Pharmacokinetics of levonorgestrel and ethinylestradiol in 9 women who received a low-dose oral contraceptive over a treatment period of 3 months and, after a wash-out phase, a single oral administration of the same contraceptive formulation

A Physiologically-Based Pharmacokinetic Simulation to Evaluate Approaches to Mitigate Efavirenz-Induced Decrease in Levonorgestrel Exposure with a Contraceptive Implant

Background: Levonorgestrel implant is a highly effective hormonal contraceptive, but its efficacy may be compromised when used with cytochrome enzyme inducers such as efavirenz. The primary aim of this study was to evaluate methods of mitigating the drug interaction. Methods: Using a physiologically-based pharmacokinetic (PBPK) model for levonorgestrel that we developed within the Simcyp® program, we evaluated a higher dose of levonorgestrel implant, a lower dose of efavirenz, and the combination of both, as possible methods to mitigate the interaction. In addition, we investigated the impact on levonorgestrel total and unbound concentrations of other events likely to be associated with efavirenz coadministration: changes in plasma protein binding of levonorgestrel (as with displacement) and high variability of efavirenz exposure (as with genetic polymorphism of its metabolism). The range of fraction unbound tested was 0.6% to 2.6%, and the range of efavirenz exposure ranged from the equivalent of 200 mg to 4800 mg doses. Results: Levonorgestrel plasma concentrations at any given time with a standard 150 mg implant dose are predicted to be approximately 68% of those of control when given with efavirenz 600 mg and 72% of control with efavirenz 400 mg. With double-dose levonorgestrel, the predictions are 136% and 145% of control, respectively. A decrease in levonorgestrel plasma protein binding is predicted to primarily decrease total levonorgestrel plasma concentrations, whereas higher efavirenz exposure is predicted to decrease total and unbound concentrations. Conclusions: Simulations suggest that doubling the dose of levonorgestrel, particularly in combination with 400 mg daily efavirenz, may mitigate the drug interaction. Changes in levonorgestrel plasma protein binding and efavirenz genetic polymorphism may help explain differences between model predictions and clinical data but need to be studied further.

The hormonal profile in women using combined monophasic oral contraceptive pills varies across the pill cycle: a temporal analysis of serum endogenous and exogenous hormones using liquid chromatography with tandem mass spectroscopy

Oral contraceptive pills, of all types, are used by approximately 151 million women worldwide; however, a clear understanding of the concentrations of endogenous and exogenous hormones across a 28-day combination monophasic oral contraceptive pill pack is not well described. In our study of 14 female participants taking various combination monophasic oral contraceptive pills, we found significant fluctuations in endogenous and exogenous hormone levels throughout the pill cycle. Our analysis revealed significantly greater levels of ethinyl estradiol on the 20th and 21st days of active pill ingestion, compared with days 1-2 (active) and days 27-28 (inactive pill ingestion). Conversely, estradiol concentrations decreased during active pill consumption, while progestin and progesterone levels remained stable. During the 7 days of inactive pill ingestion, estradiol levels rose sharply and were significantly higher at days 27-28 compared with the mid and late active phase time points, while ethinyl estradiol declined and progestin did not change. These findings challenge the previous assumption that endogenous and exogenous hormones are stable throughout the 28-day pill cycle.NEW & NOTEWORTHY The results from this study have wide-ranging implications for research and treatment in women's health including considerations in research design and interpretation for studies including women taking oral contraceptives, the potential for more precise and personalized methods of dosing to reduce unwanted side effects and adverse events, and the potential treatment of a variety of disorders ranging from musculoskeletal to neurological with exogenous hormones.

Hormonal contraception and cognition: Considering the influence of endogenous ovarian hormones and genes for clinical translation

Despite the well-known influence of ovarian hormones on the brain and widespread use of hormonal contraception (HC) since the 1960s, our knowledge of HC's cognitive effects remains limited. To date, the cognitive findings have been inconsistent. In order to establish what might make HC studies more consistent, we surveyed the literature on HCs and cognition to determine whether studies considered HC formulation, phase, pharmacokinetics, duration, and gene interactions, and assessed whether oversight of these factors might contribute to variable findings. We found that synthetic HC hormones exert dose-dependent effects, the day of oral contraceptive (Pill) ingestion is critical for understanding cognitive changes, and gene-cognition relationships differ in women taking the Pill likely due to suppressed endogenous hormones. When these factors were overlooked, results were not consistent. We close with recommendations for research more likely to yield consistent findings and be therefore, translatable.

Progesterone and contraceptive progestin actions on the brain: A systematic review of animal studies and comparison to human neuroimaging studies

In this review we systematically summarize the effects of progesterone and synthetic progestins on neurogenesis, synaptogenesis, myelination and six neurotransmitter systems. Several parallels between progesterone and older generation progestin actions emerged, suggesting actions via progesterone receptors. However, existing results suggest a general lack of knowledge regarding the effects of currently used progestins in hormonal contraception regarding these cellular and molecular brain parameters. Human neuroimaging studies were reviewed with a focus on randomized placebo-controlled trials and cross-sectional studies controlling for progestin type. The prefrontal cortex, amygdala, salience network and hippocampus were identified as regions of interest for future preclinical studies. This review proposes a series of experiments to elucidate the cellular and molecular actions of contraceptive progestins in these areas and link these actions to behavioral markers of emotional and cognitive functioning. Emotional effects of contraceptive progestins appear to be related to 1) alterations in the serotonergic system, 2) direct/indirect modulations of inhibitory GABA-ergic signalling via effects on the allopregnanolone content of the brain, which differ between androgenic and anti-androgenic progestins. Cognitive effects of combined oral contraceptives appear to depend on the ethinylestradiol dose.

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.

Pharmacokinetics of oral levonorgestrel and ethinylestradiol in women after Roux-en-Y gastric bypass surgery

BACKGROUND

Most patients undergoing Roux-en-Y gastric bypass (RYGB) are women in reproductive age. It is not known if bariatric surgery affects the pharmacokinetics of oral contraceptives.

OBJECTIVES

The primary objective was to evaluate ethinylestradiol (EE) and levonorgestrel (LNG) absorption in women undergoing RYGB, compared with nonoperated controls matched by age and body mass index (BMI). A secondary objective was to assess whether the time since surgery and BMI in the postoperative period influenced the absorption parameters.

SETTING

University hospital, Brazil.

METHODS

This study was designed to compare the maximum plasma concentration (Cmax), the time to the peak plasma level (Tmax), the area under the curve (AUC0-8 and AUC0-∞) after a single dose of a combined oral contraceptive with 0.03 mg EE and 0.15 mg LNG among 20 women after RYGB and 20 controls. Blood samples were obtained for 8 hours.

RESULTS

The mean LNG AUC0-8 and LNG AUC0-∞ were higher in RYGB group (P = .048 and P = .004, respectively). We found a positive correlation for LNG AUC0-8 (P = .045) and AUC0-∞ (P = .004) and the time since surgery, and we found a negative correlation for LNG Cmax (P = .018), AUC0-8 (P = .003), and AUC0-∞ (P = .001) and BMI.

CONCLUSION

No significant differences were found in oral EE pharmacokinetics. The operated group showed higher mean LNG AUC0-8 and AUC0-∞ but it was not considered clinically significant. The present study suggests that RYGB may not affect EE and LNG absorption.

Bone metabolic marker concentrations across the menstrual cycle and phases of combined oral contraceptive use

There is a need to further understand the impact of the menstrual cycle and phase of combined oral contraceptive (COC) use on the pre-analytical variability of markers of bone metabolism in order to improve standardisation procedures for clinical practice and research. The aim of this study was to assess bone metabolism marker concentrations across the menstrual cycle and phases of COC use. Carboxy-terminal cross-linking telopeptide of type I collagen (β-CTX), procollagen type 1 N propeptide (P1NP) and Bone alkaline phosphatase (Bone ALP) concentrations were assessed in eumenorrheic women (n = 14) during the early follicular, ovulatory and mid-luteal phases of the menstrual cycle and in COC (Microgynon®) (n = 14) users on day 2-3 of pill consumption (PC1), day 15-16 pill consumption (PC2) and day 3-4 of the pill free interval (PFI). β-CTX was significantly (-16%) lower at PC2 compared to PC1 (P = 0.015) in COC users and was not affected by menstrual cycle phase (P > 0.05). P1NP and Bone ALP were not significantly different across either menstrual cycle phase or phase of COC use (all P > 0.05). There was no difference in pooled bone marker concentrations between eumenorrheic women and COC users (P > 0.05). In contrast to some previous studies, this study showed that bone marker concentrations do not significantly fluctuate across the menstrual cycle. Furthermore, bone resorption markers are significantly affected by phase of COC use, although bone formation markers do not significantly vary by COC phase. Therefore, the phase of COC use should be considered in clinical practice and research when assessing markers of bone metabolism as this can impact circulating concentrations of bone metabolic markers yet is not currently considered in existing guidelines for best practice.

Quantitative Assessment of Levonorgestrel Binding Partner Interplay and Drug-Drug Interactions Using Physiologically Based Pharmacokinetic Modeling

Levonorgestrel (LNG) is the active moiety in many hormonal contraceptive formulations. It is typically coformulated with ethinyl estradiol (EE) to decrease intermenstrual bleeding. Due to its widespread use and CYP3A4‐mediated metabolism, there is concern regarding drug‐drug interactions (DDIs), particularly a suboptimal LNG exposure when co‐administered with CYP3A4 inducers, potentially leading to unintended pregnancies. The goal of this analysis was to determine the impact of DDIs on the systemic exposure of LNG. To this end, we developed and verified a physiologically‐based pharmacokinetic (PBPK) model for LNG in PK‐Sim (version 8.0) accounting for the impact of EE and body mass index (BMI) on LNG’s binding to sex‐hormone binding globulin. Model parameters were optimized following intravenous and oral administration of 0.09 mg LNG. The combined LNG‐EE PBPK model was verified regarding CYP3A4‐mediated interaction by comparing to published clinical DDI study data with carbamazepine, rifampicin, and efavirenz (CYP3A4 inducers). Once verified, the model was applied to predict systemic LNG exposure in normal BMI and obese women (BMI ≥ 30 kg/m²) with and without co‐administration of itraconazole (competitive CYP3A4 inhibitor) and clarithromycin (mechanism‐based CYP3A4 inhibitor). Total and free LNG exposures, when co‐administered with EE, decreased 2‐fold in the presence of rifampin, whereas they increased 1.5‐fold in the presence of itraconazole. Although changes in total and unbound exposure were decreased in obese women compared with normal BMI women, the relative impact of DDIs on LNG exposure was similar between both groups.

Pharmacokinetics of Oral Levonorgestrel in Women After Roux-en-Y Gastric Bypass Surgery and in BMI-Matched Controls

BACKGROUND

Women are advised to primarily use non-oral contraceptive alternatives after Roux-en-Y gastric bypass since it is not known if the surgery affects the pharmacokinetics of oral contraceptives.

METHODS

This is a multi-center, open label, phase 2 pharmacokinetic study performed at the University Hospital of Linköping and the Clinical Trials Center, Department of Obstetrics and Gynecology, Danderyd Hospital, Karolinska Institutet, Stockholm, Sweden. Fifteen women aged 18-40 years who had previously undergone Roux-en-Y gastric bypass surgery and reached a BMI < 30 were included. Fifteen BMI-matched women with no previous history of Roux-en-Y gastric bypass surgery served as a control group. After administration of a single dose of a combined oral contraceptive containing 0.03 mg ethinylestradiol/0.15 mg levonorgestrel, serum levonorgestrel concentrations were determined during a 24-h period using ultra performance liquid chromatography/tandem mass spectrometry. The area under the plasma concentration time curve of levonorgestrel (AUC0-24h) was the main outcome measure.

RESULTS

There were no significant differences in the studied pharmacokinetic parameters, AUC0-24h, total AUC, peak serum concentration (Cmax), time to peak serum concentrations (Tmax), apparent oral clearances of levonorgestrel (CLoral), or terminal half-lives (t½) between the groups.

CONCLUSION

This is to our knowledge the first study to evaluate the pharmacokinetics of oral levonorgestrel in women with a BMI < 30 at least 1 year after RYGB compared with a BMI-matched group of women. We could not find any significant pharmacokinetic differences between the groups, suggesting that oral levonorgestrel may be used in non-obese women after Roux-en-Y gastric bypass once a stable body weight has been reached.

CLINICAL TRIAL NUMBER

EudraCT 2014-004677-17.

Hormone Therapy and Breast Cancer: Emerging Steroid Receptor Mechanisms

Although hormone therapy is widely used by millions of women to relieve symptoms of menopause, it has been associated with several side-effects such as coronary heart disease, stroke and increased invasive breast cancer risk. These side-effects have caused many women to seek alternatives to conventional hormone therapy, including the controversial custom-compounded bioidentical hormone therapy suggested to not increase breast cancer risk. Historically estrogens and the estrogen receptor were considered the principal factors promoting breast cancer development and progression, however, a role for other members of the steroid receptor family in breast cancer pathogenesis is now evident, with emerging studies revealing an interplay between some steroid receptors. In this review, we discuss examples of hormone therapy used for the relief of menopausal symptoms, highlighting the distinction between conventional hormone therapy and custom-compounded bioidentical hormone therapy. Moreover, we highlight the fact that not all hormones have been evaluated for an association with increased breast cancer risk. We also summarize the current knowledge regarding the role of steroid receptors in mediating the carcinogenic effects of hormones used in menopausal hormone therapy, with special emphasis on the influence of the interplay or crosstalk between steroid receptors. Unraveling the intertwined nature of steroid hormone receptor signaling pathways in breast cancer biology is of utmost importance, considering that breast cancer is the most prevalent cancer among women worldwide. Moreover, understanding these mechanisms may reveal novel prevention or treatment options, and lead to the development of new hormone therapies that does not cause increased breast cancer risk.

Clarification of contraceptive drug pharmacokinetics in obesity

Related to concerns about the role of obesity in the efficacy of contraceptive drugs, a review of the literature was carried out in regard to the pharmacokinetics of ethinyl estradiol and various progestins given by various routes of administration. Most studies show that obese women exhibit modestly lower plasma concentrations of these drugs (circa 30%) when given the same doses as normal-weight women. While the mechanism is uncertain, precedence in the literature suggests that this is due to body weight-related differences in metabolism rates. Confusing in some of the literature is that a few studies have reported erroneously calculated pharmacokinetic parameters after multiple dosing of oral contraceptives. A demonstration of appropriate pharmacokinetic methodology is provided.

Perspectives on variability in pharmacokinetics of an oral contraceptive product

The early literature and reviews have described the pharmacokinetics (PK) of oral contraceptive (OC) compounds such as ethinyl estradiol (EE) and levonorgestrel (LNG) in women as subject to large intersubject variability. This was partly due to the use of diverse radioimmunoassays, limited sampling periods and an incomplete understanding of single- vs. multiple-dose kinetics and the role of EE in causing both inhibition of hepatic metabolism along with induction of sex hormone binding globulin. Over the past two decades, LNG and EE have been used as target drugs for the assessment of possible drug interactions upon introduction of many new therapeutic agents. This has resulted in at least 17 publications that describe the PK of LNG and EE in women using various 150 mcg/30 mcg products under fairly standard multiple-dose conditions. A review of these studies indicates only moderate variability in the C_max and area under the curve both within and across these studies. There is impressive similarity in these drug exposure indices found in studies carried out with several products by investigators at numerous sites and countries.

Evaluation of the Effect of Tofacitinib on the Pharmacokinetics of Oral Contraceptive Steroids in Healthy Female Volunteers

Tofacitinib is an oral Janus kinase inhibitor. Tofacitinib metabolism is primarily mediated by cytochrome P450 3A4. This phase 1 randomized, open-label, 2-way crossover study (NCT01137708) evaluated the effect of tofacitinib 30 mg twice daily on the single-dose pharmacokinetics of combination oral contraceptives ethinylestradiol (EE) and levonorgestrel (LN). EE and LN were administered as a single Microgynon 30® tablet (30 μg EE and 150 μg LN) to 19 healthy women. In the presence of tofacitinib, the area under the curve from time zero to infinity (AUC∞ ) increased by 6.6% and 0.9% for EE and LN, respectively. Maximal plasma concentrations decreased by 10.4% for EE and increased by 12.2% for LN when coadministered with tofacitinib. The 90% confidence intervals for the adjusted geometric mean ratios for AUC∞ fell within the 80%-125% region for both EE and LN. Mean half-life was similar in the presence and absence of tofacitinib: 13.8 and 13.3 hours, respectively, for EE; 25.9 and 25.4 hours, respectively, for LN. Tofacitinib had no clinically relevant net inhibitory or inductive effect on the pharmacokinetics of EE and LN. Therefore, there is no evidence to suggest dose adjustments of oral contraceptive drugs containing EE or LN when coadministered with tofacitinib.

From single chemicals to mixtures--reproductive effects of levonorgestrel and ethinylestradiol on the fathead minnow

The aquatic environment is polluted with thousands of chemicals. It is currently unclear which of these pose a significant threat to aquatic biota. The typical exposure scenario is now represented by a widespread blanket of contamination composed of myriads of individual pollutants-each typically present at a low concentration. The synthetic steroids, 17α-ethinylestradiol and levonorgestrel, have been widely reported to be present in the aquatic environment in the low ng to sub-ng/l range. They are widely used in contraceptive formulations, both individually and in combination. Our research employed the fathead minnow (Pimephales promelas) 21 day 'pair-breeding' assay to assess reproductive output when pairs of fish were exposed to the single chemicals at low environmentally relevant concentrations, and then to a binary mixture of them. A variety of endpoints were assessed, including egg production, which was inhibited in a concentration-dependent manner by both the individual chemicals and the mixture. Significant, sex specific effects were also seen with both chemicals, at differing levels of biological organisation. Plasma concentrations of EE2 and levonorgestrel were predicted and in the case of levonorgestrel measured, and compared with the human therapeutic plasma concentrations (Read-Across approach) to support the interpretation of the results. A novel quantitative method was developed for the data analysis, which ensured a suitable endpoint for the comparative mixture assessment. This approach compares the reproductive performance from individual pairs of fish during chemical exposure to its pre-treatment performance. The responses from the empirical mixture study were compared to predictions derived from the single substance data. We hypothesised combined responses which were best described by the concept of concentration addition, and found no clear indications against this additivity expectation. However, the effect profiles support the current knowledge that both compounds act in different ways to reduce egg production in fish, and suggest that probably response addition (also called Independent action) is the more appropriate mixture model in this case.

Effect of a combined estrogen and progesterone oral contraceptive on circulating adipocytokines adiponectin, resistin and DLK-1 in normal and obese female rhesus monkeys

BACKGROUND

Hormonal contraception is the most common medication used by reproductive aged women but there is little understanding of the impact of hormonal contraception on obesity and metabolism. Adipokine levels (adiponectin, resistin) and markers of adipocyte development (DLK-1) are altered in obese animals and humans and are associated with increased cardiovascular risk. We sought to determine the effect of combined hormonal oral contraceptive pills (COCs) on circulating adiponectin, resistin and DLK-1 levels in obese and normal-weight rhesus macaque monkeys.

METHODS

Serum adiponectin, resistin and DLK-1 levels in reproductive-age female rhesus macaques of normal (n = 5, mean = 5.76 kg) and inherently obese (n = 5, mean = 8.11 kg) weight were determined before, during and 2 months after cessation of 8 months of continuous treatment with COCs.

RESULTS

The obese group alone showed a significant decrease (p<.01) in weight with COC use, which returned to baseline after COC cessation. Baseline adiponectin levels prior to COC treatment were lower in the obese group (p<.05). Adiponectin levels increased from baseline in both groups, but more so in the obese group (p<.05). Resistin levels were similar at baseline, with an increase in both groups following treatment. Circulating resistin remained elevated above baseline levels after COC cessation, particularly in the obese group (p<.05). While DLK-1 levels did not change significantly in either group, a trend for higher levels in obese animals was observed.

CONCLUSIONS

COC use may alter metabolic processes via direct (resistin) or indirect (adiponectin) means, while unchanging DLK1 levels suggest they do not affect adipocyte development. COCs may directly increase resistin levels, as observed in both groups. As adiponectin is inversely related to adipocyte mass, increased levels in the obese group are likely attributed to weight loss.

Levonorgestrel intrauterine system: bleeding disorders and anticoagulant therapy

Hemostatic disorders in women are frequently associated with long-standing menorrhagia. This leads to significant morbidity and adversely affects quality of life. Management of these women poses a particular challenge; medical treatments may be contraindicated, and surgery carries additional risks. The levonorgestrel intrauterine system (LNG-IUS) has been shown to be highly efficacy in reducing menstrual blood loss in women with normal coagulation. It is also a reliable and reversible contraceptive. Data on the use of this system in women with bleeding disorders or those receiving anticoagulant therapy are limited. Analysis of data from four reported studies suggests that LNG-IUS is a viable and safe option for the management of menorrhagia in these women. Whether the underlying hemostatic disorders lead to a shorter duration of action or prolonged irregular bleeding/spotting post insertion is unknown and requires large prospective studies. Proper counselling remains crucial for patients' satisfaction.

Endothelial function across an oral contraceptive cycle in women using levonorgestrel and ethinyl estradiol

Oral contraceptive pills (OCPs) are a popular contraception method. Currently, lower-dose ethinyl estradiol formulations are most commonly prescribed, although they have been linked to increased arterial vascular risk. The aim of this study was to investigate endothelial function in healthy young women using lower-dose ethinyl estradiol OCPs. We examined flow-mediated, endothelium-dependent and nitroglycerin-mediated, endothelium-independent vasodilation of the brachial artery, comparing two doses of ethinyl estradiol/levonorgestrel OCPs in 15 healthy young women on two study days: once during the active phase and once during the placebo phase of an OCP cycle. Group low dose (LD) ( n = 7) active pills contained 150 μg levonorgestrel/30 μg ethinyl estradiol versus Group very low dose (VLD) ( n = 8) with 100 μg levonorgestrel/20 μg ethinyl estradiol. Endothelium-dependent vasodilation was lower during the active phase in Group VLD (5.33 ± 1.77% vs. 7.23 ± 2.60%; P = 0.024). This phase difference was not observed in Group LD (8.00 ± 0.970% vs. 7.61 ± 1.07%; P = 0.647). Endothelium-independent vasodilation did not differ between phases in either group. Finally, we measured endothelium-dependent vasodilation in two additional women who received 10 μg of unopposed ethinyl estradiol. Endothelium-dependent vasodilation was increased by unopposed ethinyl estradiol compared with the placebo phase (10.88 ± 2.34% vs. 6.97 ± 1.83%). These results suggest that levonorgestrel may antagonize the activity of ethinyl estradiol. Thus both the progestin type and estradiol dose need to be considered when assessing arterial vascular risk of OCP use in women.

Pregnancy in a patient with a displaced levonorgestrel-releasing intrauterine system: a case report

We report the case of a 39-year-old woman who became pregnant despite a levonorgestrel-releasing intrauterine system (LNG-IUS), which was inserted 40 months before the pregnancy was detected. When a Caesarean section was performed, the LNG-IUS was found within the omentum majus. It has been reported, that displaced LNG-IUS can cause amenorrhea and high plasma levels of LNG in affected women, probably due to the higher resorptive capacity of the peritoneum, recommending a removal of the displaced LNG-IUS. Our case report demonstrates that a dislocated LNG-IUS does not necessary has the ability to suppress ovulation and therefore pregnancy. Therefore, every gynaecologist should be aware of a pregnancy despite a dislocated LNG-IUS.

Cutaneous postural vasoconstriction is modified by exogenous but not endogenous female hormones in young women

Previously reported attenuation of skin postural vasoconstriction in women during the luteal menstrual cycle phase may be due to a progesterone-mediated decrease in myogenic or veno-arteriolar (VAR) mechanisms. Skin perfusion was measured in the shin and foot dorsum by Laser Doppler Fluxometry during leg dependency that increased vascular transmural pressure below (myogenic constriction only) and above (myogenic and VAR) the 25 mmHg threshold for activation of the VAR, and during venous distension to activate the VAR alone (cuff inflation to 50 mmHg). In six young women with normal menstrual cycles, vasoconstrictor responses to all interventions did not differ between days 7-13 (follicular) and 18-23 (luteal) of the normal menstrual cycle when progesterone levels were low and at their peak respectively. In eight women taking combined oral contraceptives (OC) and tested during pill consumption days, reductions in foot skin perfusion were smaller (P = 0.05) than in the luteal phase of the normal cycle for leg dependency below (-36.9 +/- 5.2% OC vs. -52.5 +/- 7.8% luteal, mean +/- S.E.M.) and above (-43.7 +/- 3.4% OC vs. -55.1 +/- 4.8% luteal) the VAR threshold, and for venous distension (-53.1 +/- 2.6% OC vs. 66.4 +/- 5.5% luteal). In women with normal menstrual cycles, impaired postural vasoconstriction may be confined to those who experience pre-menstrual symptoms rather than a direct effect of endogenous hormones. Reduced vasoconstriction in the dependent foot during OC use is consistent with the known vasodilator action of exogenous hormones and its long-term effects.

Impact of oral contraceptives on sex hormone-binding globulin and androgen levels: a retrospective study in women with sexual dysfunction

INTRODUCTION

Oral contraceptives (OCs) have been the preferred method of birth control because of their high rate of effectiveness. OC use, however, has been associated with women's sexual health complaints and androgen insufficiency. OC use is associated with a decrease of androgen ovarian synthesis and an increase in the production of sex hormone-binding globulin (SHBG). There have been limited studies assessing SHBG values after discontinuation of OC use.

AIM

To retrospectively investigate SHBG levels before and after discontinuation of OC use.

MAIN OUTCOME MEASURE

Sex hormone-binding globulin values were compared at baseline, while on the OC, and well beyond the 7-day half-life of SHBG at 49-120 (mean 80) days and >120 (mean 196) days after discontinuation of OCs.

METHODS

A total of 124 premenopausal women with sexual health complaints for >6 months met inclusion/exclusion criteria. Three groups of women were defined: (i) "Continued-Users" (N = 62; mean age 32 years) had been on OCs for >6 months and continued taking them; (ii) "Discontinued-Users" (N = 39; mean age 33 years) had been on OCs for >6 months and discontinued them; and (iii) "Never-Users" (N = 23; mean age 36 years) had never taken OCs.

RESULTS

Sex hormone-binding globulin values in the "Continued-Users" were four times higher than those in the "Never-User" group (mean 157 +/- 13 nmol/L vs. 41 +/- 4 nmol/L; P < 0.0001). Despite a decrease in SHBG values after discontinuation of OC use, SHBG levels in "Discontinued-Users" remained elevated in comparison with "Never-Users" (N = 26; P < 0.0001 for >120 days).

CONCLUSION

In women with sexual dysfunction, SHBG changes in "Discontinued-Users" did not decrease to values consistent with "Never-Users." Long-term sexual, metabolic, and mental health consequences might result as a consequence of chronic SHBG elevation. Does prolonged exposure to the synthetic estrogens of OCs induce gene imprinting and increased gene expression of SHBG in the liver in some women? Prospective research is needed.

Comparison of ethinylestradiol pharmacokinetics in three hormonal contraceptive formulations: the vaginal ring, the transdermal patch and an oral contraceptive

This open-label, randomized study compared the pharmacokinetics of ethinylestradiol (EE) from the contraceptive vaginal ring NuvaRing (15 microg EE/day), the transdermal patch (20 microg EE/day) and a combined oral contraceptive (COC) containing 30 microg EE. After 2-8 weeks of synchronization by COC treatment, subjects were randomized to 21 days of treatment with NuvaRing, patch or COC. Analysis of area under the EE concentration-versus-time curve (AUC) during 21 days of treatment showed that exposure to EE in the NuvaRing group was 3.4 times lower than in the patch group (p < .05) and 2.1 times lower than in the pill group (p < .05). Serum EE levels of subjects showed much lower variation with NuvaRing than with the patch or the COC. Thus, exposure to EE was significantly lower with NuvaRing than with the patch and pill methods, demonstrating that NuvaRing is a low-estrogen-dose contraceptive method that also results in low estrogen exposure.

Serum distribution of the major metabolites of norgestimate in relation to its pharmacological properties

Norelgestromin (NGMN) and levonorgestrel (LNG) are the main active metabolites of norgestimate (NGM), but their relative contributions to the pharmacological effects of NGM are unclear. We have therefore determined the serum distribution of these NGM metabolites and assessed their steady-state concentrations in women following >or=3 cycles of oral contraceptive (OC) use. The administration of 250 microg NGM/35 microg ethinyl estradiol (EE) resulted in significantly higher sex hormone-binding globulin (SHBG) levels (p = 0.002), and 30% lower serum non-protein-bound (NPB) levels of testosterone, when compared to treatment with 150 microg LNG/30 microg EE. We also confirmed that NGMN does not bind to SHBG, and found that 97.2% of this metabolite is bound to albumin while only 2.8% is in the NPB fraction. In contrast, most of the LNG was bound to SHBG (92.5% and 87.2% after NGM/EE and LNG/EE treatment, respectively), and the NPB fraction of LNG (0.7%) during NGM/EE treatment was lower (p < 0.001) than during LNG/EE treatment (1.4%). Combining these serum distributions with the C(max) and AUC(0-24h) data obtained after NGM/EE treatment gave NPB and albumin-bound values of NGMN that were much greater than the corresponding LNG values. Furthermore, the C(max) and AUC(0-24h) values for NPB LNG during NGM/EE treatment were estimated to be lower than during LNG/EE treatment. Since LNG is primarily bound by SHBG, its access to target tissues is restricted. Moreover, because SHBG does not bind NGMN, it appears to be quantitatively the more important NGM metabolite available to target tissues, and probably accounts for a substantial proportion of the progestogenic activity of NGM/EE OCs. However, it is also possible that simultaneous exposure of NGMN and LNG after treatment with NGM/EE may provide clinical benefits not seen with LNG/EE combinations.

The effect of tolterodine on the pharmacokinetics and pharmacodynamics of a combination oral contraceptive containing ethinyl estradiol and levonorgestrel

BACKGROUND

Tolterodine is an antimuscarinic agent for the treatment of overactive bladder, a chronic condition that is particularly common in women. Given the prevalence pattern of overactive bladder and the widespread use of oral contraception, circumstances are likely to arise in which physicians may wish to prescribe tolterodine for patients already taking oral contraceptives. Based on a search of MEDLINE from 1990 to 2001, there have been no studies of whether concomitant use of these agents entails a risk of drug-drug interaction or conception.

OBJECTIVE

This study investigated the effects of tolterodine on the pharmacokinetics and pharmacodynamics of a low-dose combination oral contraceptive (ethinyl estradiol 30 microg/levonorgestrel 150 microg).

METHODS

This was an open-label, randomized, 2-period crossover study in healthy women. Oral contraception was given for 21 days either alone or in combination with oral tolterodine 2 mg BID (on days 1-14) over two 28-day contraceptive cycles. Pharmacokinetic assessments were performed on day 14 based on plasma levels of ethinyl estradiol and levonorgestrel up to 24 hours after dosing and serum tolterodine levels at 1 to 3 hours after dosing. The potential for pharmacodynamic interaction was assessed in terms of the risk of failure of suppression of ovulation based on serum levels of estradiol and progesterone measured throughout each cycle.

RESULTS

Twenty-four healthy women (age, 23-41 years [mean, 30 years]; height, 155-178 cm [mean, 167 cm]; body weight, 51-75 kg [mean, 64 kg]) participated in the study. There was no evidence of a pharmacokinetic interaction between tolterodine and the steroid hormones in the oral contraceptive used, nor did the oral contraceptive show any relevant pharmacokinetic interaction with tolterodine. Serum levels of estradiol and progesterone indicated suppression of ovulation in both treatment periods.

CONCLUSION

In this selected population. coadministration of tolterodine did not affect the contraceptive efficacy of a low-dose combination oral contraceptive containing ethinyl estradiol and levonorgestrel.

A 1-year pharmacokinetic investigation of a novel oral contraceptive containing drospirenone in healthy female volunteers

Drospirenone is a novel synthetic progestogen with a pharmacological profile similar to that of natural progesterone. It has been developed in combination with ethinylestradiol for use as an oral contraceptive (EE/DRSP, Yasmin, Schering AG, Berlin, Germany). The pharmacokinetic characteristics of drospirenone and ethinylestradiol have been assessed in healthy female volunteers over a 1-year period. During each of the 13 treatment cycles, volunteers received the combined active ingredients for 21 days, followed by a 7-day, tablet-free interval. The concentrations of the serum proteins, sex hormone binding globulin (SHBG) and corticoid binding globulin (CBG), were determined at intervals after the cessation of treatment (day 21) at the end of cycles 1, 6, 9 and 13. Drospirenone and ethinylestradiol were found to be absorbed rapidly and to reach a peak concentration in serum 1.5-2.0 h after dosing. Serum concentrations ofdrospirenone declined, with mean terminal half-lives of 30.8-32.5 h. Accumulation of both drospirenone and ethinylestradiol was observed within a treatment cycle, with a mean accumulation ratio of 3.0 for drospirenone and 2.1 for ethinylestradiol. In addition, serum drospirenone concentrations increased between treatment cycles 1 and 6, but remained steady thereafter, as reflected in the AUC values determined at the end of treatment cycles 1, 6, 9 and 13. Serum SHBG and CBG concentrations declined in a biphasic manner after cessation of treatment at the end of cycle 13, and physiological steady-state concentrations were reached within 4-6 weeks. In conclusion, drospirenone was absorbed at a similar rate as other synthetic progestogens contained in various oral contraceptives, as indicated by similar tmax values. The terminal half-life of drospirenone was intermediate between those of 19-nortestosterone derivatives like desogestrel, levonorgestrel or gestodene and C21-progestogens like cyproterone acetate. Both active ingredients of the new contraceptive EE/DRSP showed accumulation within a treatment cycle, which is also the case with other synthetic progestogen/ethinylestradiol combinations. Similar to other oral contraceptives, a reversible induction of serum SHBG and CBG concentrations was observed under EE/DRSP treatment.

Increased mean platelet volume after oestrogen replacement therapy

The effect of hormone replacement therapy (HRT) on platelet size was examined in 38 post-menopausal women before and at end of a 6 week period of HRT. Subjects were treated with cyclical L-norgestrel 75 mg daily from days 17 to 28 of a 28-day cycle combined with continuous conjugated equine oestrogens 0.625 mg daily. Platelet-rich plasma was obtained to measure platelet indices by Coulter analysis. Plasma measurements of luteinizing hormone, follicle stimulating hormone and 17 beta-oestradiol were measured by immunoassays. Platelet membrane fatty acids were measured by gas-liquid chromatography. A significant reduction in platelet membrane linoleic acid, di-homo-gamma-linoleic acid and arachidonic acid of 8.1%, 14.3% and 17.8%, respectively was noted after 6 weeks of HRT (p < 0.01). There was an increase in the platelet count (not significant) and platelet volume (MPV) (P < 0.05) after 6 weeks of hormone therapy. HRT appears to increase mean platelet volume which may indicate an increase in platelet reactivity. There was no correlation between the changes in mean platelet volume and membrane fatty acid changes in platelets after such therapy.

An enzyme immunoassay for serum and urinary levonorgestrel in human and non-human primates

A microtiter plate enzyme immunoassay (EIA) is reported for the measurement of levonorgestrel (LNG) in serum and urine samples of human and non-human primates, and the results are compared to data obtained by radioimmunoassay (RIA). Rabbit polyclonal antibodies were raised against the bovine serum albumin conjugate of the 3-O-carboxymethyl oxime (CMO) derivative of LNG. The enzyme label was produced by the conjugation of horseradish peroxidase to LNG at the 3-position by the same CMO bridge used for the immunogen. The assay requires 2.5 hours to perform using 2.2-azino-di-(3-ethylbenzthiazoline sulfonic acid) diammonium salt as the chromogenic substrate. Serum (100 microliters) is extracted with petroleum ether prior to assay, whereas urine samples (25 microliters) are diluted and measured directly. The sensitivity of the assay is 0.25 pg/well with a 50% displacement of label at 7.5-9.5 pg and a linear response through 250 pg/well. Minimum levels of 8.7 and 10.0 pg/ml can be detected in serum and urine samples, respectively. Changes in serum LNG concentrations were measured in women and non-human primates following LNG implantation or injection. In the non-human primate study, serum LNG concentrations began to rise rapidly following i.m. injection of LNG, with peak levels occurring on days 3 to 5, then decreasing to approximately 25-35% of peak levels for the duration of the study. Circulating concentrations of 1.86 +/- 0.18 ng/ml LNG were reached in women the first week post-insertion of Norplant implants and decreased by 50% at 7-10 days, 75% after 14-21 days, followed by a steady decrease during the next 60-70 days to constant low levels that exhibited a high individual variation. Correlation coefficients of EIA and RIA results were 0.988 for human serum, 0.926 for human urine, and 0.972 for non-human primate serum.

Insulin-like growth factor-binding protein-1: a biochemical marker of endometrial response to progestin during hormone replacement therapy

OBJECTIVES

To compare immunohistochemical localization of insulin-like growth factor binding protein-1 (IGFBP-1) in endometrial stromal cells with endometrial morphology during three regimens of continuous combined hormone replacement therapy.

METHODS

Endometrial samples for morphological examination and immunohistochemical staining with monoclonal antibody against IGFBP-1 were obtained from 30 menopausal women before treatment and after 12 and 24 months of continuous combined hormone replacement therapy. All women received percutaneous estradiolgel releasing 1.5 mg estradiol daily. Regarding progestins, patients were divided into three groups: one group (n = 15) had a 20 micrograms/24 h levonorgestrel-releasing intrauterine device (LNG-IUD); the women in the other two groups received micronised natural progesterone either 100 mg orally (n = 7) or 100-200 mg vaginally (n = 8) daily, 25 days per calendar month.

RESULTS

Before treatment the endometrium of all women was atrophic or subatrophic and no IGFBP-1 could be detected in any of the samples which contained enough stromal cells for evaluation. After 12 and 24 months of treatment, epithelial atrophy with decidual transformation in stroma was detected in all specimens in the LNG-IUD group, and IGFBP-1 was localized in decidualized stromal cells in all samples. In the other two groups, no signs of progestin effect were detected by microscopic examination in any of the endometrial samples and IGFBP-1 staining was completely negative in all of them.

CONCLUSION

A striking difference occurred in both morphological and biochemical response in the endometrium of women treated with LNG-IUD compared with those receiving oral or vaginal micronised progesterone during continuous combined HRT. Micronised progesterone at doses used in this study turned out to be ineffective to prevent the proliferative effect of estrogen. Immunohistochemical localization of IGFBP-1 in endometrial stromal cells strongly correlated with decidual reaction in all endometrial specimens exposed to LNG-IUD, suggesting that the immunostaining of IGFBP-1 can be used as a means of assessing the strength of progestin effect in the endometrium during HRT.

A single-dose and 3-month clinical-pharmacokinetic study with a new combination oral contraceptive

The study was performed in 14 young women. The combination oral contraceptive contained 75 microgram gestodene (GSD) and 20 microgram ethinyl estradiol (EE2) per dosage unit. The volunteers received a single dose on day 21 of a treatment-free precycle (PCd21) and, after a washout period of 7 days, used the preparation in a 21 d/7 d schedule for three months. Daily drug serum level profiles were taken on PCd21 and on days 1 and 21 of treatment cycles 1 and 3. In addition, trough drug serum levels were followed every other day during treatment cycles 1 and 3. Serum levels of GSD, EE2, CBG, SHBG and testosterone (T) were determined by means of specifically developed or commercially available RIAs. Pharmacokinetic evaluation was carried out with TOPFIT and parameters were evaluated for differences with the t-test. Main target variables were Cmax, tmax and AUC for EE2, GSD and unbound GSD on day 21, cycle 3 vs. PCd21. EE2 pharmacokinetics were in agreement with a dose of 20 microgram/unit. Single-dose Cmax of 65 pg/ml and AUC of 612 pg h ml(-1) increased by 40-60% during treatment cycles as a result of accumulation EE2 induced basal SHBG (102nmol/L) and CBG (42 microgram/ml) serum levels to about 220 nmol/L and 87 microgram/ml, respectively, at the end of treatment cycles 1 and 3. Serum T levels dropped to 50% of baseline levels during treatment cycles and free T concentrations were reduced by 60-70%. GSD pharmacokinetics at the end of treatment cycles 1 and 3 were different from single-dose pharmacokinetics. Single-dose Cmax of 3.5 ng/ml and AUC 0-24 h of 22 ng h ml(-1) increased to steady-state levels of 8-8.7 ng/ml and 90-106 ng h ml(-1), respectively. The increase in GSD levels under treatment is the result of two parallel processes, i.e. accumulation and enlargement of the specific binding compartment. This was shown by protein-binding experiments, demonstrating an increase in specific (SHBG) binding from 69% to 80% and a reduction in the free fraction of GSD by 40% during treatment. The results of GSD and EE2 pharmacokinetics obtained in the present study confirm previous results with Femodene, when the reduction in the EE2 dose by 10 microgram/d is taken into account.

Influence of high doses of vitamin C on the bioavailability and the serum protein binding of levonorgestrel in women using a combination oral contraceptive

The absence of an effect of high oral doses of vitamin C on the systemic availability of ethinylestradiol in women using a levonorgestrel-containing combination oral contraceptive (0.15 mg levonorgestrel and 0.03 mg ethinylestradiol) was demonstrated in a recent study. However, it is conceivable that the oral administration of gram quantities of vitamin C could also interfere with the sulfation of levonorgestrel (LNG) metabolites during phase II biotransformation, because sulfates represent a major part of the conjugated metabolites of LNG in the serum. This possible interaction was investigated in the aforementioned study, comparing Cmax and AUC(0-12h) values of LNG on the first and 15th day of two successive treatment cycles with and without co-medication of vitamin C. In addition, the serum protein binding of LNG and the concentration of the binding proteins SHBG and CBG were compared between both treatments. Corresponding parameters obtained during treatment with the oral contraceptive alone and during co-administration of vitamin C were evaluated statistically for possible differences. No effect of vitamin C was observed for any of the parameters investigated. Thus, the repeated oral administration of gram quantities of vitamin C does not impair the sulfation of hydroxylated metabolites of LNG. There was also no observable effect on the serum protein binding of LNG and the concentrations of SHBG and CBG in the serum. The results obtained in this study population (American women) for LNG are in good agreement with those obtained from a previous study in European women, who had taken a combination oral contraceptive containing the same doses of LNG and ethinylestradiol.

Pharmacokinetics of levonorgestrel and ethinylestradiol in 14 women during three months of treatment with a tri-step combination oral contraceptive: serum protein binding of levonorgestrel and influence of treatment on free and total testosterone levels in the serum

The pharmacokinetics of levonorgestrel (LNG) and ethinylestradiol (EE2) were determined in 14 healthy women (age 18 to 27 years) during a treatment period of three months with a tri-step combination oral contraceptive (Triquilar). Prior to this treatment period, the same women received a single administration of a coated tablet containing 0.125 mg LNG together with 0.03 mg EE2. There was a washout phase of one week between both treatments. Following single dose administration, a mean terminal half-life of 22 h was observed for LNG. The total clearance was 1.0 ml x min-1 x kg-1 and the volume of distribution was 128 l. During a treatment cycle, LNG levels in the serum accumulated by a factor of about four as compared to single dose administration. Steady-state drug levels were reached during the second half of each cycle. As compared to single dose administration, the following changes were observed for LNG at the end of treatment cycles one and three: reduced total (0.5 ml x min-1 x kg-1) and free clearance (50 ml x min-1 x kg-1) and a reduced volume of distribution (52 l). A concomitant increase in the SHBG concentrations by a factor of two as compared to pretreatment values was observed during treatment and appeared to be mainly responsible for the changes in the pharmacokinetics of LNG. Marked changes were also seen for the serum protein binding of LNG. After single dose administration, the free fraction of LNG was 1.4% and the fractions bound to SHBG and albumin were 55.0% and 43.6%, respectively. At the end of cycle one, the free fraction was only 1.0% and the fractions bound to SHBG and albumin were 69.4% and 30.0%, respectively. There was no difference in corresponding pharmacokinetic parameters and in the serum protein binding of LNG at the end of cycles one and three. On the last day of treatment cycles one and three, the AUC(0-4h) values of EE2 were 331.2 and 369.6 pg x ml-1 x h, respectively, which corresponds to an about 11-24% increase as compared to single dose administration, where an AUC(0-4h) value of 298.3 pg x ml-1 x h was found. Total and free testosterone concentrations decreased during treatment cycles one and three by about 41% and 55%, respectively, compared with the corresponding values measured prior to treatment.

Influence of changes in the concentration of sex hormone-binding globulin in human serum on the protein binding of the contraceptive steroids levonorgestrel, 3-keto-desogestrel and gestodene

The serum protein binding of levonorgestrel, gestodene and 3-keto-desogestrel has been determined during several clinical studies with different oral contraceptive formulations and one in vitro study. The results of these studies were combined in order to assess the relation between changes in the concentration of sex hormone-binding globulin (SHBG) and the effect on the free fraction of the progestins as well as on their distribution with respect to the binding proteins albumin and SHBG. Although marked differences in protein binding were seen for the three progestins at low concentrations of SHBG, these differences became less pronounced at high levels of SHBG which were reached during established oral contraceptive therapy. A nonlinear relation could be shown for either the free or the protein-bound fraction of the progestins and the concentration of SHBG in the serum, respectively.