Metabolism of levonorgestrel, norethindrone, and structurally related contraceptive steroids

Drug-Drug Interaction Potential of Mavacamten with Oral Contraceptives: Results from a Clinical Pharmacokinetic Study and a Physiologically Based Pharmacokinetic Model

Mavacamten is a potential inducer of cytochrome P450 (CYP) 3A4 and, as such, could reduce the exposure of the active components of oral contraceptives, ethinyl estradiol (EE) and norethindrone (NOR), where CYP3A4 is involved in metabolism. This study assessed if repeat doses of mavacamten led to a drug-drug interaction with EE and/or NOR. This was an open-label study in healthy women. In Period 1, participants received 35 mcg of EE and 1 mg of NOR. In Period 2, participants received oral loading doses of mavacamten 25 mg on Days 1-2, 15 mg/day on Days 3-17, and 35 mcg of EE and 1 mg of NOR on Day 15. Plasma concentrations of mavacamten, EE, and NOR were obtained before dosing and up to 72 hours after dosing. For EE only, a physiologically based pharmacokinetic model was used to simulate mavacamten-mediated CYP3A4 induction with EE for various CYP2C19 phenotypes. In total, 13 women were enrolled (mean age, 38.9 [standard deviation, 9.65] years). After mavacamten administration, modest increases in area under the concentration-time curves were observed for both EE and NOR. The maximum concentrations and half-lives for EE and NOR were not affected by coadministration with mavacamten. Criteria for bioequivalence were met or nearly met for EE and NOR exposure with geometric mean ratios between 0.8 and 1.25. All adverse events were mild. The physiologically based pharmacokinetic model predicted a less than 15% decrease in EE exposure across CYP2C19 phenotypes. Coadministration of mavacamten at a therapeutically relevant dose with EE and NOR did not decrease the exposure to either EE or NOR to a level that may lead to reduced effectiveness.

Progesterone receptor isoform ratios influence the transcriptional activity of progestins via the progesterone receptor

Progestins (synthetic progestogens) are progesterone receptor (PR) ligands used globally by women in both hormonal contraception and menopausal hormone therapy. Although four generations of unique progestins have been developed, studies seldom distinguish between the activities of progestins via the two functionally distinct PR isoforms, PR-A and PR-B. Moreover, not much is known about the action of progestins in breast cancer tumors where PR-A is mostly overexpressed relative to PR-B. Understanding progestin action in breast cancer is crucial since the clinical use of some progestins has been associated with an increased risk of developing breast cancer. This study directly compared the agonist activities of selected progestins from all four generations for transactivation and transrepression via either PR-A or PR-B, and when PR-A and PR-B were co-expressed at ratios comparable to those detected in breast cancer tumors. Comparative dose-response analysis showed that earlier generation progestins mostly displayed similar efficacies for transactivation on a minimal progesterone response element via the PR isoforms, while most of the 4th generation progestins, similar to the natural progestogen, progesterone (P4), were more efficacious via PR-B. Most of the progestogens were however more potent via PR-A. We are the first to show that the efficacies of the selected progestogens via the individual PR isoforms were generally decreased when PR-A and PR-B were co-expressed, irrespective of the ratio of PR-A:PR-B. While the potencies of most progestogens via PR-B were enhanced when the ratio of PR-A relative to PR-B was increased, those via PR-A were minimally influenced. This study is also the first to report that all progestogens evaluated, except 1st generation medroxyprogesterone acetate and 4th generation drospirenone, displayed similar agonist activity for transrepression via PR-A and PR-B on a minimal nuclear factor kappa B containing promoter. Moreover, we showed that the progestogen activity for transrepression was significantly increased when PR-A and PR-B were co-expressed. Taken together, our results highlight that PR agonists (progestogens) do not always display the same activity via PR-A and PR-B, or when PR-A and PR-B are co-expressed at ratios mimicking those found in breast cancer tumors. These results suggest that biological responses are progestogen- and PR isoform-dependent and may differ in target tissues expressing varying PR-A:PR-B ratios.

Lack of Effect of Cenerimod, a Selective S1P1 Receptor Modulator, on the Pharmacokinetics of a Combined Oral Contraceptive

Cenerimod, a sphingosine-1-phosphate 1 receptor modulator, is in development for the treatment of systemic lupus erythematosus, a disease mainly affecting women of childbearing potential. The effect of cenerimod on the pharmacokinetics (PK) of a combined oral contraceptive (COC, 100 µg levonorgestrel and 20 µg ethinylestradiol (EE)) was investigated. A randomized, double-blind, parallel-group study was performed in 24 healthy male and female subjects. A single oral dose of COC was administered alone and after 35 days of once daily (o.d.) administration of cenerimod 0.5 (n = 10) or 4 (n = 14) mg. Exposure to EE alone or in combination with cenerimod was comparable as reflected by the geometric mean ratios and the respective 90% confidence intervals, while a slight increase in exposure (approximately 10-25%) to levonorgestrel was observed at clinically relevant concentrations of cenerimod. Overall, COC alone or in combination with cenerimod was safe and well tolerated. Two subjects reported one adverse event each (one headache after COC alone, and gastroenteritis in combination with cenerimod 4 mg). In conclusion, cenerimod does not affect the PK of levonorgestrel or EE to a clinically relevant extent. Therefore, COC can be selected as method of contraception during and after cenerimod therapy without the risk of interaction.

Detecting falsified oral contraceptives by visual assessment and diffuse reflectance spectroscopy (350–2500 nm): the need for supplementing traditional pharmacopeia techniques and the public health implications

Objectives

Substandard and falsified pharmaceuticals can present a major health risk, particularly for low- and middle-income countries. In a Sub-Saharan African market, United States Agency for International Development (USAID) staff found an oral contraceptive product (0.15 mg levonorgestrel/0.03 mg ethinyl estradiol) labeled with a logo (and brand name) visually matching one historically used by USAID but purportedly manufactured by an unauthorized source. Additional assessment was conducted to determine if more evidence of falsification was present to better understand the public health impact.

Study design

Relative to a control, the suspect sample was assessed visually for tablet features and with United States and International Pharmacopeia methods for levonorgestrel/ethinyl estradiol tablets. Diffuse reflectance spectra (350–2500 nm) were collected to further characterize the sample.

Results

Although the suspect sample aligned with pharmacopeia tests, visual examination of tablet characteristics and diffuse reflectance spectroscopy (350–2500 nm) assessments supported the tablets were not the same as control samples, confirming the suspect sample was falsified. These results raised concerns for the overall regulatory oversight available for the market with uncertainty regarding the true clinical bioequivalence levels (although adequate dissolution levels were observed).

Conclusions

Comprehensive characterization of suspect pharmaceuticals from the field can often be required depending on the nature of the sample and can have dramatic implications for understanding the public health risks to the end user within the local market. Simple visual assessment and spectroscopic techniques to screen a sample can help to supplement traditional pharmacopeia approaches.

Implications

Proper characterization of suspect pharmaceuticals is necessary to best understand their potential public health impact. Situations can occur where traditional pharmacopeial techniques may not adequately characterize a sample. Visual assessments and diffuse reflectance spectroscopy can be supplemented to provide a more holistic analysis.

Synthetic Progestins in Waste and Surface Waters: Concentrations, Impacts and Ecological Risk

Synthetic progestins (PGs) are a large family of hormones used in continuously growing amounts in human and animal contraception and medicinal therapies. Because wastewater treatment plants (WWTPs) are unable to eradicate PGs after excretion, they are discharged into aquatic systems, where they can also be regenerated from conjugated PG metabolites. This review summarises the concentrations of 12 PGs in waters from 2015 to 2021. The selected PGs were considered of particular interest due to their wide use, activity, and hormonal derivation (from testosterone, progesterone, and spirolactone). We concluded that PGs had been analysed in WWTPs influents and effluents and, to a lesser extent, in other matrices, including surface waters, where their concentrations range from ng/L to a few µg/L. Because of their high affinity for cell hormone receptors, PGs are endocrine disruptor compounds that may alter the reproductive fitness and development of biota. This review focused on their biological effects in fish, which are the most used aquatic model organisms to qualify the impacts of PGs, highlighting the risks that environmental concentrations pose to their health, fecundity, and fertility. It is concluded that PGs research should be expanded because of the still limited data on their environmental concentrations and effects.

Clinical pharmacology of progestins

INTRODUCTION

In this paper, we report general pharmacological profile and major biological activities of natural progesterone (P) and progestins. The aim of this article consists of synthesizing the principal aspects of pharmacology and metabolism of P and progestins related to the clinical consequences of their use.

METHODS

We review scientific literature on the topic "Progestins", evaluating the most relevant data from original articles, reviews and meta-analyses.

EVIDENCE SYNTHESIS

Progestins represent a specific class of synthetic analogues of P clinically employed (alone or associated with estrogens) to manage several gynaecological conditions, for instance multiple abortions, luteal phase defect, premenstrual syndrome, abnormal uterine bleeding, endometriosis and menopause (for hormone replacement therapy). Besides their use in the field of contraception, many non-contraceptive benefits of estroprogestins are mostly due to the activities of progestins. Pharmacological characteristics, dosage and individual metabolism could be listed among the principal aspects influencing their clinical effects.

CONCLUSIONS

The choice of each progestin according to its pharmacological profile is crucial for the appropriate management of any gynaecological condition. An aware knowledge of these compounds is fundamental to hone medical practice.

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.

Norethisterone and its acetate - what's so special about them?

INTRODUCTION

Progestogens (progestins) are widely used for contraception, in postmenopausal hormone therapy, and in treatment of abnormal uterine bleeding and endometriosis. Norethisterone (NET) and its acetate (NETA) differ from other progestogens by their partial conversion to ethinylestradiol (EE). We review their special characteristics and focus on the clinically relevant risk factors associated with estrogen action, such as migraine with aura and risk of thrombosis.

METHODS

Narrative review based on a medical literature (OvidMedline and PubMed) search.

RESULTS

NET converts to significant amounts of EE; 10-20 mg NET corresponds to 20-30 µg EE. The effects of NET on the endometrium are pronounced, making it a good choice for treating abnormal uterine bleeding, endometriosis, and endometrial hyperplasia. NET also has beneficial effects on bone mineral density and positive or neutral effects on cardiovascular health. Conversely, long-term use of NET is associated with a slightly increased breast cancer risk, and the risk of venous thromboembolism is moderately increased. This risk seems to be dose-dependent; contraceptive use carries no risk, but therapeutic doses might be associated with an increased risk. Studies suggest an association between combinations of EE and progestogens and ischaemic stroke, which in particular concerns women with migraine. No studies have, however, assessed this risk related to the therapeutic use of NET.

CONCLUSIONS

NET is a potent progestogen, especially when considering the endometrium. Its partial conversion to EE, however, is important to remember. Clinical consideration is required with women at high risk for either breast cancer or thromboembolism, or experiencing migraine with aura.

Pharmacokinetic and Pharmacodynamic Profiles of Ethinylestradiol/Norgestimate Combination or Norethindrone upon Coadministration with Elagolix 150 mg Once Daily in Healthy Premenopausal Women

Background

Two pharmacokinetic/pharmacodynamic studies were conducted to evaluate the potential drug–drug interaction between elagolix, an oral gonadotropin-releasing hormone receptor antagonist, and an oral contraceptive (ethinylestradiol [EE] 0.035 mg and norgestimate 0.18/0.215/0.25 mg) or progestin-only contraceptive (norethindrone 0.35 mg) in healthy premenopausal women.

Methods

These phase I studies used a two-period, sequential design, where period 1 included treatment with oral contraceptives, followed by period 2 with contraceptives coadministered with elagolix 150 mg once daily.

Results

In study 1, pharmacokinetic exposures for EE in period 2 increased by 30% and the norgestimate metabolites decreased by approximately 15% when coadministered with elagolix. Mean hormone exposure appeared lower for follicle-stimulating hormone (FSH; 31%), luteinizing hormone (LH; 38%), and estradiol (E2; 16%). The percentage of women with consecutive progesterone (P) concentrations above 5 nmol/L was similar in both periods. Norethindrone pharmacokinetic exposures were comparable in both periods. The hormone exposure for LH and FSH was similar, and mean E2 exposure was 32% lower in period 2. The percentage of subjects with consecutive ovulatory P concentrations was also similar in both periods (study 2). Safety and tolerability profiles were unremarkable in both studies.

Conclusions

Coadministration of elagolix 150 mg once daily with oral contraceptives containing EE and norgestimate, or norethindrone, resulted in small pharmacokinetic changes in the oral contraceptive components. Similar or lower FSH, LH, and E2 exposures were observed during coadministration, with ovulatory P concentrations also comparable in both periods. The pharmacodynamic profiles of the oral contraceptives were maintained when coadministered with elagolix.

Drug-Drug Interaction Studies With Oral Contraceptives: Pharmacokinetic/Pharmacodynamic and Study Design Considerations

Oral contraceptives (OCs) are the most widely used form of birth control among women of childbearing potential. Knowledge of potential drug-drug interactions (DDIs) with OCs becomes imperative to provide information on the medication to women of childbearing potential and enable their inclusion in clinical trials, especially if the new molecular entity is a teratogen. Although a number of DDI guidance documents are available, they do not provide recommendations for the design and conduct of OC DDI studies. The evaluation of DDI potential of a new molecular entity and OCs is particularly challenging because of the availability of a wide variety of combinations of hormonal contraceptives, different doses of the ethinyl estradiol, and different metabolic profiles of the progestin component. The aim of this review is to comprehensively discuss factors to be considered such as pharmacokinetics (PK), pharmacodynamics (PD), choice of OC, and study population for the conduct of in vivo OC DDI studies. In this context, metabolic pathways of OCs, the effect of enzyme inhibitors and inducers, the role of sex hormone-binding globulin in the PK of progestins, current evidence on OC DDIs, and the interpretation of PD end points are reviewed. With the emergence of new tools like physiologically based PK modeling, the decision to conduct an in vivo study can be made with much more confidence. This review provides a comprehensive overview of various factors that need to be considered in designing OC DDI studies and recommends PK-based DDI studies with PK end points as adequate measures to establish clinical drug interaction and measurement of PD end points when there is basis for PD interaction.

A current perspective into young female sex hormone replacement: a review

INTRODUCTION

Hormone replacement in females with hypogonadism is advocated to address the various clinical aspects of estrogen deficiency.

AREAS COVERED

This article focuses on hormone replacement in young females with hypogonadism, including a rationale as to why hormone replacement in such patients differs from treatment in postmenopausal females, a summary of symptoms encountered by females with hypogonadism and a comprehensive discussion of the various treatment options available, specifically focusing on the latest advances in the subject. A Medline search was conducted using different combinations of relevant keywords, giving preference to recent publications.

EXPERT OPINION

Whilst traditionally oral contraceptive pills (containing ethynyl estradiol) were commonly used as a form of hormone replacement, it is now increasingly recognized that this is not the optimal treatment option. Physiological hormone replacement with transdermal estradiol is found to be superior. Evidence suggests that micronized progesterone may be associated with fewer side effects, although its effect on endometrial protection is not yet proven. Synthetic progestins confer varying degrees of androgenic and thromboembolic properties which should be kept in mind when prescribing individualized treatment. Further studies in different sub-cohorts of female patients with hypogonadism might help address the specific needs of individual patients.

Progesterone - Friend or foe?

Estradiol is the "prototypic" sex hormone of women. Yet, women have another sex hormone, which is often disregarded: Progesterone. The goal of this article is to provide a comprehensive review on progesterone, and its metabolite allopregnanolone, emphasizing three key areas: biological properties, main functions, and effects on mood in women. Recent years of intensive research on progesterone and allopregnanolone have paved the way for new treatment of postpartum depression. However, treatment for premenstrual syndrome and premenstrual dysphoric disorder as well as contraception that women can use without risking mental health problems are still needed. As far as progesterone is concerned, we might be dealing with a two-edged sword: while its metabolite allopregnanolone has been proven useful for treatment of PPD, it may trigger negative symptoms in women with PMS and PMDD. Overall, our current knowledge on the beneficial and harmful effects of progesterone is limited and further research is imperative.

Ibrutinib does not have clinically relevant interactions with oral contraceptives or substrates of CYP3A and CYP2B6

Ibrutinib may inhibit intestinal CYP3A4 and induce CYP2B6 and/or CYP3A. Secondary to potential induction, ibrutinib may reduce the exposure and effectiveness of oral contraceptives (OCs). This phase I study evaluated the effect of ibrutinib on the pharmacokinetics of the CYP2B6 substrate bupropion, CYP3A substrate midazolam, and OCs ethinylestradiol (EE) and levonorgestrel (LN). Female patients (N = 22) with B‐cell malignancies received single doses of EE/LN (30/150 μg) and bupropion/midazolam (75/2 mg) during a pretreatment phase on days 1 and 3, respectively (before starting ibrutinib on day 8), and again after ibrutinib 560 mg/day for ≥ 2 weeks. Intestinal CYP3A inhibition was assessed on day 8 (single‐dose ibrutinib plus single‐dose midazolam). Systemic induction was assessed at steady‐state on days 22 (EE/LN plus ibrutinib) and 24 (bupropion/midazolam plus ibrutinib). The geometric mean ratios (GMRs; test/reference) for maximum plasma concentration (C_max) and area under the plasma concentration‐time curve (AUC) were derived using linear mixed‐effects models (90% confidence interval within 80%‐125% indicated no interaction). On day 8, the GMR for midazolam exposure with ibrutinib coadministration was ≤ 20% lower than the reference, indicating lack of intestinal CYP3A4 inhibition. At ibrutinib steady‐state, the C_max and AUC of EE were 33% higher than the reference, which was not considered clinically relevant. No substantial changes were noted for LN, midazolam, or bupropion. No unexpected safety findings were observed. A single dose of ibrutinib did not inhibit intestinal CYP3A4, and repeated administration did not induce CYP3A4/2B6, as assessed using EE, LN, midazolam, and bupropion.

Progestogens Are Metabolized by the Gut Microbiota: Implications for Colonic Drug Delivery

Following oral administration, the bioavailability of progestogens is very low and highly variable, in part due to metabolism by cytochrome P450 enzymes found in the mucosa of the small intestine. Conversely, the mucosa in the colon contains much lower levels of cytochrome P450 enzymes, thus, colonic delivery of progestogens may be beneficial. Microbiota in the colon are known to metabolize a great number of drugs, therefore, it is important to understand the stability of these hormones in the presence of colonic flora before developing formulations. The aim of this study was to investigate the stability of three progestogens: progesterone, and its two synthetic analogues, medroxyprogesterone acetate (MPA) and levonorgestrel (LNG), in the presence of human colonic microbiota. Progesterone, MPA, and LNG were incubated in mixed fecal inoculum (simulated human colonic fluid) under anerobic conditions. Progesterone was completely degraded after 2 h, whereas levels of MPA and LNG were still detectable after 24 h. The half-lives of progesterone, MPA, and LNG in fecal inoculum were 28, 644, and 240 min, respectively. This study describes the kinetics of colonic microbial metabolism of these hormones for the first time. MPA and LNG show promise for delivery to the colon, potentially improving pharmacokinetics over current oral delivery methods.

Doravirine and the Potential for CYP3A-Mediated Drug-Drug Interactions

Identifying and understanding potential drug-drug interactions (DDIs) are vital for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. This article discusses DDIs between doravirine, a nonnucleoside reverse transcriptase inhibitor (NNRTI), and cytochrome P450 3A (CYP3A) substrates and drugs that modulate CYP3A activity. Consistent with previously published in vitro data and DDI trials with the CYP3A substrates midazolam and atorvastatin, doravirine did not have any meaningful impact on the pharmacokinetics of the CYP3A substrates ethinyl estradiol and levonorgestrel. Coadministration of doravirine with CYP3A inhibitors (ritonavir or ketoconazole) increased doravirine exposure approximately 3-fold. However, these increases were not considered clinically meaningful. Conversely, previously published trials showed that coadministered CYP3A inducers (rifampin and rifabutin) decreased doravirine exposure by 88% and 50%, respectively (K. L. Yee, S. G. Khalilieh, R. I. Sanchez, R. Liu, et al., Clin Drug Investig 37:659-667, 2017 [https://doi.org/10.1007/s40261-017-0513-4]; S. G. Khalilieh, K. L. Yee, R. I. Sanchez, R. Liu, et al., J Clin Pharmacol 58:1044-1052, 2018 [https://doi.org/10.1002/jcph.1103]), while doravirine exposure following prior efavirenz administration led to an initial reduction in doravirine exposure of 62%, but the reduction became less pronounced with time (K. L. Yee, R. I. Sanchez, P. Auger, R. Liu, et al., Antimicrob Agents Chemother 61:e01757-16, 2017 [https://doi.org/10.1128/AAC.01757-16]). Overall, the coadministration of doravirine with CYP3A inhibitors and substrates is, therefore, supported by these data together with efficacy and safety data from clinical trials, while coadministration with strong CYP3A inducers, such as rifampin, cannot be recommended. Concomitant dosing with rifabutin (a CYP3A inducer less potent than rifampin) is acceptable if doravirine dosing is adjusted from once to twice daily; however, the effect of other moderate inducers on doravirine pharmacokinetics is unknown.

Degradation Kinetics and Transformation Products of Levonorgestrel and Quinestrol in Soils

Levonorgestrel (LNG) and quinestrol (QUN) are typical endocrine disruptors that enter the soil via sewage irrigation and sludge return. However, the fates of both compounds in soil are not well-understood. Laboratory microcosm studies were conducted to fill the gap of understanding of LNG and QUN behavior in soils. High values of goodness-of-fit indices (GFIs) were obtained using the double-first-order in parallel (DFOP) model and the single-first-order (SFO) model to fit the degradation kinetics of LNG and QUN in soils, respectively. The end-points (DT₅₀ and DT₉₀) of LNG and QUN were positively correlated with soil total organic carbon (TOC). Soil water content and temperature were observed to be critical factors in degradation of LNG and QUN. The degradation rates of LNG and QUN were very slow under sterile and flooded conditions, indicating that the aerobic microbial degradation was dominant in the degradation of LNG and QUN. Moreover, major transformation products were identified, and biodegradation pathways of LNG and QUN were proposed. The present study is expected to provide basic information for ecological risk assessment of LNG and QUN in the soil compartment.

Reproductive Impact of Environmental Chemicals on Animals

Wildlife is exposed to a diverse range of natural and man-made chemicals. Some environmental chemicals possess specific endocrine disrupting properties, which have the potential to disrupt reproductive and developmental process in certain animals. There is growing evidence that exposure to endocrine disrupting chemicals plays a key role in reproductive disorders in fish, amphibians, mammals, reptiles and invertebrates. This evidence comes from field-based observations and laboratory based exposure studies, which provide substantial evidence that environmental chemicals can cause adverse effects at environmentally relevant doses. There is particular concern about wildlife exposures to cocktails of biologically active chemicals, which combined with other stressors, may play an even greater role in reproductive disorders than can be reproduced in laboratory experiments. Regulation of chemicals affords some protection to animals of the adverse effects of exposure to legacy chemicals but there continues to be considerable debate on the regulation of emerging pollutants.

Development, validation and utilization of a highly sensitive LC-MS/MS method for quantification of levonorgestrel released from a subdermal implant in human plasma

Levonorgestrel (LNG) is a synthetic progestin that is available in oral contraceptive tablets, a subdermal implant, and an intrauterine system for contraception. LNG pharmacokinetics are a pivotal determinant of contraceptive efficacy and essential in assessing drug-drug interactions influencing LNG exposure following different routes of LNG administration. A highly sensitive LC-MS/MS method was developed and validated to quantify levonorgestrel in human plasma. Liquid-liquid extraction was utilized with a sample volume of 500 μL to extract levonorgestrel from plasma. Chromatographic separation of LNG was achieved with a Fortis™ C18 (3 μm: 100 mm × 2.1 mm) reverse phase analytical column. The mobile phases consisted of de-ionized water plus 0.1% NH4OH (100:0.1%, v/v) (A), and methanol plus 0.1% NH4OH (100:0.1%, v/v) (B) delivered as a gradient at a flow rate of 400 μL/min. Detection of LNG and internal standard (D-(-)-norgestrel-d7) was achieved using positive polarity mode monitoring at 313.2-245.2 amu and 320.1-251.2 amu, respectively. The assay was linear over the calibration range of 49.6 to 1500 pg/mL. This method was used to quantify plasma LNG released by subdermal implant in support of a drug interaction study among women with HIV receiving efavirenz- or nevirapine-based antiretroviral therapy.

In Vivo Formation of Ethinylestradiol After Intramuscular Administration of Norethisterone Enantate

It is known that a small fraction of orally administered norethisterone is metabolically converted to ethinylestradiol. This exploratory, open-label, nonrandomized study was conducted to investigate the systemic exposure to ethinylestradiol after intramuscular administration of norethisterone enantate in comparison with the exposure to ethinylestradiol after administration of a standard combined oral contraceptive. Sixteen healthy premenopausal women received an oral contraceptive (ethinylestradiol 30 μg/levonorgestrel 150 μg) once daily for 21 days and-after a 1-week washout period-a single intramuscular dose of 200 mg norethisterone enantate. Blood samples to determine ethinylestradiol in serum were taken over 24 hours after the last dose of ethinylestradiol/levonorgestrel and over 8 weeks after administration of norethisterone enantate. Oral equivalent doses of ethinylestradiol were estimated based on area under the concentration-time curves. The ethinylestradiol serum concentrations observed after administration of norethisterone enantate were relatively low: The mean maximum concentration was only 32% of the maximum observed after ethinylestradiol/levonorgestrel (90% confidence interval, 22.5%-44.7%). The maximum oral equivalent dose of ethinylestradiol was markedly lower than 30 μg ethinylestradiol per day (20.3 μg/day; 90% confidence interval, 14.8-28.0 μg/day). The same applied to the average oral equivalent dose of ethinylestradiol for the 8-week postdose interval (4.41 μg/day; 90% confidence interval, 3.57-5.46 μg/day). To conclude, the study results indicate that metabolic conversion of norethisterone to ethinylestradiol also occurs after intramuscular administration of 200 mg norethisterone enantate, but is associated with a lower exposure to ethinylestradiol than the use of a combined oral contraceptive containing 30 μg ethinylestradiol (plus 150 μg levonorgestrel).

The Primodos components Norethisterone acetate and Ethinyl estradiol induce developmental abnormalities in zebrafish embryos

Primodos was a hormone pregnancy test used between 1958-1978 that has been implicated with causing a range of birth defects ever since. Though Primodos is no longer used, it's components, Norethisterone acetate and Ethinyl estradiol, are used in other medications today including treatments for endometriosis and contraceptives. However, whether Primodos caused birth defects or not remains controversial, and has been little investigated. Here we used the developing zebrafish embryo, a human cell-line and mouse retinal explants to investigate the actions of the components of Primodos upon embryonic and tissue development. We show that Norethisterone acetate and Ethinyl estradiol cause embryonic damage in a dose and time responsive manner. The damage occurs rapidly after drug exposure, affecting multiple organ systems. Moreover, we found that the Norethisterone acetate and Ethinyl estradiol mixture can affect nerve outgrowth and blood vessel patterning directly and accumulates in the forming embryo for at least 24 hrs. These data demonstrate that Norethisterone acetate and Ethinyl estradiol are potentially teratogenic, depending on dose and embryonic stage of development in the zebrafish. Further work in mammalian model species are now required to build on these findings and determine if placental embryos also are affected by synthetic sex hormones and their mechanisms of action.

Effect of Efavirenz on Endogenous Progesterone Concentrations and Contraceptive Outcomes among Ugandan HIV Infected Women Coadministering Ethinylestradiol/Levonorgestrel

This study assessed the effect of efavirenz mid-dose plasma concentrations on mid-luteal endogenous progesterone concentrations and contraceptive outcomes among 49 HIV infected women coadministering ethinylestradiol/levonorgestrel, including 34 HIV positive women on Highly Active Antiretroviral Therapy (HAART) and 15 HAART naïve HIV infected women, purposively selected from Mulago Hospital, Uganda. A blood sample was collected once between days 20 and 22 of each woman's menstrual cycle for measuring endogenous progesterone and efavirenz concentrations by electrochemiluminescence technology and High Performance Liquid Chromatography (HPLC), respectively. Descriptive statistical analysis and correlation and logistic regression analysis were done using SPSS v.21 and R3.1. Efavirenz showed a weak positive linear relationship with endogenous progesterone at efavirenz concentrations below 12 μg/ml. Based on serum endogenous progesterone, the observed hormonal contraceptives failure rate (24.5%) was higher than expected (maximum 8%). A higher proportion of HIV positive women on efavirenz based HAART (26.5%) was at risk of contraceptive failure than their HIV infected HAART naïve counterparts (20%) though it was not statistically significant (p = 0.63). Efavirenz mid-dose plasma concentrations seem to have no significant effect on mid-luteal endogenous progesterone concentrations and contraceptive outcomes among HIV infected Ugandan women coadministering ethinylestradiol/levonorgestrel oral pills.

Progestins used in endocrine therapy and the implications for the biosynthesis and metabolism of endogenous steroid hormones

Steroidogenesis refers to the de novo synthesis of steroid hormones from cholesterol by a number of sequential enzyme catalysed reactions in the adrenal and the gonads. In addition, circulating steroid hormone precursors are further metabolised in selected peripheral tissues. It has been suggested that the biosynthesis of endogenous steroid hormones can be modulated by progestins, used widely by women in female reproductive medicine. However, as a number of structurally diverse progestins with different pharmacological properties are available, it is possible that these synthetic compounds may vary in their effects on steroidogenesis. This review summarises the evidence indicating that progestins influence the biosynthesis of steroid hormones in the adrenal and gonads, as well as the metabolism of these endogenous hormones in the breast, highlighting the limitations to the current knowledge and directions for future research.

Concentrations of levonorgestrel and ethinylestradiol in wastewater effluents: Is the progestin also cause for concern?

Synthetic hormones have been widely reported in treated sewage effluents, and consequently receiving aquatic environments. Ethinylestradiol (EE2) is a potent synthetic estrogen commonly used in conjunction with levonorgestrel in oral contraceptive pills. Both EE2 and levonorgestrel have been identified in the aquatic environment, but although there is a significant amount of literature on EE2, there is much less information on levonorgestrel. Using Australian prescription data as well as excretion and predicted wastewater removal rates, the concentrations of EE2 and levonorgestrel in Australian wastewater were calculated at 0.1 ng/L to 0.5 ng/L and 0.2 ng/L to 0.6 ng/L, respectively. Both compounds were analyzed in treated wastewater and surface water grab samples from 3 Southeast Queensland, Australia sites. The predicted no-effect concentration (PNEC) for EE2 of 0.1 ng/L was exceeded at most sites, with EE2 concentrations up to 2 ng/L in treated effluent, albeit quickly diluted to 0.1 ng/L to 0.2 ng/L in the receiving environment. A provisional PNEC for levonorgestrel of 0.1 ng/L derived in the present study was slightly lower than predicted effluent concentrations of 0.2 ng/L to 0.6 ng/L, indicating a potential risk of endocrine-related effects in exposed aquatic species. The detection limit for levonorgestrel in the present study was 2.5 ng/L, and all samples were below detection limit. The present study's results suggest that improvements in analytical capabilities for levonorgestrel are warranted to more accurately quantify the risk of this compound in the receiving environment. Environ Toxicol Chem 2016;35:1378-1385. © 2015 SETAC.

Ethynilestradiol 20 mcg plus Levonorgestrel 100 mcg: Clinical Pharmacology

Estroprogestins (EPs) are combinations of estrogen and progestin with several actions on women's health. The different pharmacological composition of EPs is responsible for different clinical effects. One of the most used low-dose EP associations is ethinylestradiol 20 mcg plus levonorgestrel 100 mcg in monophasic regimen (EE20/LNG100). This review summarizes clinical pharmacology, cycle control, and effects on lipid and glucose metabolism, coagulation, body weight/body composition, acne, and sexuality of EE20/LNG100. Overall, EE20/LNG100 combination is safe and well tolerated, and in several studies the incidence of adverse events in the treated group was comparable to that of the placebo group. Cycle control was effective and body weight/body composition did not vary among treated and untreated groups in most studies. The EE20/LNG100 combination shows mild or no effect on lipid and glucose metabolism. Lastly, EE20/LNG100 is associated with a low risk of venous thromboembolism (VTE). In conclusion, in the process of decision making for the individualization of EPs choice, EE20/LNG100 should be considered for its favorable clinical profile.

A comparative study of the androgenic properties of progesterone and the progestins, medroxyprogesterone acetate (MPA) and norethisterone acetate (NET-A)

The importance of investigating the molecular mechanism of action of medroxyprogesterone acetate (MPA) and norethisterone acetate (NET-A), two clinically important progestins used in hormone therapy (HT), has been highlighted by clinical evidence showing that MPA and norethisterone (NET) increase the risk of the development of breast cancer in HRT users, and that MPA may increase susceptibility to- and transmission of HIV-1. The aim of this study was to compare the molecular mechanisms of action of MPA, NET-A and progesterone (Prog) via the androgen receptor (AR) in a cell line model that can minimize confounding factors such as the presence of other steroid receptors. This study is the first to determine accurate apparent Ki values for Prog, MPA and NET-A toward the human AR in COS-1 cells. The results reveal that these ligands have a similar binding affinity for the AR to that of the natural androgen 5α-dihydrotestosterone (DHT) (Ki's for DHT, Prog, MPA and NET-A are 29.4, 36.6, 19.4 and 21.9 nM, respectively). Moreover, in both transactivation and transrepression transcriptional assays we demonstrate that, unlike Prog, MPA and NET-A are efficacious AR agonists, with activities comparable to DHT. One of the most novel findings of our study is that NET-A, like DHT, induces the ligand-dependent interaction between the NH2- and COOH-terminal domains (N/C-interaction) of the AR independent of promoter-context, while MPA does not induce the N/C interaction on a classical ARE and does so only weakly on an AR-selective ARE. This suggests that MPA and NET-A may exert differential promoter-specific actions via the AR in vivo. Consistent with this, molecular modeling suggests that MPA and NET-A induce subtle differences in the structure of the AR ligand binding domain. Taken together, the results from this study suggest that unlike Prog, both MPA and NET-A used in hormonal therapy are likely to compete with DHT and exert significant and promoter-specific off-target transcriptional effects via the AR, possibly contributing to some of the observed side-effects with the clinical use of MPA and NET-A.

Clinical drug-drug interaction assessment of ivacaftor as a potential inhibitor of cytochrome P450 and P-glycoprotein

Ivacaftor is approved in the USA for the treatment of cystic fibrosis (CF) in patients with a G551D-CFTR mutation or one of eight other CFTR mutations. A series of in vitro experiments conducted early in the development of ivacaftor indicated ivacaftor and metabolites may have the potential to inhibit cytochrome P450 (CYP) 2C8, CYP2C9, CYP3A, and CYP2D6, as well as P-glycoprotein (P-gp). Based on these results, a series of clinical drug-drug interaction (DDI) studies were conducted to evaluate the effect of ivacaftor on sensitive substrates of CYP2C8 (rosiglitazone), CYP3A (midazolam), CYP2D6 (desipramine), and P-gp (digoxin). In addition, a DDI study was conducted to evaluate the effect of ivacaftor on a combined oral contraceptive, as this is considered an important comedication in CF patients. The results indicate ivacaftor is a weak inhibitor of CYP3A and P-gp, but has no effect on CYP2C8 or CYP2D6. Ivacaftor caused non-clinically significant increases in ethinyl estradiol and norethisterone exposure. Based on these results, caution and appropriate monitoring are recommended when concomitant substrates of CYP2C9, CYP3A and/or P-gp are used during treatment with ivacaftor, particularly drugs with a narrow therapeutic index, such as warfarin.

Medical treatments for endometriosis-associated pelvic pain

The main sequelae of endometriosis are represented by infertility and chronic pelvic pain. Chronic pelvic pain causes disability and distress with a very high economic impact. In the last decades, an impressive amount of pharmacological agents have been tested for the treatment of endometriosis-associated pelvic pain. However, only a few of these have been introduced into clinical practice. Following the results of the controlled studies available, to date, the first-line treatment for endometriosis associated pain is still represented by oral contraceptives used continuously. Progestins represent an acceptable alternative. In women with rectovaginal lesions or colorectal endometriosis, norethisterone acetate at low dosage should be preferred. GnRH analogues may be used as second-line treatment, but significant side effects should be taken into account. Nonsteroidal anti-inflammatory drugs are widely used, but there is inconclusive evidence for their efficacy in relieving endometriosis-associated pelvic pain. Other agents such as GnRH antagonist, aromatase inhibitors, immunomodulators, selective progesterone receptor modulators, and histone deacetylase inhibitors seem to be very promising, but there is not enough evidence to support their introduction into routine clinical practice. Some other agents, such as peroxisome proliferator activated receptors-γ ligands, antiangiogenic agents, and melatonin have been proven to be efficacious in animal studies, but they have not yet been tested in clinical studies.

The injectable-only contraceptive medroxyprogesterone acetate, unlike norethisterone acetate and progesterone, regulates inflammatory genes in endocervical cells via the glucocorticoid receptor

Clinical studies suggest that the injectable contraceptive medroxyprogesterone acetate (MPA) increases susceptibility to infections such as HIV-1, unlike the injectable contraceptive norethisterone enanthate (NET-EN). We investigated the differential effects, molecular mechanism of action and steroid receptor involvement in gene expression by MPA as compared to NET and progesterone (P4) in the End1/E6E7 cell line model for the endocervical epithelium, a key point of entry for pathogens in the female genital mucosa. MPA, unlike NET-acetate (NET-A) and P4, increases mRNA expression of the anti-inflammatory GILZ and IκBα genes. Similarly, MPA unlike NET-A, decreases mRNA expression of the pro-inflammatory IL-6, IL-8 and RANTES genes, and IL-6 and IL-8 protein levels. The predominant steroid receptor expressed in the End1/E6E7 and primary endocervical epithelial cells is the glucocorticoid receptor (GR), and GR knockdown experiments show that the anti-inflammatory effects of MPA are mediated by the GR. Chromatin-immunoprecipitation results suggest that MPA, unlike NET-A and P4, represses pro-inflammatory cytokine gene expression in cervical epithelial cells via a mechanism involving recruitment of the GR to cytokine gene promoters, like the GR agonist dexamethasone. This is at least in part consistent with direct effects on transcription, without a requirement for new protein synthesis. Dose response analysis shows that MPA has a potency of ∼24 nM for transactivation of the anti-inflammatory GILZ gene and ∼4–20 nM for repression of the pro-inflammatory genes, suggesting that these effects are likely to be relevant at injectable contraceptive doses of MPA. These findings suggest that in the context of the genital mucosa, these GR-mediated glucocorticoid-like effects of MPA in cervical epithelial cells are likely to play a critical role in discriminating between the effects on inflammation caused by different progestins and P4 and hence susceptibility to genital infections, given the predominant expression of the GR in primary endocervical epithelial cells.

Effect of protease inhibitors on steady-state pharmacokinetics of oral norethindrone contraception in HIV-infected women

OBJECTIVE

Pharmacokinetic interactions exist between combined oral contraceptives and protease inhibitors (PI). However, such information is lacking for progestin-only oral contraception. We sought to define the steady-state pharmacokinetic interaction between norethindrone (NET) and PI in HIV-infected women.

METHODS AND DESIGN

We conducted an open-label, prospective, nonrandomized trial to characterize the steady-state pharmacokinetics of serum NET in HIV-infected women receiving PI compared with a control group of HIV-infected women receiving other noninteracting drugs. After 21 days of 0.35 mg of NET ingestion once daily, serial serum samples were obtained at 0, 1, 2, 3, 4, 6, 8, 12, 24, 48, and 72 hours. The area under the curve between 0 and 72 hours after ingestion was calculated by trapezoidal approximation.

RESULTS

Thirty-five women were enrolled, 2 withdrew. Sixteen women in the PI group and 17 controls completed the study. NET half-life and maximum concentration were not significantly different between the 2 groups. Minimum concentration of NET was significantly higher in the PI group (P = 0.01). The ratio of the geometric mean NET area under the curve in the PI group compared with controls was 1.5 (90% confidence interval: 1.21 to 1.86). NET serum concentrations were significantly higher in HIV-infected women taking a PI compared with controls (P = 0.004).

CONCLUSIONS

Coadministration of PI inhibits NET metabolism as shown by higher serum NET area under the curve levels, a surrogate marker for therapeutic contraceptive efficacy. This study supports the increased utilization of progestin-only pills in HIV-infected women receiving certain PI regimens.

Effect of eslicarbazepine acetate on the pharmacokinetics of a combined ethinylestradiol/levonorgestrel oral contraceptive in healthy women

OBJECTIVE

To investigate the effect of once-daily (QD) eslicarbazepine acetate (ESL) 800 mg and 1,200 mg administration on pharmacokinetics of a combined ethinylestradiol/levonorgestrel oral contraceptive (OC) in women of childbearing potential.

METHODS

Two two-way, crossover, two-period, randomized, open-label studies were performed in 20 healthy female subjects, each. In one period (ESL+OC period), subjects received ESL 800 mg QD in one study and ESL 1200 mg QD in the other study, for 15 days; concomitantly with the Day 14 ESL dose, an oral single dose of 30 μg ethinylestradiol and 150 μg levonorgestrel was administered. In the other period (OC alone), a single dose of 30 μg ethinylestradiol and 150 μg levonorgestrel was administered. Three weeks or more separated the periods. An analysis of variance (ANOVA) was used to test for differences between pharmacokinetic parameters of 30 μg ethinylestradiol and 150 μg levonorgestrel following ESL+OC and OC alone, and 90% confidence intervals (90%CI) for the ESL+OC/OC alone geometric mean ratio (GMR) were calculated.

RESULTS

ESL significantly decreased the systemic exposure to both ethinylestradiol and levonorgestrel. GMR (90%CI) for AUC0-24 of ethinylestradiol were 68% (64%; 71%) following 1,200 mg ESL and 75% (71%; 79%) following 800 mg ESL. GMR (90%CI) for AUC0-24 of levonorgestrel were 76% (68%; 86%) following 1,200 mg ESL and 89% (82%; 97%) following 800 mg ESL.

CONCLUSIONS

A clinically relevant dose-dependent effect of ESL administration on the pharmacokinetics of ethinylestradiol and levonorgestrel was observed. Therefore, to avoid inadvertent pregnancy, women of childbearing potential should use other adequate methods of contraception during treatment with ESL, and, in case ESL treatment is discontinued, until CYP3A4 activity returns to normal.

Progestogens used in postmenopausal hormone therapy: differences in their pharmacological properties, intracellular actions, and clinical effects

The safety of progestogens as a class has come under increased scrutiny after the publication of data from the Women's Health Initiative trial, particularly with respect to breast cancer and cardiovascular disease risk, despite the fact that only one progestogen, medroxyprogesterone acetate, was used in this study. Inconsistency in nomenclature has also caused confusion between synthetic progestogens, defined here by the term progestin, and natural progesterone. Although all progestogens by definition have progestational activity, they also have a divergent range of other properties that can translate to very different clinical effects. Endometrial protection is the primary reason for prescribing a progestogen concomitantly with postmenopausal estrogen therapy in women with a uterus, but several progestogens are known to have a range of other potentially beneficial effects, for example on the nervous and cardiovascular systems. Because women remain suspicious of the progestogen component of postmenopausal hormone therapy in the light of the Women's Health Initiative trial, practitioners should not ignore the potential benefits to their patients of some progestogens by considering them to be a single pharmacological class. There is a lack of understanding of the differences between progestins and progesterone and between individual progestins differing in their effects on the cardiovascular and nervous systems, the breast, and bone. This review elucidates the differences between the substantial number of individual progestogens employed in postmenopausal hormone therapy, including both progestins and progesterone. We conclude that these differences in chemical structure, metabolism, pharmacokinetics, affinity, potency, and efficacy via steroid receptors, intracellular action, and biological and clinical effects confirm the absence of a class effect of progestogens.

Role of the levonorgestrel intrauterine system in effective contraception

Norgestrel, a synthetic progestin chemically derived from 19-nortestosterone, is six times more potent than progesterone, with variable binding affinity to various steroid receptors. The levonorgestrel-releasing intrauterine system (LNG IUS) provides a long-acting, highly effective, and reversible form of contraception, with a pearl index of 0.18 per 100 women-years. The locally released hormone leads to endometrial concentrations that are 200-800 times those found after daily oral use and a plasma level that is lower than that with other forms of levonorgestrel-containing contraception. The contraceptive effect of the LNG IUS is achieved mainly through its local suppressive effect on the endometrium, leading to endometrial thinning, glandular atrophy, and stromal decidualization without affecting ovulation. The LNG IUS is generally well tolerated. The main side effects are related to its androgenic activity, which is usually mild and transient, resolving after the first few months. Menstrual abnormalities are also common but well tolerated, and even become desirable (eg, amenorrhea, hypomenorrhea, and oligomenorrhea) with proper counseling of the patient during the choice of the method of contraception. The satisfaction rates after 3 years of insertion are high, reaching between 77% and 94%. The local effect of the LNG IUS on the endometrium and low rates of systemic adverse effects have led to its use in other conditions rather than contraception, as for the treatment of endometrial hyperplasia, benign menorrhagia, endometriosis, adenomyosis, and uterine fibroids.

Effect of the ethinylestradiol/levonorgestrel combined oral contraceptive on the activity of cytochrome P4503A in obese women

AIM(S)

While it is known that CYP3A4/5 activity is decreased with combined oral contraceptive (COC) use and obesity suppresses CYP expression, the combined effects of obesity and COC use on CYP3A4/5 activity are unclear. Therefore, our aim was to examine the effect of COC usage on CYP3A4/5 activity in obese women.

METHODS

Thirty-four, obese (body mass index, BMI > 30 kg m(-2)) women of reproductive age (18-35 years old) were placed on a COC pill containing 20 µg ethinylestradiol/100 µg levonorgestrel for 21 days starting at the onset of menses. A midazolam pharmacokinetic study was conducted prior to initiation and after 21 days of COC treatment. Serial blood samples were collected and plasma concentrations of midazolam were measured using liquid chromatography tandem mass spectrometry. Pharmacokinetic parameters were estimated using a non-compartmental method.

RESULTS

Midazolam clearance, a surrogate measure of CYP3A4/5 activity, was significantly decreased upon COC use (63.3 l h(-1) vs. 53.9 l h(-1), P < 0.05). A median decrease of 5.6 l h(-1) (95% CI -4.1, 13.3 l h(-1)) was observed. However, the magnitude of change was similar to that reported in women with normal BMI.

CONCLUSIONS

Although we hypothesized that obesity might amplify the impact on CYP3A4/5 activity in COC users, we found that this was not the case. This finding is reassuring regarding potential additional drug-drug interactions in obese COC users as CYP3A4/5 is a major enzyme in the metabolism of many marketed drugs.

Impact of obesity on drug metabolism and elimination in adults and children

The prevalence of obesity in adults and children is rapidly increasing across the world. Several general (patho)physiological alterations associated with obesity have been described, but the specific impact of these alterations on drug metabolism and elimination and its consequences for drug dosing remains largely unknown. In order to broaden our knowledge of this area, we have reviewed and summarized clinical studies that reported clearance values of drugs in both obese and non-obese patients. Studies were classified according to their most important metabolic or elimination pathway. This resulted in a structured review of the impact of obesity on metabolic and elimination processes, including phase I metabolism, phase II metabolism, liver blood flow, glomerular filtration and tubular processes. This literature study shows that the influence of obesity on drug metabolism and elimination greatly differs per specific metabolic or elimination pathway. Clearance of cytochrome P450 (CYP) 3A4 substrates is lower in obese as compared with non-obese patients. In contrast, clearance of drugs primarily metabolized by uridine diphosphate glucuronosyltransferase (UGT), glomerular filtration and/or tubular-mediated mechanisms, xanthine oxidase, N-acetyltransferase or CYP2E1 appears higher in obese versus non-obese patients. Additionally, in obese patients, trends indicating higher clearance values were seen for drugs metabolized via CYP1A2, CYP2C9, CYP2C19 and CYP2D6, while studies on high-extraction-ratio drugs showed somewhat inconclusive results. Very limited information is available in obese children, which prevents a direct comparison between data obtained in obese children and obese adults. Future clinical studies, especially in children, adolescents and morbidly obese individuals, are needed to extend our knowledge in this clinically important area of adult and paediatric clinical pharmacology.

Metabolism of the synthetic progestogen norethynodrel by human ketosteroid reductases of the aldo-keto reductase superfamily

Human ketosteroid reductases of the aldo-keto reductase (AKR) superfamily, i.e. AKR1C1-4, are implicated in the biotransformation of synthetic steroid hormones. Norethynodrel (NOR, 17α-ethynyl-17β-hydroxy-estra-5(10)-en-3-one), the progestin component of the first marketed oral contraceptive, is known to undergo rapid and extensive metabolism to 3α- and 3β-hydroxymetabolites. The ability of the four human AKR1C enzymes to catalyze the metabolism of NOR has now been characterized. AKR1C1 and AKR1C2 almost exclusively converted NOR to 3β-hydroxy NOR, while AKR1C3 gave 3β-hydroxy NOR as the main product and AKR1C4 predominantly formed 3α-hydroxy NOR. Individual AKR1C enzymes also displayed distinct kinetic properties in the reaction of NOR. In contrast, norethindrone (NET), the Δ(4)-isomer of NOR and the most commonly used synthetic progestogen, was not a substrate for the AKR1C enzymes. NOR is also structurally identical to the hormone replacement therapeutic tibolone (TIB), except TIB has a methyl group at the 7α-position. Product profiles and kinetic parameters for the reduction of NOR catalyzed by each individual AKR1C isoform were identical to those for the reduction of TIB catalyzed by the respective isoform. These data suggest that the presence of the 7α-methyl group has a minimal effect on the stereochemical outcome of the reaction and kinetic behavior of each enzyme. Results indicate a role of AKR1C in the hepatic and peripheral metabolism of NOR to 3α- and 3β-hydroxy NOR and provide insights into the differential pharmacological properties of NOR, NET and TIB.

Differential regulation of endogenous pro-inflammatory cytokine genes by medroxyprogesterone acetate and norethisterone acetate in cell lines of the female genital tract

BACKGROUND

Medroxyprogesterone acetate (MPA) and norethisterone (NET) and its derivatives are widely used in female reproductive therapy, but little is known about their mechanisms of action via steroid receptors in the female genital tract. MPA used as a contraceptive has been implicated in effects on local immune function. However, the relative effects of progesterone (Prog), MPA and norethisterone acetate (NET-A) on cytokine gene expression in the female genital tract are unknown.

STUDY DESIGN

Using two epithelial cell lines generated from normal human vaginal (Vk2/E6E7) and ectocervical (Ect1/E6E7) cells as in vitro cell culture model systems for mucosal immunity of the female cervicovaginal environment, we investigated steroid receptor expression and activity as well as regulation of cytokine/chemokine genes by MPA and NET-A, as compared to the endogenous hormone Prog.

RESULTS

We show that the Prog, androgen, glucocorticoid and estrogen receptors (PR, AR, GR and ER, respectively) are expressed in both the Vk2/E6E7 and Ect1/E6E7 cell lines, and that the GR and AR are transcriptionally active. This study is the first to show ligand-, promoter- and cell-specific regulation of IL-6, IL-8 and RANTES (regulated-upon-activation, normal T cell expressed and secreted) gene expression by Prog, MPA and NET-A in these cell lines. Moreover, we show that the repression of the TNF-α-induced RANTES gene by MPA in the Ect1/E6E7 cell line is mediated by the AR.

CONCLUSION

Collectively, these data demonstrate that cell lines from different anatomical sites of the female genital tract respond differently to Prog and the synthetic progestins, most likely due to differential actions via different steroid receptors. The results highlight the importance of choice of progestins for immune function in the cervicovaginal environment. They further suggest that choice of progestins in endocrine therapy may have implications for women's risk of susceptibility to infections due to differential actions on genes involved in inflammation and immune function.

Effect of ticagrelor on the pharmacokinetics of ethinyl oestradiol and levonorgestrel in healthy volunteers

BACKGROUND

Cytochrome P450 3 A is involved in ticagrelor and ethinyl oestradiol/levonorgestrel metabolism; so a potential drug-drug interaction may occur.

OBJECTIVES

To assess: ticagrelor effects on ethinyl oestradiol/levonorgestrel pharmacokinetics, endogenous sex hormone levels; ethinyl oestradiol/levonorgestrel effects on ticagrelor pharmacokinetics; tolerability of ticagrelor + ethinyl oestradiol/levonorgestrel.

METHODS

This trial was a randomized, double-blind, two-way crossover, single-center study. Twenty-two healthy female volunteers (on stable ethinyl oestradiol/levonorgestrel) received 90 mg ticagrelor or placebo twice daily with ethinyl oestradiol/levonorgestrel (0.03 mg/0.15 mg; Nordette) on cycle days 1-21. Volunteers crossed over treatment on day 1/cycle 2. Pharmacokinetic parameters were evaluated on cycle day 21, and endogenous hormones assayed on cycle days 1, 7, 14 and 21.

CLINICAL TRIAL REGISTRATION NUMBER

NCT006895906.

RESULTS

Ethinyl oestradiol absorption was rapid (median t(max) approximately 1 hour), and was not affected by ticagrelor. Ticagrelor co-administration (90% confidence interval [CI]) increased AUC(0-τ), C(min), and C(max) of ethinyl oestradiol by 20% (1.03-1.40), 20% (0.96-1.50) and 31% (1.18-1.44), respectively. Ticagrelor had no effect on levonorgestrel pharmacokinetic parameters versus placebo (90% CI: AUC(0-τ) 0.97-1.10; C(min) 0.94-1.10; C(max) 1.02-1.16). Steady-state ticagrelor, and AR-C124910XX (major and equally pharmacologically active metabolite), AUC(0-τ), C(max), and t(max) were comparable with published findings. Pre-dose ticagrelor and AR-C124910XX plasma concentrations were higher on cycle day 21 versus days 7 and 14. Endogenous sex hormone plasma levels were unaffected by ticagrelor. Co-administration of ticagrelor with ethinyl oestradiol/levonorgestrel was well tolerated. Study limitations included: no ticagrelor-only arm; only one type of oral contraceptive; short study duration; using oestradiol/levonorgestrel pharmacokinetic parameters as surrogate marker for contraceptive efficacy.

CONCLUSIONS

Ticagrelor co-administration with ethinyl oestradiol/levonorgestrel increased ethinyl oestradiol exposure by approximately 20%, with no effect on levonorgestrel pharmacokinetics. No clinically relevant effect on contraceptive efficacy is expected with ethinyl oestradiol/levonorgestrel and ticagrelor co-administration.

Molecular effects and bioaccumulation of levonorgestrel in the non-target organism Dreissena polymorpha

Bioaccumulation and effects of the contraceptive hormone levonorgestrel were examined in the non-target organism Dreissena polymorpha. Molecular biomarkers of biotransformation, elimination, antioxidant defence and protein damage were analyzed after exposure to increasing concentrations of levonorgestrel in a flow-through system. The lowest concentration (0.312 μg L(-1)) was 100-fold bioconcentrated within four days. A decrease of the bioconcentration factor was observed within one week for the highest test concentrations (3.12 and 6.24 μg L(-1)) suggesting enhanced excretory processes. The immediate mRNA up-regulation of pi class glutathione S-transferase proved that phase II biotransformation processes were induced. Disturbance of fundamental cell functions was assumed since the aryl hydrocarbon receptor has been permanently down-regulated. mRNA up-regulation of P-glycoprotein, superoxide dismutase and metallothioneine suggested enhanced elimination processes and ongoing oxidative stress. mRNA up-regulation of heat shock protein 70 in mussels exposed to the two highest concentrations clearly indicated impacts on protein damage.

Progestagens for human use, exposure and hazard assessment for the aquatic environment

Little information is available on the environmental occurrence and ecotoxicological effects of pharmaceutical gestagens released in the aquatic environment. Since eighteen different gestagens were found to be used in France, preliminary exposure and hazard assessment were done. Predicted environmental concentrations (PECs) suggest that if parent gestagens are expected to be found in the ng l(-1) range, some active metabolites could be present at higher concentrations, although limited data on metabolism and environmental fate limit the relevance of PECs. The biological effects are not expected to be restricted to progestagenic activity. Both anti-androgenic activity (mainly for cyproterone acetate, chlormadinone acetate and their metabolites) and estrogenic activity (mainly for reduced metabolites of levonorgestrel and norethisterone) should also occur. All these molecules are likely to have a cumulative effect among themselves or with other xenoestrogens. Studies on occurrence, toxicity and degradation time are therefore needed for several of these compounds.

Safety, efficacy and patient satisfaction with continuous daily administration of levonorgestrel/ethinylestradiol oral contraceptives

The progestational steroid norgestrel was synthesized and tested between 1960 and 1965 through an international cooperation between Wyeth, USA and Schering, Berlin. It is a mixture of two "enantiomers," with only one form (designated as levonorgestrel) biologically active. When taken orally, it is rapidly absorbed, not subjected to a "first-pass" effect and is approximately 90% bioavailable, with a circulating half-life around 15 hours. Its contraceptive action is exerted at the central (hypothalamic) and peripheral (cervical mucus and endometrium) levels. Levonorgestrel (LNG), alone or in combination with ethinyl estradiol (EE), is the most widely employed contraceptive progestin: it is used in combined oral contraceptives, progestogen-only pills, long-acting contraceptive implants, intrauterine contraceptive systems and in emergency contraception. It is also the steroid of choice for new oral contraceptive regimens aimed at reducing the frequency of bleeding episodes. This novel approach, already tried more than 30 years ago, gained interest around the year 2000 when surveys of women's attitudes toward monthly menstrual bleeding started to show a major change: more and more women declared that they would welcome a hormonal contraceptive method that reduced bleeding episodes to 4, 2 or even 1 per year. At this point, while the debate on the significance and "usefulness" of menstruation went on, attention focused on new regimens. The first new modality consisted of changing the 7-day medication-free interval, either shortening it to fewer than 7 days, or by the administration of low-dose estrogens during the interval between packages. Then, continuous administration regimens started to be investigated. This, however, did not happen suddenly, since, in specific situations, doctors had for years empirically utilized various continuous administration regimens. The first extended-cycle oral contraceptive regimen introduced in clinical practice is an 84-day regimen that results in bleeding only 4 times a year. A commercial product specifically packed for continuous use is now available in Europe and contains 30 mug EE and 150 mug LNG. In a variation of this regimen, after administration of the same combination for 84 days, women are given 7 pills containing 10 mug EE. A 6-monthly regimen has also been tested in a small study using EE 20 mug plus LNG 100 mug taken with and without a hormone-free interval. Women in the continuous group reported significantly fewer bleeding days requiring protection and were more likely to have amenorrhea; in addition they also reported significantly fewer days of bloating and menstrual pain. A yearly regimen is now being developed. Each pill of this novel formulation contains EE 20 mug and LNG 90 mug to be taken continuously for 364 days (13 cycles) per year. A phase III trial has now evaluated safety, efficacy and menses inhibition. At the end of the 1-year trial amenorrhea was present in 58.7% of the women and a complete absence of bleeding in 79.0%. Overall, the number of bleeding and spotting days per pill pack declined with time and adverse events and discontinuations were comparable to those reported for cyclic oral contraceptive regimens.