Plasma levels of antiprogestin RU 486 following oral administration to non-pregnant and early pregnant women

Second-Trimester Medical Abortion with Misoprostol Preceded by Two Sequential Doses of Mifepristone: An Observational Study

Introduction

Based upon the pharmacokinetics of mifepristone, we postulated that repeating a dose after its half-life period may potentiate its abortifacient effect.

Methods

We administered mifepristone (200 mg) on days one and two, and misoprostol on day three (200 or 400 μg, vaginally, six-hourly, upto three doses in 12 h) in 100 women (intervention group). We compared their outcome with that of another 100 women who received the one-dose mifepristone regimen (mifepristone on day one and misoprostol on day three) during the months immediately preceding the study period (historical controls).

Results

The mean age, parity and gestation (18 weeks) were similar in the two groups. On day three (before initiating misoprostol), cervix admitted one finger in significantly more women in the intervention group (36 versus 8% in historical controls; p = 0.001). All women aborted successfully in the two groups. The IAI of the intervention group was significantly shorter than the IAI of historical controls (10.45 vs 13.75 h; p = 0.013), and the misoprostol requirement was also significantly lower (mean 434 vs 500 μg among historical controls, p = 0.04).

Conclusions

Second-trimester medical abortion using two sequential doses of mifepristone followed by misoprostol reduced the IAI and misoprostol requirement without adding any extra days to the existing regimen. Further randomized studies can assess if the 'two-dose' mifepristone regimen is more efficient than the 'one-dose' regimen.

A method for overcoming plasma protein inhibition of tyrosine kinase inhibitors

Plasma protein binding reduces potency of staurosporine-derived tyrosine kinase inhibitors against Flt3-mutant AML. “Decoy” drugs interfering with the binding, including mifepristone, can be harnessed to restore the antileukemia activity.

FMS-like tyrosine kinase 3 (FLT3) is the most frequently mutated gene in acute myeloid leukemia and a target for tyrosine kinase inhibitors (TKI). FLT3 TKIs have yielded limited improvements to clinical outcomes. One reason for this is TKI inhibition by endogenous factors. We characterized plasma protein binding of FLT3 TKI, specifically staurosporine derivatives (STS-TKI) by alpha-1-acid glycoprotein (AGP), simulating its effects upon drug efficacy. Human AGP inhibits the antiproliferative activity of STS-TKI in FLT3/ITD-dependent cells, with IC₅₀ shifts higher than clinically achievable. This is not seen with nonhuman plasma. Mifepristone cotreatment, with its higher AGP affinity, improves TKI activity despite AGP, yielding IC₅₀s predicted to be clinically effective. In a mouse model of AGP drug inhibition, mifepristone restores midostaurin activity. This suggests combinatorial methods for overcoming plasma protein inhibition of existing TKIs for leukemia as well as providing a platform for investigating the drug–protein interaction space for developing more potent small-molecule agents.

Second trimester medical abortion in a primigravida with lupus nephritis and rapidly progressive renal failure: challenges and outcome

In the second trimester, medical abortion is preferred as it is less invasive, and the surgical method carries more risk. There is a paucity of published literature on medical abortion in women with renal failure requiring haemodialysis. We came across a woman who presented with rapidly progressive renal failure at 18 weeks of gestation and required therapeutic abortion. We are reporting the challenges, outcomes, and precautions to be taken while performing a medical abortion in such a case.

Selective Progesterone Receptor Modulators-Mechanisms and Therapeutic Utility

Selective progesterone receptor modulators (SPRMs) are a new class of compounds developed to target the progesterone receptor (PR) with a mix of agonist and antagonist properties. These compounds have been introduced for the treatment of several gynecological conditions based on the critical role of progesterone in reproduction and reproductive tissues. In patients with uterine fibroids, mifepristone and ulipristal acetate have consistently demonstrated efficacy, and vilaprisan is currently under investigation, while studies of asoprisnil and telapristone were halted for safety concerns. Mifepristone demonstrated utility for the management of endometriosis, while data are limited regarding the efficacy of asoprisnil, ulipristal acetate, telapristone, and vilaprisan for this condition. Currently, none of the SPRMs have shown therapeutic success in treating endometrial cancer. Multiple SPRMs have been assessed for efficacy in treating PR-positive recurrent breast cancer, with in vivo studies suggesting a benefit of mifepristone, and multiple in vitro models suggesting the efficacy of ulipristal acetate and telapristone. Mifepristone, ulipristal acetate, vilaprisan, and asoprisnil effectively treated heavy menstrual bleeding (HBM) in patients with uterine fibroids, but limited data exist regarding the efficacy of SPRMs for HMB outside this context. A notable class effect of SPRMs are benign, PR modulator-associated endometrial changes (PAECs) due to the actions of the compounds on the endometrium. Both mifepristone and ulipristal acetate are effective for emergency contraception, and mifepristone was approved by the US Food and Drug Administration (FDA) in 2012 for the treatment of Cushing's syndrome due to its additional antiglucocorticoid effect. Based on current evidence, SPRMs show considerable promise for treatment of several gynecologic conditions.

Effects of Ketoconazole on the Pharmacokinetics of Mifepristone, a Competitive Glucocorticoid Receptor Antagonist, in Healthy Men

Introduction

Mifepristone, a competitive glucocorticoid receptor antagonist approved for Cushing syndrome, and ketoconazole, an antifungal and steroidogenesis inhibitor, are both inhibitors of and substrates for cytochrome P450 (CYP3A4). This study evaluated the pharmacokinetic effects of concomitant ketoconazole, a strong CYP3A4 inhibitor, on mifepristone.

Methods

In an open-label, two-period, single-center study, healthy adult men received mifepristone 600 mg orally daily for 12 days (period 1) followed by mifepristone 600 mg daily plus ketoconazole 200 mg orally twice daily for 5 days (period 2). Serial pharmacokinetic blood samples were collected predose and over 24 h postdose on days 12 (period 1) and 17 (period 2). A cross-study comparison (using data on file) further examined whether systemic exposure to mifepristone plus ketoconazole exceeded the exposure following mifepristone 1200 mg orally administered for 7 days.

Results

Sixteen subjects were enrolled and 14 completed the study. Concomitant administration with ketoconazole increased the systemic exposure to mifepristone, based on geometric least squares mean ratios, by 28% for C_max and 38% for AUC_0–24. This increase was 85% and 87% of the exposure observed following mifepristone’s highest label dose of 1200 mg/day for C_max and AUC_0–24, respectively. Adverse events (AEs) were reported in 56.3% (9/16) of subjects during administration of mifepristone alone and in 57.1% (8/14) during combination with ketoconazole. No serious AEs were reported.

Conclusion

Systemic exposure to mifepristone increased following multiple doses of mifepristone 600 mg daily plus ketoconazole 200 mg twice daily. Little to no increase in AEs occurred. Dose adjustment of mifepristone may be needed when given with ketoconazole.

Funding

Corcept Therapeutics.

Efficacy of concurrent administration of mifepristone and misoprostol for termination of pregnancy

In this prospective randomized parallel group study, subjects with a pregnancy of less than 63 d were randomized to receive either (i) 200 mg oral mifepristone plus 400 μg misoprostol per vaginally concurrently (group A); (ii) or the administration of misoprostol after 48 h (group B). Transvaginal sonography was performed on the 14th day of misoprostol administration to confirm complete abortion. The primary outcome was to compare the rates of complete abortion in two groups. Secondary outcomes were to compare induction abortion interval, side effects and compliance. A total of 200 subjects included in the study were randomized into groups A and B (100 each). Both the groups were comparable for age, parity, gestational age and history of previous abortion. The complete expulsion rate in group A was 96% (95% confidence interval (CI) 95.1-98.2%) and group B was 95% (95% CI 93.0-96.8%) (p > 0.100). A gestational age of more than 56 d was found to predict failure of treatment in both groups. The adverse effect profile in the two groups was the same. Efficacy of concurrent mifepristone and misoprostol in combination is similar to that when misoprostol is given 48 h later (ctri.nic.in CTRI/2010/091/001422).

Concurrent Use of Mifepristone and Misoprostol for Early Medical Abortion

OBJECTIVE

This study was designed to evaluate the efficacy of using mifepristone and misoprostol concurrently for early medical abortion.

MATERIALS AND METHODS

A total of 90 women with undesired pregnancies <or= 49 days' gestation were enrolled. All women concurrently received oral mifepristone 200 mg and vaginal misoprostol 800 microg. Follow-up evaluation with transvaginal ultrasonography was performed 4 days and 2 weeks after treatment.

RESULTS

The complete abortion rate was 97.8% (88/90 women). The mean induction to abortion interval was 5.5 hours. The mean bleeding duration was 11.8 days. Patients found the side effects acceptable and reported a 91.1% (82 patients) satisfaction rate.

CONCLUSION

Concurrent administration of oral mifepristone and vaginal misoprostol is an efficacious regimen for medical abortion of pregnancies <or= 49 days of gestation.

Mid-trimester induced abortion: a review

Mid-trimester abortion constitutes 10-15% of all induced abortion. The aim of this article is to provide a review of the current literature of mid-trimester methods of abortion with respect to efficacy, side effects and acceptability. There have been continuing efforts to improve the abortion technology in terms of effectiveness, technical ease of performance, acceptability and reduction of side effects and complications. During the last decade, medical methods for mid-trimester induced abortion have shown a considerable development and have become safe and more accessible. The combination of mifepristone and misoprostol is now an established and highly effective method for termination of pregnancy (TOP). Advantages and disadvantages of medical versus surgical methods are discussed. Randomized studies are lacking, and more studies on pain treatment and the safety of any method used in patients with a previous uterine scar are debated, and data are scarce. Pain management in abortion requires special attention. This review highlights the need for randomized studies to set guidelines for mid-trimester abortion methods in terms of safety and acceptability as well as for better analgesic regimens.

Mifepristone dose in the regimen with misoprostol for medical abortion

Medical abortion with the antiprogesterone mifepristone followed by a prostaglandin is highly effective and widely used. The mifepristone dose registered is a single dose of 600 mg followed by a suitable prostaglandin analogue 36-48 h later. The 600-mg dose was chosen arbitrarily, and later studies have proven one third of this dose to be equally effective when combined with a prostaglandin analogue. This report reviews published data on the efficacy of mifepristone in different doses and demonstrates that there are no differences neither clinically nor in pharmacokinetics if the dose is reduced to 200 mg.

Review of medical abortion using mifepristone in combination with a prostaglandin analogue

Induced abortion is still a major health problem in the world and the most frequently performed intervention in obstetrics and gynecology with an estimated total of 46 million worldwide each year. Medical abortion with mifepristone and prostaglandin was first introduced in 1988 and is now approved in 31 countries. This combination of drugs has recently been included in the List of Essential Medicines by the World Health Organisation. The present review summarizes the development, physiology and the development of the currently used regimens.

The pharmacokinetics of mifepristone in humans reveal insights into differential mechanisms of antiprogestin action

The pharmacokinetics of mifepristone is characterized by rapid absorption, a long half-life of 25-30 h, and high micromolar serum concentrations following ingestion of doses of >/=100 mg of the drug. The serum transport protein-alpha 1-acid glycoprotein (AAG)-regulates the serum kinetics of mifepristone in man. Binding to AAG limits the tissue availability of mifepristone, explaining its low volume of distribution and low metabolic clearance rate of 0.55 L/kg per day. In addition, the similar serum levels of mifepristone following ingestion of single doses exceeding 100 mg can be explained by saturation of the binding capacity of serum AAG. Mifepristone is extensively metabolized by demethylation and hydroxylation, the initial metabolic steps being catalyzed by the cytochrome P-450 enzyme CYP3A4. The three most proximal metabolites, namely, monodemethylated, didemethylated and hydroxylated metabolites of mifepristone, all retain considerable affinity toward human progesterone and glucocorticoid receptors. Also, the serum levels of these three metabolites are in ranges similar to those of the parent mifepristone. Thus, the combined pool of mifepristone-plus its metabolites-seems to be responsible for the biological actions of mifepristone. Recent clinical studies on pregnancy termination and emergency contraception have focused on optimization of the dose of mifepristone. In these studies it has become apparent that the doses efficient for pregnancy termination differ from those needed in emergency contraception-mifepristone is effective in emergency contraception at a dose of 10 mg, which results in linear pharmacokinetics. However, the >/=200 mg doses of mifepristone needed for optimal abortifacient effects of mifepristone result in saturation of serum AAG and thus nonlinear pharmacokinetics. In view of the pharmacokinetic data, it may be speculated that dosing of mifepristone for pregnancy termination and for emergency contraception could be reduced to approximately 100 mg and 2-5 mg, respectively. It remains to be seen whether the newly synthesized, more selective antiprogestins will prove more efficacious in the clinical arena.

Mifepristone: bioavailability, pharmacokinetics and use-effectiveness

The potentiality of mifepristone as an abortifacient and contraceptive drug along with its pharmacokinetic parameters is reviewed. Mifepristone or RU486 acts as antagonist to progestational and glucocorticoid functions. It is an orally active compound with nearly 70% absorption rate but its bioavailability is reduced to around 40% because of the first-pass effect. Peak plasma concentrations of 1.9 +/- 0.8, 3.8 +/- 0.9 and 5.3 +/- 1.3 micromol/l are reached within 1-2 h after oral administration of 50, 200 and 600 mg mifepristone in women, respectively, and are maintained at relatively high level up to 48 or 72 h depending on the ingested dose. The plasma kinetics of mifepristone followed two-compartment open model with a mean alpha-half-life of 1.4h, volume of distribution 1.47 l/kg and beta-half-life of 20-30 h in most of the subjects studied. Clearance from the body was mainly through feces (83%). Biologically active mono-demethylated, di-demethylated and hydroxylated metabolites were found in plasma soon after oral administration of mifepristone. RU486 and its mono-demethylated metabolite bind to progesterone receptors with high affinity. Mifepristone-bound receptor dimers suppress transcription activation and thus, bring about anti-progestational activity that makes mifepristone a potential abortifacient and contraceptive agent. Clinical trials for termination of early pregnancy with 50-600 mg mifepristone plus a prostaglandin analogue achieved a success rate of 82-97%. However, abdominal pain, cramping, nausea, vomiting, bleeding and delay in onset of the next menstrual cycle were the side effects. Administration of 25 mg mifepristone twice 12h apart, as a post-coital contraceptive showed 100% contraceptive efficacy. A low dose of mifepristone which does not inhibit ovulation reduced fertility significantly by affecting endometrial milieu. These findings suggest that reduced dose(s) of mifepristone, 200 mg or less, may be used as a post-coital contraceptive and in combination with vaginal misoprostol for termination of early pregnancy with high efficacy and minimal or no side effects.

Mifepristone (RU486): a review

OBJECTIVE

To review the literature concerning the mechanism of action and pharmacodynamics of mifepristone (RU486), potential new uses of RU486, and its current use not only as an abortifacient but also as therapy for endometriosis, leiomyoma, breast cancer, and meningioma.

DATA IDENTIFICATION AND SELECTION

Studies that relate to RU486 were identified through a MEDLINE search.

CONCLUSION(S)

RU486 is an 11 beta-dimethyl-amino-phenyl derivative of norethindrone with a high affinity for P and glucocorticoid receptors. The receptor binding is not followed by transcription of P-dependent genes. Mifepristone effectively blocks P receptors in the placenta, resulting in the termination of pregnancy. In addition, it has been used in the treatment of leiomyomata, endometriosis, advanced breast cancer, and meningioma. It is a powerful tool to study the molecular action of P and in the future may be used as an estrogen-free contraceptive.

Determination of RU486 (mifepristone) in blood by radioreceptorassay; a pharmacokinetic study

A human progesterone receptor assay has been developed for the measurement of the biologically active molecular fraction of RU486 (RU486 binding equivalent) for studying its pharmacokinetic properties. Thirty-nine healthy pregnant volunteers with amenorrhoea of 49 days or less receiving a single oral dose of 200 mg, 400 mg or 600 mg RU486 orally in a single dose were involved in this study. Blood samples were collected within 48 hours for the analysis. It was found that the pharmacokinetics of the RU486 binding equivalent followed an open two-compartment model. The dose was rapidly absorbed and peak serum concentrations were measured within 1-2 hours after ingestion of the drug. The distribution was also rapid, but the elimination was slow, the elimination half-life ranging between 83 and 90 hours. Significant differences were found between the peak plasma values for the 200 mg and 600 mg doses (p < 0.05) and between the AUCs for the 200 mg and 600 mg doses (p < 0.01) and the 400 mg and 600 mg doses (p < 0.05). It can be concluded that this newly developed radioreceptor assay satisfies the requirements of radioligand binding techniques and can be used to determine the serum levels of RU486 and its metabolites, which are able to bind to human myometrial progesterone receptors. The pharmacokinetics for the RU486 binding equivalent is similar to that for RU486, with the exception of very slow elimination, which may originate from the measurement of the biologically active metabolites together with the parent compound.

The antiglucocorticoid action of mifepristone

Glucocorticoid hormones influence the physiological activity of almost all cell types in the mammal. This is accomplished via a soluble receptor that, in the presence of an appropriate steroid, modifies the activity of RNA polymerase by binding to the site where different factors assemble for the initiation of cell transcription. The development of antiglucocorticoids has permitted the molecular elucidation of a number of underlying events. Contrary to the classical view, it is now clear that the affinity, stability and activability of the glucocorticoid receptor in the presence of a steroid are cell- and/or tissue-dependent events. The antiglucocorticoid RU 38486 can even activate transcription by binding to sites distinct from those that process transactivation by the agonist. Furthermore, glucocorticoids can sometimes activate the mineralocorticoid receptor, whereas mineralocorticoids can bind the glucocorticoid receptor. Since mifepristone is devoid of adverse toxicity, it has been used for the paraclinical diagnosis of the hypothalamus-pituitary-adrenal axis in normal volunteers, subjects with disorders of the behaviour, and the treatment of Cushing's disease. However, the whole spectrum of cell-specific processes that are antagonized by RU 38486 suggests wide ranging possibilities in the eventual application of antigluco-corticoids.

Mifepristone (RU486) alone or in combination with a prostaglandin analogue for termination of early pregnancy: a review

The availability of a medical mode of termination of early pregnancy by the administration of RU486, an antiprogesterone alone, or in combination with one of the PG analogues significantly reduces the maternal morbidity and mortality associated with the classical surgical abortion. RU486 given alone in early pregnancy induces complete abortion in 60% to 85% of cases, and when combined with prostaglandin analogues, gemeprost or sulprostone, reaches a success rate of 95% to 99%. RU486 may also be of potential value in the medical treatment of ectopic pregnancy. Its use as a postcoital contraception is suggested, but further research is required to determine whether RU486 can be used on a once-a-month basis for contraception.

Pregnancy termination with mifepristone and gemeprost: a multicenter comparison between repeated doses and a single dose of mifepristone. World Health Organization

OBJECTIVE

To compare two regimens of mifepristone plus gemeprost for early pregnancy termination.

DESIGN

A prospective, randomized, multicenter trial.

SETTING

Ten gynecological services, mostly in academic hospitals.

PARTICIPANTS

Three hundred eighty-five healthy women up to 35 years of age with amenorrhea less than or equal to 49 days requesting pregnancy termination.

TREATMENT

Mifepristone, 25 mg five times at 12-hour intervals (n = 192) or 600 mg as a single dose (n = 193) followed by 1 mg gemeprost 60 hours after the start of mifepristone.

MAIN OUTCOME MEASURES

Pregnancy outcome, time of onset and duration of vaginal bleeding, subjective complaints, and hormone changes during treatment and 6-week follow-up.

RESULTS

Treatment outcome was identical in both groups with an overall complete abortion rate of 92.7% among the 385 women included in the analysis. The frequency of complaints, bleeding patterns, and changes in hemoglobin, beta-human chorionic gonadotropin, estradiol, and progesterone were also similar in both groups. Cortisol (at 12 and 36 hours after mifepristone) and prolactin (at 12 hours) were significantly higher in the single 600-mg dose group.

CONCLUSION

When used for early pregnancy termination with prostaglandin, a lower dose of mifepristone than the currently recommended single 600-mg dose may suffice.

Antiprogesterone RU 486--a drug for non-surgical abortion

RU 486 is the first steroidal antiprogesterone in clinical use. It acts by binding to progesterone receptor, thus blocking the effects of progesterone at the uterine level, and provoking endometrial necrosis and shedding. RU 486 can, therefore, be used to interrupt early human pregnancy. In pregnancies of up to 7-8 weeks duration, the rate of complete abortions with RU 486 has ranged from 50% to 90%. The success rate can, however, be augmented up to 95%-100% by combining RU 486 with a low dose prostaglandin. RU 486 induced abortion has been well tolerated by women and highly acceptable to them. The bleeding starts 2-3 days after RU 486 administration lasting for 12-14 days. Possible clinical uses of RU 486 include induction of menstruation, late post-coital contraception, induction of labour after intrauterine fetal death, preoperative cervical ripening and treatment of progesterone receptor positive mammary tumours. When administered in the follicular phase of the cycle, RU 486 inhibits follicular development. In addition, the antiglucocorticoid properties of RU 486 have been used in symptomatic treatment of hypercortisolemia of Cushings disease. The pharmacokinetics of RU 486 are characterised by high micromolar serum concentrations, long half-life of 26-48 hours and substantial metabolism after oral administration. Although effective and well tolerated, RU 486 has aroused great moral controversy, which is currently hampering further testing and distribution of the drug. So far RU 486 has been accepted for termination of pregnancy in France and in the Peoples Republic of China, to be used with prostaglandins and under strict medical surveillance.

Pharmacokinetics of the antiprogesterone RU 486 in women during multiple dose administration

Serum levels of RU 486 were measured by high performance liquid chromatography (HPLC) following oral intake of 12.5, 25, 50 and 100 mg twice daily (b.i.d.) for 4 days, 50 mg b.i.d. for 7 days, as well as a single dose of 200 mg of RU 486. The pharmacokinetics of RU 486 were not linear: when the daily dose of RU 486 was 100 mg or more, the serum levels were similar. The pharmacokinetic behaviour of RU 486 during the treatment period was similar between the study subjects, whereas the elimination phase pharmacokinetics showed wide individual variation. Also the mean elimination phase half-lifes (t 12) of RU 486 varied from 25.5 to 47.8 h in the groups of different regimen, yet the variation between different groups was not statistically significant. The areas under the concentration curves (AUC) were calculated. In the multiple dose study (mds) the AUC0----12h:s decreased when the administered dose of RU 486 was increased. The AUC0----12h seen after administration of 100 mg b.i.d. x 4d. (mean +/- SEM = 0.43 +/- 0.04 mumol/l x h/mg) was significantly (P less than 0.05) lower than the AUC0----12h:s obtained with administration of 12.5 mg b.i.d. x 4d. (1.49 +/- 0.37 mumol/l x h/mg), 25 mg b.i.d. x 4d. (1.09 +/- 0.15 mumol/l x h/mg), and 50 mg b.i.d. x 7d. (0.72 +/- 0.11 mumol/l x h/mg). The AUC0----infinity obtained by administration of a single dose of 200 mg of RU 486 (sds) was 0.67 +/- 0.21 mumol/l x h/mg. It is concluded that if multiple dose administration of RU 486 is preferred, daily administration of relatively small doses of RU 486 over several days seem to be advantageous.

Early abortion with a single dose of the antiprogestin RU-486

RU-486 is a synthetic progesterone antagonist that is abortifacient in early pregnancy. This trial evaluated the effectiveness and safety of a single 600 mg oral dose given to 50 healthy women less than or equal to 49 days from their last menstrual period. Efficacy was inversely related to the initial beta-subunit of human chorionic gonadotropin level, ranging from 100% at less than 5000 mIU/ml to 81% at greater than 20,000 mIU/ml (p less than 0.05). Uterine bleeding was the most serious side effect. However, the mean change in the hemoglobin value 14 days after treatment was -0.4 gm/dl, and no patient required blood transfusion. This regimen appears to be simple, effective, and safe.

Interception. III: Postcoital luteal contragestion by an antiprogestin (mifepristone, RU 486) in 62 women

The new antiprogestin mifepristone (RU 486) was studied as an emergency postcoital contragestive. An actual pregnancy rate of 1.6% was observed and was related to the actual conception rate. The follow-up rate was 100%. The patterns of onset and duration of the induced menstruation after mifepristone treatment are described. This method provides a good new interceptive technique when the time for use of postcoital steroids or for a postcoital IUD insertion has lapsed.