Radioimmunoassay of serum medroxyprogesterone acetate (Provera) in women following oral and intravaginal administration

Glucocorticoids and medroxyprogesterone acetate synergize with inflammatory stimuli to selectively upregulate CCL20 transcription

The pro-inflammatory cytokine, chemokine (C-C motif) ligand 20 (CCL20), is emerging as a therapeutic target for immune-based therapies. Cooperative regulation of CCL20 by glucocorticoids and progestins used in endocrine therapy and pro-inflammatory mediators could modulate immune function and affect disease outcomes. We show that glucocorticoids as well as medroxyprogesterone acetate (MPA), the progestin widely used in injectable contraception in sub-Saharan Africa, cooperate with pro-inflammatory mediators to upregulate CCL20 protein and/or mRNA in human peripheral blood mononuclear cells (PBMCs) and human cervical cell lines. Changes in CCL20 mRNA levels were shown to be synergistic, as assessed by Chou analysis, cell- and gene-specific and to involve transcriptional regulation, with a requirement for a nuclear factor kappa B (NF-κB) site and glucocorticoid receptor (GR) involvement. The novel results suggest a mechanism whereby MPA, like glucocorticoids, may impact inflammation both systemically and in the genital tract in patients using MPA and/or glucocorticoid therapy.

Variability and quantification of serum medroxyprogesterone acetate levels

Quantification of serum progestin levels in clinical contraceptive studies is now routinely performed to understand progestin pharmacokinetics and to correct for unreliable self-reporting of contraceptive use by study participants. Many such studies are focussed on the three-monthly progestin-only intramuscular (IM) injectable contraceptive depot medroxyprogesterone acetate (DMPA-IM). Methods commonly used to measure serum MPA levels include liquid chromatography coupled to mass spectrometry (LC/MS) and radioimmunoassay (RIA); however, RIA methods have not been used in recent years. We review the available literature and find that these methods vary widely in terms of use of organic solvent extraction, use of derivitization and choice of organic solvent and chromatography columns. There is a lack of standardization of LC/MS methodology, including a lack of detailed extraction protocols. Limited evidence suggests that RIA, without organic solvent extraction, likely over-estimates progestin levels. Maximum MPA concentrations in the first two weeks post-injection show wide inter-individual and inter-study variation, regardless of quantification method used. Standardization of quantification methods and sampling time post-injection is required to improve interpretation of clinical data, in particular the side effects arising at different times depending on the pharmacokinetic profile unique to injectable contraceptives.

Medroxyprogesterone acetate inhibits wound closure of human endometrial epithelial cells and stromal fibroblasts in vitro

Mucosal integrity in the endometrium is essential for immune protection. Since breaches or injury to the epithelial barrier exposes underlying tissue and is hypothesized to increase infection risk, we determined whether endogenous progesterone or three exogenous progestins (medroxyprogesterone acetate (MPA), norethindrone (NET), and levonorgestrel (LNG)) used by women as contraceptives interfere with wound closure of endometrial epithelial cells and fibroblasts in vitro. Progesterone and LNG had no inhibitory effect on wound closure by either epithelial cells or fibroblasts. MPA significantly impaired wound closure in both cell types and delayed the reestablishment of transepithelial resistance by epithelial cells. In contrast to MPA, NET selectively decreased wound closure by stromal fibroblasts but not epithelial cells. Following epithelial injury, MPA but not LNG or NET, blocked the injury-induced upregulation of HBD2, a broad-spectrum antimicrobial implicated in wound healing, but had no effect on the secretion of RANTES, CCL20 and SDF-1α. This study demonstrates that, unlike progesterone and LNG, MPA and NET may interfere with wound closure following injury in the endometrium, potentially conferring a higher risk of pathogen transmission. Our findings highlight the importance of evaluating progestins for their impact on wound repair at mucosal surfaces.

Pharmacokinetics, metabolism and serum concentrations of progestins used in contraception

Many different forms of hormonal contraception are used by millions of women worldwide. These contraceptives differ in the dose and type of synthetic progestogenic compound (progestin) used, as well as the route of administration and whether or not they contain estrogenic compounds. There is an increasing awareness that different forms of contraception and different progestins have different side-effect profiles, in particular their cardiovascular effects, effects on reproductive cancers and susceptibility to infectious diseases. There is a need to develop new methods to suit different needs and with minimal risks, especially in under-resourced areas. This requires a better understanding of the pharmacokinetics, metabolism, serum and tissue concentrations of progestins used in contraception as well as the biological activities of progestins and their metabolites via steroid receptors. Here we review the current knowledge on these topics and identify the research gaps. We show that there is a paucity of research on most of these topics for most progestins. We find that major impediments to clear conclusions on these topics include a lack of standardized methodologies, comparisons between non-parallel clinical studies and variability of data on serum concentrations between and within studies. The latter is most likely due, at least in part, to differences in intrinsic characteristics of participants. The review highlights the importance of insight on these topics in order to provide the best contraceptive options to women with minimal risks.

The Injectable Contraceptive Medroxyprogesterone Acetate Attenuates Mycobacterium tuberculosis-Specific Host Immunity Through the Glucocorticoid Receptor

Background

The effects of the widely used progestin-only injectable contraceptives, medroxyprogesterone acetate (MPA) and norethisterone acetate (NET-A), on host susceptibility to Mycobacterium tuberculosis (Mtb) are unknown.

Methods

We recruited human immunodeficiency virus–uninfected females, not taking any contraceptives, from Cape Town, South Africa, to evaluate the effect of MPA, NET-A, and dexamethasone on Mtb containment in monocyte-derived macrophages co-incubated with purified protein derivative (PPD)–driven peripheral blood–derived effector cells.

Results

MPA (P < .005) and dexamethasone (P < .01), but not NET-A, significantly attenuated Mtb containment in Mtb-infected macrophages co-cultured with PPD-driven effector cells at physiologically relevant concentrations and in a dose-dependent manner. Antagonizing the glucocorticoid receptor with mifepristone (RU486) abrogated the reduction in Mtb containment. In PPD-stimulated peripheral blood mononuclear cells, MPA and dexamethasone, but not NET-A, upregulated (median [interquartile range]) regulatory T cells (5.3% [3.1%–18.2%]; P < .05), reduced CD4⁺ T-cell interferon-γ (21% [0.5%–28%]; P < .05) and granzyme B production (12.6% [7%–13.5%]; P < .05), and reduced CD8⁺ perforin activity (2.2% [0.1%–7%]; P < .05). RU486 reversed regulatory T-cell up-regulation and the inhibitory effect on Th1 and granzyme/perforin-related pathways.

Conclusions

MPA, but not NET-A, subverts mycobacterial containment in vitro and downregulates pathways associated with protective CD8⁺- and CD4⁺-related host immunity via the glucocorticoid receptor. These data potentially inform the selection and use of injectable contraceptives in tuberculosis-endemic countries.

Homologous ELISA for measurement of medroxyprogesterone acetate in serum

In order to develop ELISA for medroxyprogesterone acetate, medroxyprogesterone acetate-3-carboxymethyloxime (MPA-3-CMO) was coupled to bovine serum albumin (BSA) for immunogen preparation and to horseradish peroxidase (HRP) for enzyme conjugate preparation by N-hydroxysuccinimide mediated carbodiimide reaction. The immunogen was used to raise the antiserum in New Zealand white rabbit. The immunoreactivity of MPA-3-CMO-BSA-antibody and MPA-3-CMO-HRP enzyme conjugate was checked by checkerboard assay. The MPA-3-CMO-HRP enzyme conjugate and MPA-3-CMO-BSA-antibody were used for further development, standardization and validation of the assay. Sensitivity, ED₅₀ and affinity of the assay were found to be 0.114 ng/mL, 2.75 ng/mL and 9.9 × 10⁻⁸ L/mol respectively. The % cross-reaction of analogous steroids with MPA-3-CMO-BSA-antibody was less than 0.025%. The recovery of the exogenously spiked MPA serum pools were in the range of 96.83-105.47%. The intra- and inter-assay coefficients of variation was less than 7.02%. The correlation coefficient of the serum level of MPA measured by the developed assay with the commercially available kit was found to be 0.95 (n = 37). This developed ELISA was further validated by measuring serum level of MPA in rat after administering them different doses of MPA intramuscularly.

Progestogens in menopausal hormone therapy

Progestogens share one common effect: the ability to convert proliferative endometrium to its secretory form. In contrast, their biological activity is varied, depending on the chemical structure, pharmacokinetics, receptor affinity and different potency of action. Progestogens are widely used in the treatment of menstrual cycle disturbances, various gynaecological conditions, contraception and menopausal hormone therapy. The administration of progestogen in menopausal hormone therapy is essential in women with an intact uterus to protect against endometrial hyperplasia and cancer. Progestogen selection should be based on the characteristics available for each progestogen type, relying on the assessment of relative potency of action in experimental models and animal models, and on the indirect knowledge brought by studies of the clinical use of different progestogen formulations. The choice of progestogen should involve the conscious use of knowledge of its benefits, with a focus on minimizing potential side effects. Unfortunately, there are no direct clinical studies comparing the metabolic effects of different progestogens.

CCR5 Expression Levels in HIV-Uninfected Women Receiving Hormonal Contraception

Human immunodeficiency virus (HIV) infectivity increases as receptor/coreceptor expression levels increase. We determined peripheral CD4, CCR5, and CXCR4 expression levels in HIV-uninfected women who used depot medroxyprogesterone acetate (DMPA; n = 32), the levonorgestrel-releasing intrauterine device (LNG-IUD; n = 27), oral contraceptive pills (n = 32), or no hormonal contraception (n = 33). The use of LNG-IUD increased the proportion of CD4(+) and CD8(+) T cells that expressed CCR5; increases in the magnitude of T-cell subset CCR5 expression were observed with DMPA and LNG-IUD use (P < .01 for all comparisons). LNG-IUD and, to a lesser extent, DMPA use were associated with increased peripheral T-cell CCR5 expression.

The progestin-only contraceptive medroxyprogesterone acetate, but not norethisterone acetate, enhances HIV-1 Vpr-mediated apoptosis in human CD4+ T cells through the glucocorticoid receptor

The glucocorticoid receptor (GR) regulates several physiological functions, including immune function and apoptosis. The HIV-1 virus accessory protein, viral protein R (Vpr), can modulate the transcriptional response of the GR. Glucocorticoids (GCs) and Vpr have been reported to induce apoptosis in various cells, including T-cells. We have previously shown that the injectable contraceptive, medroxyprogesterone acetate (MPA) is a partial to full agonist for the GR, unlike norethisterone acetate (NET-A). We investigated the functional cross talk between the GR and Vpr in inducing apoptosis in CD4(+) T-cells, in the absence and presence of GCs and these progestins, as well as progesterone. By using flow cytometry, we show that, in contrast to NET-A and progesterone, the synthetic GR ligand dexamethasone (Dex), cortisol and MPA induce apoptosis in primary CD4(+) T-cells. Furthermore, the C-terminal part of the Vpr peptide, or HIV-1 pseudovirus, together with Dex or MPA further increased the apoptotic phenotype, unlike NET-A and progesterone. By a combination of Western blotting, PCR and the use of receptor- selective agonists, we provide evidence that the GR and the estrogen receptor are the only steroid receptors expressed in peripheral blood mononuclear cells. These results, together with the findings that RU486, a GR antagonist, prevents Dex-, MPA- and Vpr-mediated apoptosis, provide evidence for the first time that GR agonists or partial agonists increase apoptosis in primary CD4(+) T-cells via the GR. We show that apoptotic induction involves differential expression of key apoptotic genes by both Vpr and GCs/MPA. This work suggests that contraceptive doses of MPA but not NET-A or physiological doses of progesterone could potentially accelerate depletion of CD4(+) T-cells in a GR-dependent fashion in HIV-1 positive women, thereby contributing to immunodeficiency. The results imply that choice of progestin used in contraception may be critical to susceptibility and progression of diseases such as HIV-1.

Progestogen levels, progesterone receptor gene polymorphisms, and mammographic density changes: results from the Postmenopausal Estrogen/Progestin Interventions Mammographic Density Study

OBJECTIVE

Estrogen plus progestin therapy (EPT) in postmenopausal women increases breast cancer risk and mammographic density to a higher extent than does estrogen therapy alone. Data from the randomized placebo-controlled Postmenopausal Estrogen/Progestinv Interventions trial showed that EPT-induced increases in serum estrone and estrone sulfate levels were positively correlated with increases in mammographic density. Here, after adjusting for serum estrone and estrone sulfate levels, we investigated the roles of posttreatment serum progestogen increase and of progesterone receptor gene (PGR) genetic variations on changes in mammographic density.

METHODS

We measured the percent mammographic density and serum progestogen levels in 280 Postmenopausal Estrogen/Progestin Interventions trial participants randomized to EPT treatment. Analyses of genetic variations in PGR were limited to 260 white women for whom we successfully obtained PGR genotypes. We used linear regression analyses to determine how an increase in progestogen levels and PGR genetic variation influenced mammographic density change after EPT.

RESULTS

The increase in posttreatment serum progestogen level was positively associated with greater increases in mammographic density after adjustment for covariates (P trend = 0.044). Compared with women in the lowest quartile of serum progestogen level, women in the highest quartile experienced a 3.5% greater increase in mammographic density (P = 0.046). We did not find a strong indication that genetic variation in PGR was associated with mammographic density increase or modified the association with serum progestogen; however, confidence in these null findings is constrained by our small sample size.

CONCLUSIONS

Our results suggest that higher serum progestogen levels resulting from EPT treatment lead to greater increases in mammographic density.

Molecular mechanisms of steroid receptor-mediated actions by synthetic progestins used in HRT and contraception

Synthetic progestins are used by millions of women as contraceptives and in hormone replacement therapy (HRT), although their molecular mechanisms of action are not well understood. The importance of investigating these mechanisms, as compared to those of progesterone, has been highlighted by clinical evidence showing that medroxyprogesterone acetate (MPA), a first generation progestin, increases the risk of breast cancer and coronary heart disease in HRT users. A diverse range of later generation progestins with varying structures and pharmacological properties is available for therapeutic use and it is becoming clear that different progestins elicit beneficial and adverse effects to different extents. These differences in biological activity are likely to be due to many factors including variations in dose, metabolism, pharmacokinetics, bioavailability, and regulation of, and/or binding, to serum-binding proteins and steroidogenic enzymes. Since the intracellular effects on gene expression and cell signaling of steroids are mediated via intracellular steroid receptors, differential actions via the progesterone and other steroid receptors and their isoforms, are likely to be the major cause of differential intracellular actions of progestins. Since many progestins bind not only to the progesterone receptor, but also to the glucocorticoid, androgen, mineralocorticoid, and possibly the estrogen receptors, it is plausible that synthetic progestins exert therapeutic actions as well as side-effects via some of these receptors. Here we review the molecular mechanisms of intracellular actions of old (MPA, norethisterone, levonorgestrel, gestodene) vs. new (drospirenone, dienogest, trimegestone) generation progestins, via steroid receptors.

Effects of progesterone, levonorgestrel and medroxyprogesterone acetate on apoptosis in human endometrial endothelial cells

BACKGROUND

We evaluated apoptosis in human endometrial endothelial cells (HEECs) incubated with progesterone, levonorgestrel (LNG) and medroxyprogesterone acetate (MPA).

STUDY DESIGN

HEECs were cultured to near confluence, and the progestogens were added.

SETTING

Academic Department of Obstetrics and Gynecology.

PATIENTS

No patients were involved.

INTERVENTIONS

Progestogens at 5-, 250- and 500-ng/mL concentrations were added to incubations of HEECs for 12, 24 and 48 h.

MAIN OUTCOME MEASURE

Apoptosis based on terminal deoxynucleotidyl transferase-mediated deoxy-UTP nick-end labeling (TUNEL), and semiquantification of Bax and Bcl-2.

RESULTS

No apoptosis was found by TUNEL, Bax and Bcl-2 after 12 h incubation with any progestogen. TUNEL increased after incubation for 24 and 48 h with progesterone 500 ng/mL; LNG 250, 500 ng/mL and all concentrations of MPA (p<.001), Bax increased and Bcl-2 decreased at all concentrations of MPA and the two highest concentrations of LNG at 48 h (p<.05).

CONCLUSION

MPA results in apoptosis of HEECs.

Effect of depot medroxyprogesterone acetate on glucose tolerance in generalized lipodystrophy

BACKGROUND

Lipodystrophy is a rare condition causing severe insulin resistance and frank diabetes. Depot medroxyprogesterone acetate (DMPA), a commonly used contraceptive, may worsen glucose tolerance in diabetics and those with lipodystrophy.

CASE

A young woman with generalized lipodystrophy, who previously required greater than 1,000 units of insulin daily, had a normal hemoglobin A1c on leptin and metformin only. After an injection of DMPA, she developed severe hyperglycemia. Her levels returned to near normal only with extremely high doses of insulin (up to 1,700 units/d) and increased doses of leptin and metformin.

CONCLUSION

Progestin-only contraceptives may detrimentally affect glucose tolerance, particularly in patients with lipodystrophy, a cause of severe insulin resistance and leptin deficiency. One DMPA injection appeared to profoundly alter glucose metabolism in this patient with frank diabetes resulting from lipodystrophy. The effect of progestin-only contraceptives on glucose tolerance should be monitored closely in any diabetic patient.

Progestins inhibit the neuroprotective effects of estrogen in rat hippocampus

Although estrogen has beneficial actions in brain, recent clinical trials demonstrated adverse neural effects of hormone therapy in postmenopausal women. The cause(s) of this disconnect between experimental and clinical findings may include unanticipated effects of progestins. We report that both natural progesterone and the clinical progestin medroxyprogesterone acetate block estrogen neuroprotection. These findings underscore the need to evaluate neural actions of progestins in the rational design of hormone therapy.

Medroxyprogesterone acetate and dihydrotestosterone induce coronary hyperreactivity in intact male rhesus monkeys

Coronary hyperreactivity (CH), characterized by persistent severe vasoconstrictions in response to vasoconstrictor challenge, is oppositely influenced by progesterone (P) and medroxyprogesterone acetate (MPA) treatment in surgically menopausal primates. In this study we tested whether multiweek MPA or dihydrotestosterone (DHT) exposure induced CH in intact male rhesus monkeys. Coronary angiographic experiments with intracoronary serotonin and the thromboxane A(2) analog U46619 stimulated brief vasoconstriction (for 1-3 min) in large epicardial coronaries in untreated male monkeys. In contrast, MPA- and DHT-treated monkeys displayed long-duration constrictions (>5 min), with significantly greater reductions in the minimal diameters of epicardial coronaries. Immunocytochemistry demonstrated androgen receptors (AR) and P receptors in aorta and coronary arteries, and immunocytochemistry and Western blotting showed AR and P receptors in rhesus coronary vascular muscle cells. In vivo, MPA or DHT increased thromboxane prostanoid (TP) receptor expression in the aorta. In vitro, MPA or DHT increased, whereas P did not change, TP receptor expression in primary coronary vascular muscle cell. This MPA- or DHT-mediated increase in TP receptor expression was attenuated by the AR antagonist flutamide. MPA or DHT induction of CH in intact adult male primates, hypothesized to occur via androgenic up-regulation of vascular muscle TP receptor expression, could predispose to CH-mediated myocardial ischemia.

Differential signal transduction of progesterone and medroxyprogesterone acetate in human endothelial cells

The conjugated equine estrogens-only arm of the Women's Health Initiative trial, showing a trend toward protection from heart disease as opposed to women receiving also medroxyprogesterone acetate (MPA), strengthens the debate on the cardiovascular effects of progestins. We compared the effects of progesterone (P) or MPA on the synthesis of nitric oxide and on the expression of leukocyte adhesion molecules, characterizing the signaling events recruited by these compounds. Although P significantly increases nitric oxide synthesis via transcriptional and nontranscriptional mechanisms, MPA is devoid of such effects. Moreover, when used together with physiological estradiol (E2) concentrations, P potentiates E2 effects, whereas MPA impairs E2 signaling. These findings are observed both in isolated human endothelial cells as well as in vivo, in ovariectomized rat aortas. A marked difference in the recruitment of MAPK and phosphatidylinositol-3 kinase explains the divergent effects of the two gestagens. In addition, both P and MPA decrease the adhesiveness of endothelial cells for leukocytes when given alone or with estrogen. MPA is more potent than P in inhibiting the expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1. However, when administered together with physiological amounts of glucocorticoids, MPA (which also binds glucocorticoid receptor) markedly interferes with the hydrocortisone-dependent stabilization of the transcription factor nuclear factor kappaB and with the expression of adhesion molecules, acting as a partial glucocorticoid receptor antagonist. Our findings show significant differences in the signal transduction pathways recruited by P and MPA in endothelial cells, which may have relevant clinical implications.

All progestins are not created equal

A variety of progestins are available for therapeutic use. It is convenient to classify them into those related in chemical structure to progesterone or testosterone. Progestins related to progesterone can be subdivided into pregnanes and 19-norpregnanes, whereas those related to testosterone can be subdivided into those with and without a 17-ethinyl group. 17-Ethinylated progestins consist of the families of norethindrone (estranes) and levonorgestrel (13-ethylgonanes). Progestins administered orally undergo extensive hepatic first pass metabolism primarily by reduction and conjugation, and in most instances, relatively high progestin doses are required for therapeutic use. There are limited reliable data on the pharmacokinetics of most progestins. Some progestins are prodrugs, requiring transformation prior to exhibiting progestational activity. Qualitative and quantitative tests utilizing either human or animal species have been used to establish progestin potency. However, profound differences in progestational activity are often observed between human and animal tissues. Also, there is a misconception about androgenicity of progestins due largely to extrapolation of data from rat studies to the human. Progestins differ widely in their chemical structures, structure-function relationships, metabolism, pharmacokinetics, and potencies; they are not created equal.

Estrogen increases endothelial nitric oxide synthase via estrogen receptors in rat cerebral blood vessels: effect preserved after concurrent treatment with medroxyprogesterone acetate or progesterone

BACKGROUND AND PURPOSE

In vivo and in vitro rat models of hormone therapy were used to test the following hypotheses: (1) estrogen acts directly on cerebrovascular estrogen receptors to increase endothelial nitric oxide synthase (eNOS); (2) increased protein correlates with higher NOS activity; and (3) effects of estrogen on eNOS are altered by concurrent treatment with either medroxyprogesterone acetate (MPA) or progesterone.

METHODS

Blood vessels were isolated from brains of ovariectomized female rats; some were treated for 1 month with estrogen, estrogen and progesterone, or estrogen and MPA. Isolated cerebral vessels were also treated in vitro with estrogen in the absence and presence of progesterone, MPA, tamoxifen, and the estrogen receptor antagonist ICI 182 780. Levels of eNOS were measured by Western blot, and NOS activity was measured by [14C]arginine-[14C]citrulline conversion.

RESULTS

Chronic hormone treatment in vivo resulted in plasma levels of 17beta-estradiol, progesterone, and MPA in the range of values found in humans. Estrogen treatment resulted in higher levels of cerebrovascular NOS activity that paralleled increases in eNOS protein. In vitro estrogen treatment for 18 hours also resulted in a concentration-dependent increase in eNOS protein (EC50 approximately 300 pmol/L) that was completely prevented by estrogen receptor antagonists tamoxifen or ICI 182 780. However, cotreatment with progesterone or MPA, either in vivo or in vitro, did not alter the effect of estrogen on eNOS protein.

CONCLUSIONS

Estrogen receptor activation in cerebrovascular tissue results in increased eNOS activity and protein levels. The latter effect persists in the presence of either progesterone or MPA. Thus, increased NO production by eNOS may contribute to the neuroprotective effects of estrogen.

Ovarian steroid protection against coronary artery hyperreactivity in rhesus monkeys

Our hypothesis was that estrogen and progesterone modulate coronary artery reactivity in rhesus monkeys. Adult ovariectomized (ovx) monkeys were treated for 1, 2, or 4 wk with physiological concentrations of 17 beta-estradiol (E2), natural progesterone (P), and/or therapeutic levels of medroxyprogesterone acetate (MPA). Steroid concentrations in venous blood, coronary artery estrogen receptor (ER) and progesterone receptor (PR) localization, and isolated vascular muscle cell (VMC) Ca2+ and protein kinase C responses to serotonin and U46619 (a thromboxane A2 mimetic) were measured. Ovx monkey VMC responses were hyperreactive, showing prolonged increases in intracellular Ca2+ and protein kinase C that correlated with exaggerated in vivo coronary artery vasoconstrictor responses. The hyperreactive Ca2+ responses were abolished by in vivo treatment with E2 and/or P. However, VMC from ovx monkeys treated with the combination of E2 and MPA or E2, P, and MPA remained hyperreactive to vasoconstrictor stimuli, suggesting that MPA negated the protective effects of E2. ER were detected primarily in interstitial and endothelial cells and a minor fraction of the VMC. PR were localized to coronary artery VMC and interstitial cell nuclei. In vivo treatment of ovx monkeys with E2 tended to up-regulate PR in VMC, but MPA appeared to down-regulate PR expression. These results suggest that E2 and P replacement decreases coronary artery reactivity through direct interactions with ER and PR in coronary artery VMC.

Medroxyprogesterone interferes with ovarian steroid protection against coronary vasospasm

Cardiovascular disease, the major cause of death in post-menopausal women, can be reduced by replacement of ovarian steroid hormones. To compare medroxyprogesterone with progesterone as the progestin in hormone replacement therapy from the standpoint of coronary artery vasospasm, we treated ovariectomized rhesus monkeys with physiological levels of estradiol-17 beta in combination with medroxyprogesterone or progesterone for four weeks. Coronary vasospasm in response to pathophysiological stimulation without injury showed that progesterone plus estradiol protected but medroxyprogesterone plus estradiol failed to protect, allowing vasospasm. We conclude that medroxyprogesterone in contrast to progesterone increases the risk of coronary vasospasm.

Enzyme immunoassay for nomegestrol acetate in human plasma

Currently available chromatographic assays of the progestative drug nomegestrol acetate in human plasma are not suitable for monitoring drug kinetics more than 24 h after clinical dosage. A specific and sensitive enzyme immunoassay was therefore developed. A 3(O-carboxymethyl)oxime derivative of nomegestrol acetate was synthesized and coupled to bovine serum albumin in order to raise polyclonal antibodies in rabbits. The enzymatic tracer was obtained by coupling the 3(O-carboxymethyl)oxime derivative to acetylcholinesterase (E.C.3.1.1.7.). HPLC fractionation of human plasma samples followed by enzyme immunoassay revealed the presence of cross-reacting metabolites. An automated procedure of metabolite separation was developed using silica bonded with diol groups (Diol Bakerbond column). This procedure ensured assay specificity. The quantification limit in human plasma was 0.1 ng/ml. Mean repeatability (intra-assay variation) and reproducibility (inter-assay variation) were 9 and 15%, respectively. The enzyme immunoassay allowed monitoring of the kinetics of nomegestrol acetate 144 h after oral administration of a single 5 mg dose. Values for human samples were in excellent agreement with those assayable by HPLC followed by u.v. detection.

An enzyme linked immunosorbent assay (ELISA) for plasma medroxyprogesterone acetate (MPA)

A single extraction fixed antigen enzyme-linked immunosorbent assay (ELISA) that can be completed in less than 24 h is described for the measurement of medroxyprogesterone acetate (MPA) in plasma. MPA is covalently coupled to bovine thyroglobulin and passively adsorbed in guanidine hydrochloride to a standard 96-well microtitre plate where it competes with MPA in the extracted plasma sample for goat anti-MPA. Antibody binding to the solid phase is determined via binding of a horse-radish peroxidase second antibody which reacts colorimetrically with its substrate. The reaction is stopped by addition of 1.25 M H2SO4 and absorbance read at 492 nm. All steps except for sample addition and extraction can be performed on an automatic ELISA processing machine. The assay is sensitive, specific and precise, with intra- and inter-assay coefficients of variation of less than 10 and 15%, respectively. Assay sensitivity is 0.08 ng/ml. The assay follows established methodology for other assays in this laboratory which assists standardization, cost structure and sample throughput and thus is a useful alternative to radioimmunoassays for the determination of MPA in plasma.

Progestins in breast cancer treatment. A review

The two most widely used synthetic progestins in breast cancer treatment, medroxyprogesterone acetate (MPA) and megestrol acetate (MA), are reviewed with regard to pharmacological, endocrinological and clinical aspects. In high oral doses as second- or first-line endocrine therapy in advanced breast cancer, they give a similar response rate as tamoxifen (TAM) and aminoglutethimide (AG). The mechanism of action is probably complex. Considerable changes in serum levels of different hormones are induced by progestin treatment. The decrease of serum estrone sulfate (E1S) may be part of the therapeutic mechanism. Some studies suggest that the two drugs, MPA and MA, have a different mode of action, and possibly a low cross resistance. Randomized studies using the two progestins with a cross-over design may answer these questions. Further studies on the influence of progestin on different receptors and growth factors are warranted. To determine the most effective clinical dose of the two progestins, studies with increasing therapeutic doses are needed.

Specific and sensitive quantitation of medroxyprogesterone acetate in human serum by gas chromatography-mass spectrometry

A procedure for the quantitation of medroxyprogesterone acetate in serum using gas chromatography-quadrupole mass spectrometry is described. Medroxyprogesterone propionate, synthesized from medroxyprogesterone, was used as the internal standard. The serum samples were extracted on Bond Elut C18 cartridges, and the acetate and propionate were determined as their 3-enol heptafluorobutyrate esters by selected-ion monitoring technique. The linear range of the standard curve in serum was 0.5-30 ng/ml with a lower limit of quantitation of 0.5 ng/ml. The coefficient of variation of the method was 3.1% at 10 ng/ml and 5.5% at 1 ng/ml. The method is very rapid, and it has been applied for routine measurements of medroxyprogesterone acetate levels in human serum after oral administration of 10 or 20 mg.

Embryotoxicity of a single dose of medroxyprogesterone acetate (MPA) and maternal serum MPA concentrations in cynomolgus monkey (Macaca fascicularis)

A single dose of MPA (Depo-Provera; Upjohn Co., Kalamazoo, Michigan) was administered intramuscularly to 12 time-mated pregnant cynomolgus monkeys on day 27 (+/- 2) of gestation at 25 mg/kg or at 100 mg/kg. Maternal blood samples were collected immediately prior to MPA injection and then at regular intervals until cesarean section at term (day 152 +/- 3). Infants in both dose groups had external genital abnormalities. Female infants in the low-dose groups had partial or complete labial fusion, prominent median raphe, and clitoral hypertrophy; at high doses (100 mg/kg), the female infants had complete labial fusion and a distinct penile urethra. MPA had an opposite effect on external genitalia of male infants. The penis was short and the scrotal swelling was absent or less conspicuous, and two males had hypospadias. The adrenal glands were significantly smaller (P less than 0.05) in infants of both sexes treated with 100 mg/kg. One of the infants treated with 25 mg/kg of MPA had a muscular ventricular septal defect. Serum concentrations of MPA were determined by radioimmunoassay in eight pregnant monkeys. In the 25 mg/kg group the patterns of MPA profiles in the serum were similar in all four animals. An initial peak occurred at 24-48 hr postinjection (2.7-9.6 ng/ml), followed by a slight decrease at 3 days postinjection (gestational day 30), and then a steady increase to maximum levels of 10-14 ng/ml occurring between gestational days 37 and 50. Serum levels gradually declined to concentrations below 5 ng/ml by midgestation in three of four monkeys. By comparison, both the patterns and magnitude of MPA concentration showed great interanimal variation in the 100 mg/kg group. MPA was present in cord blood at measurable concentrations in infants at both dose groups; the levels ranged from 0.6 to 8.3 ng/ml, corresponding to 40-72% of the maternal concentrations. These results demonstrate that a single injection of MPA during early pregnancy causes selective embryotoxicity in both male and female fetuses. Presence of high levels of MPA in maternal sera during the critical period of genital development can cause specific genital defects; however, the exact mechanism by which MPA causes these paradoxical genital abnormalities is unknown.

Specific and sensitive determination of medroxyprogesterone acetate in human serum by gas chromatography-mass spectrometry

The mass fragmentographic determination of medroxyprogesterone acetate (MPA) in serum, using as internal standard medroxyprogesterone propionate (MPP) synthesized from MPA, is described. After addition of MPP, the sera are extracted on Sep-Pak C18 cartridges and MPA and MPP are detected as their respective 3-enol trifluoroacyl esters. Serum samples from 84 patients with breast cancer, daily receiving MPA orally, were determined showing a large variation in MPA concentrations (4-349 ng/ml). Our proposed gas chromatographic-mass spectrometric (GC-MS) method, which can be considered as a reference, was compared with a radioimmunoassay (RIA) method showing a correlation coefficient of 0.73 (n = 69; p much less than 0.001). The assay was also used to determine sequential serum levels of patients receiving a single oral dose of MPA. With only minor adjustments, the GC-MS method allows the determination of serum concentrations of related steroids such as megestrol acetate and cyproterone acetate.

Embryotoxicity and maternal serum concentrations of medroxyprogesterone acetate (MPA) in baboons (Papio cynocephalus)

A single dose of MPA (Depo-Provera; Upjohn Co.; USA) was administered intramuscularly on day 27 (+/- 2) of gestation to three dosage groups of pregnant baboons. The dosage expressed as mg/kg corresponded to 1 (2.5 mg/kg), 10 (25 mg/kg) and 40 (100 mg/kg) times the human contraceptive dose equivalent (HDE) based on body weight. Injectable MPA was not teratogenic in baboons at 1x HDE. The teratogenicity was confined to the higher doses which included malformations of the external genitalia at 10x and 40x HDE and adrenal gland hypoplasia at 40x HDE. The maternal serum MPA concentrations were high during the critical period of adrenal and genital development. The pattern of MPA concentrations in maternal sera was similar between animals in the low dose group (10x HDE). In contrast, animals in the high dose group (40x HDE) showed interanimal variations in maternal serum concentrations of MPA. This study has demonstrated that injectable MPA is not teratogenic in baboons at human contraceptive dose equivalent and, even at higher doses, does not result in any nontarget organ malformations.

Long acting contraceptives. Present status

Long acting injectable hormonal contraceptives are among the most effective fertility regulating agents developed; yet they are also among the most controversial because of animal data indicating a possible carcinogenic potential in several species. A critical analysis of these animal findings has revealed, in all instances, the existence of specific mechanisms not occurring in the human. For this reason, most national and international scientific bodies who have reviewed this issue have concluded that there are no toxicological reasons for not using long acting hormonal contraceptives. Long acting agents can be divided into 2 separate groups: those having a duration of action of one month, which are composed of a long acting oestrogen and a progestagen, and those lasting for several months which consist of only a progestagen. Among the injectable progestagen-only contraceptives tested, only 2 have so far reached the international market: depot medroxyprogesterone acetate (DMPA), which has been administered at 3- or 6-month intervals and norethisterone enanthate, which has been injected at intervals ranging between 2 and 3 months. The most important side effect observed with these 2 agents is a complete disruption of the menstrual bleeding pattern, leading - in some cases - to total amenorrhoea, which is more frequent with depot medroxyprogesterone acetate than with norethisterone enanthate. The latter, however, has a shorter duration of action with a higher pregnancy rate than the former. Other adverse reactions are rare and of no real importance. Metabolic effects with progestagen-only injectable preparations are, in general, mild and less marked than with combined oestrogen-progestagen formulations. Recent investigations have shown that the return of fertility following their use is delayed but in no way impaired. Monthly injectable oestrogen-progestagen combinations have been tested to a more limited extent and these agents are available only in a very few countries. Their main advantage over progestagen-only preparations is that they allow a reasonable menstrual bleeding pattern in the majority of cases. Their obvious disadvantage is that they contain a long acting oestrogen.

Plasma concentrations of megestrol acetate and medroxyprogesterone acetate after single oral administration to healthy subjects

Plasma concentrations of megestrol acetate (MA) were measured by radioimmunoassay (RIA) after a single oral dose of 60 mg either in the form of one tablet, or four 15 mg tablets, to 10 women 21-40 years old using a cross-over design. No statistically significant difference between the two preparations was observed with respect to plasma concentrations, the area under the curve from 0 to 24 h or the maximum concentration (c(max)). For comparison, data are presented on the plasma level of medroxyprogesterone acetate (MPA) following a single oral dose of 100 mg given using a cross-over design in two different tablet forms to 10 healthy men, when no significant difference was observed for these parameters. The mean c(max) for MA after 2.6 h was 43.9 ng/ml (range 21.7-87.7 ng/ml), whereas that for MPA at 3.1 h was 13.1 ng/ml (range 4.4-29.5 ng/ml) despite the higher dose. After 24 h immunoreactive MA and MPA ranged from 9.6 to 29.0 ng/ml and from 0.2 to 4.0 ng/ml respectively. Moreover, it was found that petroleum ether extraction gives the most specific result by RIA, although considerable amounts of metabolites are still co-estimated. By comparison with selected ion monitoring using GC-MS, metabolite interference in RIA increases with time after administration of the steroids and is considerably greater for MPA than for MA. It is concluded that after oral administration the relative bioavailability of MA is significantly better than that of MPA.

The Depo-Provera debate. Commentary on the article "Depo-Provera, a critical analysis"

A widely publicized article has in recent months caused a great deal of concern among individuals interested in responsible promotion of family planning. The article contains a long series of factual errors, distortions and biased quotations. This commentary presents evidence, based on current knowledge, that Depo-Provera is a satisfactory contraceptive with several advantages and some disadvantages, and poses no more unresolved problems than oral contraceptives. There is no evidence that, at contraceptive doses, it increases the risk of cancer, impairs bone mineralization, "shocks" the hypothalamus, damages the liver or the immune system, or causes premature aging. Studies to date have not shown damaging effects on infants exposed to the drug in utero or via breast milk. To most women, disruption of the menstrual cycle, the major side effect, is not a health hazard. Finally, women in various parts of the world have shown to be quite capable of choosing for themselves whether or not the advantages of the drug can overcome the disadvantage of almost certain menstrual disturbance.

Specific quantitation of plasma medroxyprogesterone acetate by gas chromatography/mass spectrometry

Investigation of various derivatives (O-methyloxime, trifluoroenol acetate and t-butyldimethylsilyl enol ether) coupled with the efficient preparation of a trideuterated analogue of medroxyprogesterone acetate, has allowed the development of a rapid and accurate assay for its quantitation in plasma by isotope dilution gas chromatography/mass spectrometry. High oral doses (2.8 g weekly) of medroxyprogesterone acetate are shown to lead consistently to plasma levels of less than 16 ng.ml-1.