prostaglandin does not appear to be an effective form of contraception. When used together with a prostaglandin, it may be an effective method for menstrual regulation but the cost and possible side effects of the prostaglandins limit its use. Mifepristone is a very effective method for emergency contraception. The incidence of side effects was also lower than that of the Yuzpe regimen. Lowering the dose of mifepristone from 600 to 10 mg does not decrease its efficacy but the incidence of delay in onset of the subsequent menses is reduced. Despite its efficacy, the reputation of mifepristone as an abortion pill may limit its access in many countries.

New contraceptive methods

As the number of abortion procedures performed each year reaches nearly 1 million, the incentive to decrease the incidence of unwanted pregnancy in the United States is high. Better education regarding women's health issues and enhanced contraceptive development are necessary to impact this long-standing problem. Several new contraceptive products are likely to become available in years to come to increase the number of choices that women and their health care providers have for pregnancy prevention. These products include long-acting implants, the levonorgestrel intrauterine device, patches, and the vaginal ring. This article surveys the near future of male and female contraception.

Contraceptive efficacy of daily administration of 0.5 mg mifepristone

The antiprogestin mifepristone has shown potential to be used as a contraceptive. If 200 mg mifepristone is administered immediately after ovulation, the endometrium shows sufficient impairment of secretory development to prevent implantation. Low daily doses of mifepristone have been shown to reduce several of the local factors regarded as crucial for implantation in human endometrium. To find out if this regimen is sufficient to prevent pregnancy, 32 women were recruited for a study where 0.5 mg mifepristone was administered daily. A total of 141 cycles were studied. Five pregnancies occurred, which was significantly less than if no contraceptive method had been used. However, the dose chosen did not seem sufficient to act as a contraceptive although it is probably not possible to increase the dose without disturbing ovulation and bleeding pattern.

Contraceptive use of antiprogestin

OBJECTIVES

To study the effect of antiprogestin on ovarian function and endometrial development during the menstrual cycle and the possibility of using these compounds for contraceptive purposes.

METHODS

Administration of different doses of the antiprogestin mifepristone during the menstrual cycle; intermittent measurements of luteinizing hormone, progestin and estrogen in blood and/or urine; endometrial morphology and concentration of markers for endometrial receptivity; efficacy trials of the contraceptive effect of mifepristone.

RESULTS

A high dose of mifepristone administered in the follicular phase will inhibit follicular development. If mifepristone is given immediately after ovulation, the secretory development of the endometrium and the expression of, for instance, leukemia inhibitory factor and integrins will be inhibited. Similar effects on the endometrium are obtained with small weekly doses (2.5 or 5.0 mg) or small daily doses (0.5 mg) of mifepristone, which do not inhibit ovulation. Once-monthly administration of 200 mg mifepristone on the day after ovulation, and emergency postcoital treatment, are highly effective methods for preventing pregnancy. Even 5 mg once weekly has a significant contraceptive effect.

CONCLUSIONS

The antiprogestin mifepristone has a number of effects during the menstrual cycle which makes the compound suitable for contraceptive use. Treatment after a single act of unprotected intercourse, and once-a-month treatment immediately after ovulation, have shown high contraceptive efficacy. A low-dose regimen which does not influence ovulation also has a contraceptive effect, but the efficacy needs to be improved before routine clinical use.

Contraceptive efficacy of low doses of mifepristone

OBJECTIVE

To determine whether a 5-mg dose of mifepristone is sufficient to prevent pregnancy.

DESIGN

Clinical study.

SETTING

Academic research center.

SUBJECT(S)

Healthy, fertile, sexually active female volunteers.

INTERVENTION

Volunteers received a 5-mg dose of mifepristone once weekly, starting on cycle day 2, for up to 6 months. This was their only contraceptive method.

MAIN OUTCOME MEASURE(S)

Number of pregnancies.

RESULT(S)

The treatment resulted in a significant decrease in pregnancy rate without affecting the menstrual cycle or causing disturbing side effects.

CONCLUSION(S)

A low dose of mifepristone, which does not inhibit ovulation, reduces fertility significantly by affecting the endometrium. However, the contraceptive effect needs to be improved for the drug to compete with other contraceptive methods.

Modern medical management of endometriosis

The modern medical management of endometriosis has changed considerably since the first attempts were made to control this disease hormonally over four decades ago. Currently, there are multiple choices for the clinician and patient, including oral contraceptives, danazol, GnRH agonist analogues, and gestrinone. Several advances have been made in the use of GnRH agonists in preventing some of the untoward effects of prolonged hypoestrogenism. These add-back regimens provide the best therapy available today for prolonged medical control of endometriotic symptoms. The antiprogesterones (RU-486) hold promise for the future, but are still in the investigational stage of development.

Anti-implantation activity of luteal phase mifepristone administration is not mimicked by prostaglandin synthesis inhibitor or prostaglandin analogue in the rhesus monkey

The use of mifepristone as an anti-implantation agent in the primate has been explored in the rhesus monkey with two specific aims: (i) to determine the contraceptive efficacy of very low-dose mifepristone administered on mated cycle days 16, 17, and 18; and (ii) to test the hypothesis that alteration in endometrial prostaglandin milieu by using either prostaglandin analogue or prostaglandin synthesis inhibitor can intervene the antifertility effect induced by mifepristone. Thirty female monkeys were randomly assigned to one of the six treatment groups. Five monkeys in the control group (group 1) were subjected to mating during cycle days 8-22. Four out of five monkeys became pregnant in the first mated cycle (80%) with detection of serum mCG by 12.7 +/- 1.5 days after ovulation. In group 2, 12 mated cycles were studied in five monkeys, mifepristone [RU486, 2 mg/day/animal, s.c. in 1 ml vehicle (1:4, benzyl benzoate:olive oil, v/v)] was given on cycle days 16, 17, and 18. In this group, no pregnancy was observed, thus providing complete pregnancy protection. Though there was an apparent extension of treatment cycle lengths in five cases with no incidence of inter-menstrual bleeding or spotting, there were no significant changes in serum estradiol (E) and progesterone (P). In group 3, four monkeys received prostaglandin (PG) synthesis inhibitor, diclofenac sodium (D, 25 mg/day/animal, i.m.) on cycle days 16, 17, and 18 in seven ovulatory menstrual cycles. Four of these cycles (57%) resulted in normal pregnancies; however, mCG detection (16.8 +/- 1.2 days after ovulation) was significantly (p < 0.05) delayed as compared to group 1. In group 4, four monkeys received 100 micrograms misoprostol (M), a PGE1 analogue, by gavage on mated cycle days 16, 17, and 18. Four pregnancies occurred in five treatment cycles (80%) with normal profiles of serum E and Pi mCG was first detected 13.2 +/- 1.7 days after ovulation. In group 5, seven monkeys received same dosages of RU486 and D on mated cycle days 16, 17, and 18. One hundred percent pregnancy protection was observed with luteal phase lengthening in eight treatment cycles but with unaltered E and P profiles. In group 6, five monkeys in nine treatment cycles received same dosages of RU486 and M on mated cycle days 16, 17, and 18. One pregnancy occurred; evaluation of E and P levels showed that the drug was given in the preovulatory period, which delayed ovulation and implantation, as mCG was detected 19 days post-ovulation. A delay in vaginal bleeding was observed in four treatment cycles with unaltered E and P profiles. Low-dose mifepristone appears to be a potential candidate for luteal phase and post-coital emergency contraception. However, the hypothesis that altered endometrial prostaglandin milieu may be responsible for mediating the anti-implantation effect of RU486 does not appear to be tenable based on our results in the rhesus monkey.

RU486 (mifepristone): mechanisms of action and clinical uses

RU486 (mifepristone) has proved to be a remarkably active antiprogesterone and antiglucocorticosteroid agent in human beings. The mechanism of action involves the intracellular receptors of the antagonized hormones (progesterone and glucocorticosteroids). At the molecular level, the most important features are high binding affinity to the receptor, interaction of the phenylaminodimethyl group in the 11 beta-position with a specific region of the receptor binding pocket, and RU486-induced transconformation differences in the ligand-binding domain. These particularities have consequences at different steps of the receptor function as compared with agonists. However, the reasoning cannot be limited to the RU486-receptor interaction, and, for instance, there is the possibility of a switch from antagonistic property to agonist activity, depending on the intervention of other signaling pathways. It would be desirable to have derivatives with only one of the two antagonistic properties (antiprogestin, antiglucocorticosteroid) in spite of similarities between steroid structures, receptors involved, and responsive machineries in target cells. Clinically, the RU486-plus-prostaglandin method is ready to be used on a large scale and is close to being as convenient and safe as any medical method of abortion may be. The early use of RU486 as a contragestive as soon as a woman fears a pregnancy she does not want will help to defuse the abortion issue. Research should now be conducted to define an efficient and convenient contraceptive method with RU486 or other antiprogestins. The usefulness of RU486 for obstetric indications, including facilitation of difficult delivery, has to be assessed rapidly. Gynecologic trials, particularly in leiomyomata, should be systemically continued. The very preliminary results obtained with tumors, including breast cancers, indicate that further studies are necessary.

Contraception with anti-progesterone

Anti-progesterones have potential as contraceptives, acting either by the inhibition of ovulation or the inhibition of endometrial development. Clinical studies have shown that once-a-month treatment with Mifepristone in the early luteal phase is an effective contraceptive method, and that emergency post-coital contraception with Mifepristone is at least as effective as other methods currently used. Recent studies indicate that the endometrium is more susceptible to Mifepristone than are the hypothalamic and pituitary regions, and it may therefore be possible to develop a new contraceptive method based on low daily or once-weekly doses of Mifepristone that does not influence ovarian function.

Treatment with a progesterone antagonist ZK 98.299 delays endometrial development without blocking ovulation in bonnet monkeys

The effects of an antiprogestin ZK 98.299 (onapristone) on serum levels of estradiol and progesterone, and on the endometrial morphology were studied in adult bonnet monkeys. Twelve animals having menstrual cycles of normal duration (24 to 30 days) were randomly distributed into 4 equal groups. The animals in Group 1 were treated (s.c.) with the vehicle (benzyl benzoate: castor oil, 1:10), and in Groups 2, 3 and 4 with 5 mg, 10 mg, or 20 mg ZK 98.299 once-a-week, respectively. Treatment was initiated on day 1 of the menstrual cycle and each animal in Groups 1, 2 and 3 was treated for two consecutive cycles. Since the treatment cycle length of animals in Group 4 was considerably prolonged, they were treated for one menstrual cycle only. Endometrial biopsy was taken around day 20 of the second treatment cycle of first three groups and around day 50 of the 4th group of animals. Treatment with vehicle or 5 mg ZK 98.299 had no significant effect on the menstrual cycle length. Treatment with 10 mg dose had no effect in two animals and prolonged the cycle length in one, whereas, further increase in the dose to 20 mg prolonged the cycle length in all the animals. The duration of menses was generally reduced. Treatment with vehicle or different doses of ZK 98.299 had no effect on ovulation. In animals treated with 5 or 10 mg dose, the pattern of mid cycle rise in serum estradiol levels and progesterone levels during the luteal phase of both treatment cycles were comparable to those of vehicle-treated animals and were suggestive of normal ovulatory cycles. On the other hand, in animals treated with the higher dose (20 mg/week), progesterone levels during the luteal phase were significantly reduced and were indicative of luteal insufficiency. The hormonal data during the treatment period of this group of animals was suggestive of two distinct ovarian cycles indicating that the menstrual bleeding during the treatment period was probably very scanty. Treatment with ZK 98.299 impaired the endometrial development in a dose-dependent manner. In vehicle-treated animals, the endometrium had large and tortous glands with secretions. Treatment with ZK 98.299 caused atrophic changes in the glands as well as in the stroma. The height of the epithelial cells was markedly decreased and they became small and inactive. This study, therefore, suggests that treatment with low doses of antiprogestin ZK 98.299 at weekly intervals does not block folliculogenesis or ovulation, but has an inhibitory effect on the endometrium.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of antihormones on endometrial receptors and protein secretion

The antiestrogen tamoxifen and the antiprogestin RU 486 both interact with respective hormones at the receptor level, RU 486 as a pure antagonist which inhibits endometrial development, the downregulation of estrogen and progesterone receptors and the production of endometrial protein, such as PP14, during the secretory phase of the menstrual cycle. Tamoxifen, on the other hand, has both agonistic and antagonistic action.

Mode of action of RU 486

RU 486 is a 19-norsteroid which has a specific high affinity binding to the progesterone and glucocorticoid receptor. It is generally accepted that RU 486 acts as a pure progesterone antagonist almost without agonistic activity. RU 486 acts mainly directly on the target organ, such as the endometrium, but also to some extent indirectly through an effect on the pituitary gonadotrophin secretion. The effect of RU 486 during the menstrual cycle is dependent on time of treatment. Treatment before ovulation will result in a prolongation of the proliferative phase of the menstrual cycle, while treatment during the mid- and late luteal phase will invariably induce bleeding, often followed by a second bleeding episode at the expected time of menstruation. The only treatment period which does not influence the menstrual cycle is treatment immediately following ovulation. Treatment during the proliferative phase has no effect on endometrial morphology but inhibits follicular development and delays oestrogen and LH surge. Treatment on the first days following ovulation has no effect on ovarian steroid concentration, but will significantly delay endometrial development, cause a change in the concentration of oestrogen and progesterone receptor concentration enzyme activity and production of substances thought to be progesterone dependent. The change in endometrial development is sufficient to prevent implantation. In mid- and late luteal phase, treatment with RU 486 will result in endometrial shedding in spite of normal progesterone levels. Post-ovulatory treatment with RU 486 will also significantly change uterine contractility. In early pregnancy, withdrawal of progesterone inhibition will result in uterine contractility and a significant increase in the sensitivity of the myometrium to prostaglandin.(ABSTRACT TRUNCATED AT 250 WORDS)

Interruption of endometrial maturation without hormonal changes by an antiprogesterone during the first half of luteal phase of the menstrual cycle: a contraceptive potential

OBJECTIVE

To examine hormonal and endometrial responses to intermittent low-dose RU486 administration in the luteal phase of the menstrual cycle.

DESIGN

Prospective open trial in which subjects serve as their own controls.

PATIENTS/PARTICIPANTS

Eight normal cycling women.

INTERVENTIONS

RU486 (10 mg, orally) was administered 5 and 8 days after urinary luteinizing hormone (LH) surge of treatment cycle.

MAIN OUTCOME MEASURES

Daily serum concentrations of LH, follicle-stimulating hormone, estradiol (E2), and progesterone (P) were determined in control, treatment, and recovery cycles (n = 5) or treatment and recovery cycles (n = 3). Changes in endometrial morphology and immunohistochemical staining for P receptor (PR) and E2 receptor (ER) were determined during control (or recovery) and treatment cycles.

RESULTS

Cycle length and hormonal patterns were unaltered after treatment with RU486. As demonstrated by reduced stromal edema and delayed glandular development, endometrial dyssynchrony occurred in all eight treatment cycles. In addition, seven of eight treatment cycle endometria demonstrated a decrease in PR staining without consistent change in ER staining.

CONCLUSIONS

Two low doses of RU486 given 72 hours apart during the luteal phase of the cycle disrupted ongoing endometrial maturation without altering the hormonal and time course of the menstrual cycle. This study provides a basis for the development of a novel form of luteal contraception.

Antiprogestin drugs: research and clinical use in Sweden

The Swedish experience indicates that the combination of RU 486 and vaginal or intramuscular administration of different prostaglandin analogues such as Cervagem, Sulprostone, and 15- methyl PGF2 alpha is a highly effective and safe non-surgical method to terminate early pregnancy. The combined treatment may also be used during the second trimester. In mid- and late second trimester abortion this procedure represents a simple, non-invasive, highly effective method. There are several possibilities by which RU 486 can be used as a contraceptive. We have shown that post-ovulatory administration of RU 486 will effectively inhibit implantation. If the preliminary results are confirmed, treatment with RU 486 once a month on day LH+2 may be an attractive alternative to present contraceptive technology.

RU486 and the early nineties

RU486 is a very powerful antisteroid hormone compound. Its antiprogestin activity particularly leads to clinical application in reproductive medicine. Its use for voluntary pregnancy interruption is only one aspect of its medical potentiality.

Modulatory actions of the new antiprogestins ZK 98.299 and ZK 98.734 and of RU 486 on luteinizing hormone secretion and progesterone effects in pituitary gonadotrophs

The effects of the antiprogestins (APs) ZK 98.299, ZK 98.734 and RU 486 on GnRH-stimulated LH secretion and their antagonistic activity on progesterone (P) actions were investigated in cultured pituitary cells from adult female Wistar rats. P (100 nM) was able to exert a facilitatory effect on GnRH (1 nM)-induced LH secretion after short-term (4 h) treatment of estradiol-primed (1 nM, 48 h) rat pituitary cells. When the APs (10 pM-10 microM) were introduced during the 4 h incubation period with P the facilitatory effect of P was totally abolished at concentrations greater than 10 nM (ZK 98.299, ZK 98.734) and greater than 1 nM (RU 486). Also the APs were shown to block the inhibitory action of P which occurs after long-term incubation of pituitary cells with this steroid. However at concentrations greater than 10 nM (ZK 98.734, RU 486) and greater than 100 nM (ZK 98.299) this antagonistic action of the APs was lost. To evaluate whether the APs have direct effects on GnRH-induced LH secretion in the absence of exogenous P pituitary cells cultivated for 48 h with or without 1 nM estradiol were incubated for 4 or 24 h with increasing concentrations of the APs (10 pM-10 microM). Four hour treatment of non-estradiol-primed cells with ZK 98.299 or ZK 98.734 was without any effect on the LH response to a 1 nM GnRH-stimulus. Only the highest concentration of RU 486 (10 microM) reduced the LH response. Twenty-four hour treatment of the cultures with the APs led to enhancement of GnRH-stimulated LH secretion by up to 113, 37 and 33% for ZK 98.734, ZK 98.299 and RU 486, respectively. When estradiol-primed cells were used for the same experiments we observed exclusively inhibitory effects on GnRH-induced LH secretion after 4 and 24 h treatment periods. It is concluded that these new APs are potent inhibitors of P-actions, but also per se they induce diverse effects on GnRH-stimulated LH secretion in cultured rat pituitary cells which have to be taken into account.

The antiprogesterone steroid, RU 486 (mifepristone)

RU 486 (Mifepristone) represents a major development in the field of hormone antagonists as the first effective antiprogestogen. A number of therapeutic roles for the drug are envisaged. It is already being used extensively around the world for the procurement of first trimester abortion--particularly in combination with prostaglandins. It also has been shown to be effective as a cervical ripening agent and for the induction of labour. Initial human studies have involved nonviable pregnancies and more work is needed in animal models before the drug can be deemed safe for use in viable human pregnancies in the third trimester.

Contragestion and other clinical applications of RU 486, an antiprogesterone at the receptor

RU 486, a steroid with high affinity for the progesterone receptor, is the first available active antiprogesterone. It has been used successfully as a medical alternative for early pregnancy interruption, and it also has other potential applications in medicine and for biochemical and pathophysiological endocrine research.