Pharmacokinetic interaction between the CYP3A4 inhibitor ketoconazole and the hormone drospirenone in combination with ethinylestradiol or estradiol

Bioequivalence study of low dose drospirenone/ethinyl estradiol 3 mg/0.03 mg film tablets under fasting conditions in Turkish healthy female subjects

This bioequivalence research aims to evaluate the relative bioavailability and pharmacokinetic characteristics of ethinyl estradiol and drospirenone in the test preparation in comparison to the reference preparation during fasting conditions. A liquid chromatography method with tandem mass spectrometry was used to determine the concentrations of drospirenone and ethinyl estradiol in plasma. The pharmacokinetic parameters that were analyzed were the maximum plasma concentration (Cmax), time to achieve Cmax (tmax), elimination half life, and area under the concentration time curve of plasma (AUC0-t, AUC0-∞ for ethinyl estradiol, and AUC0-72h for drospirenone). Both the AUC and Cmax parameters were determined to be between 80.00% and 125.00% (90% confidence intervals), which is the acceptable range. Based on the study findings, it was concluded that the test formulation, which includes 3 mg of drospirenone and 0.03 mg of ethinyl estradiol, demonstrated bioequivalence when compared to the reference formulation.

Physiologically-based pharmacokinetic modeling of prominent oral contraceptive agents and applications in drug-drug interactions

Considerable interest remains across the pharmaceutical industry and regulatory landscape in capabilities to model oral contraceptives (OCs), whether combined (COCs) with ethinyl estradiol (EE) or progestin-only pill. Acceptance of COC drug-drug interaction (DDI) assessment using physiologically-based pharmacokinetic (PBPK) is often limited to the estrogen component (EE), requiring further verification, with extrapolation from EE to progestins discouraged. There is a paucity of published progestin component PBPK models to support the regulatory DDI guidance for industry to evaluate a new chemical entity's (NCE's) DDI potential with COCs. Guidance recommends a clinical interaction study to be considered if an investigational drug is a weak or moderate inducer, or a moderate/strong inhibitor, of CYP3A4. Therefore, availability of validated OC PBPK models within one software platform, will be useful in predicting the DDI potential with NCEs earlier in the clinical development. Thus, this work was focused on developing and validating PBPK models for progestins, DNG, DRSP, LNG, and NET, within Simcyp, and assessing the DDI potential with known CYP3A4 inhibitors (e.g., ketoconazole) and inducers (e.g., rifampicin) with published clinical data. In addition, this work demonstrated confidence in the Simcyp EE model for regulatory and clinical applications by extensive verification in 70+ clinical PK and CYP3A4 interaction studies. The results provide greater capability to prospectively model clinical CYP3A4 DDI with COCs using Simcyp PBPK to interrogate the regulatory decision-tree to contextualize the potential interaction by known perpetrators and NCEs, enabling model-informed decision making, clinical study designs, and delivering potential alternative COC options for women of childbearing potential.

Ketoconazole-loading strategy to improve antifungal activity and overcome cytotoxicity on human renal proximal tubular epithelial cells

Ketoconazole (KTZ), an antifungal agent used to treat localized or systemic fungal infections by inhibiting ergosterol synthesis, exhibits restricted efficacy within eukaryotic cells owing to its elevated toxicity and limited solubility in water. This study aims to improve the biological activity and overcome cytotoxic effects in the renal system of the hydrophobic KTZ by incorporating it into poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) utilizing biomaterial nano-engineering techniques. KTZ-loaded PLGA NPs (KTZ-NPs) were prepared by single emulsion solvent evaporation method and characterized by using dynamic light scattering (DLS), electrophoretic light scattering (ELS), Fourier transform-infrared (FT-IR) spectroscopy and scanning light microscopy (SEM). Particle size and zeta potential of KTZ-NPs were determined as 182.0 ± 3.27 nm and -27.4 ± 0.56 mV, respectively. Antifungal activity was analyzed with the time-kill and top agar dilution methods onCandida albicans(C. albicans) andAspergillus flavus(A. flavus). Both KTZ and KTZ-NPs caused a significant decrease inA. flavuscell growth; however, the same effect was only observed in time-killing analysis onC. albicans, indicating a methodological difference in the antifungal analysis. According to the top agar method, the MIC value of KTZ-NPs againstA. flavuswas 9.1μg ml-1, while the minimum inhibition concentration (MIC) value of KTZ was 18.2μg ml-1. The twofold increased antifungal activity indicates that nanoparticular drug delivery systems enhance the water solubility of hydrophobic drugs. In addition, KTZ-NPs were not cytotoxic on human renal proximal tubular epithelial cells (HRPTEpCs) at fungistatic concentration, thus reducing fungal colonization without cytotoxic on renal excretion system cells.

Pharmacological and metabolic effects of drospirenone as a progestin-only pill compared to combined formulations with estrogen

The spironolactone derivative drospirenone is combined with ethinylestradiol or estetrol in combined oral contraceptives. Formulations with 17-β-estradiol are used to treat climacteric symptoms. A drospirenone-only formulation has been introduced for contraception. Here, the pharmacological properties of drospirenone, the impact of the different formulations on metabolic and laboratory parameters, and the resulting clinical implications are reviewed. Ethinylestradiol, an inhibitor of CYP metabolic enzymes, changes the pharmacokinetics of drospirenone, leading to a higher drospirenone exposure with ethinylestradiol/drospirenone compared to the drospirenone-only preparation. In addition, several metabolic alterations have been described. The impact of estetrol is less pronounced, and for 17-β-estradiol/drospirenone and drospirenone-only, decreased triglyceride and cholesterol levels were observed. Ethinylestradiol induces various pro-coagulatory factors, leading to hypercoagulability. The effect is significantly reduced with estetrol, and no influence was observed with the drospirenone-only preparation. The anti-mineralocorticoid activity of drospirenone seems to positively counteract the renin-angiotensin-aldosterone-system-activating action of ethinylestradiol. There is no influence on blood pressure with ethinylestradiol/drospirenone and estetrol/drospirenone formulations, while in clinical trials, a reduction has been observed with 17-β-estradiol/drospirenone and drospirenone-only. Anti-aldosterone activity via non-renal mineralocorticoid receptors is associated with cardiovascular health, while interactions with parathyroid hormone signaling impact bone structure and vascular calcification. Though the clinical relevance is unclear for drospirenone, data in this context are reviewed. To sum up, the advantages of drospirenone in hormonal contraception and treatment of menopausal symptoms have been demonstrated for all the formulations described here. Combination with estrogen confers benefits and risks, which must be considered.

Evaluation of the food effect on a drospirenone only contraceptive containing 4 mg administered with and without high-fat breakfast in a randomised trial

Background

The objective of the present trial was to assess the difference in pharmacokinetics (PK) of an oral test preparation containing 4 mg drospirenone (DRSP) under fasting conditions compared to PK upon food intake after single dose administration.

Methods

Open label, single centre, two-treatment, two-sequence, crossover study in 24 healthy female volunteers, with duration of 1 day per sequence and with a real wash-out period of 14 days to investigate the relative bioavailability of DRSP with both forms of administration. The 90% confidence intervals (CI) were calculated for the intra-individual ratio (test with food vs. without food) of the PK endpoints Area under the curve; 0–72 h [AUC(0-72 h₎] and maximal plasma concentration [Cmax] of DRSP.

Results

The 90% CI calculated by analysis of variance using logistic transformation (ANOVA-log) for the endpoint, intra-individual ratio (Test ‘A’ = with food intake) vs. Test ‘B’ = without food intake) of AUC(0-72 h) of drospirenone was between 104.72 and 111.36%. The 90% CI calculated by means of ANOVA- log for the endpoint intra-individual ratio (Test ‘A’ vs. Test ‘B’) of Cmax of DRSP was between 118.58 and 141.10%. The mean relative bioavailability of the test with food ‘A’ compared to the Test without food ‘B’ after single dose administration based on the endpoints AUC(0-72 h₎ was 107.99%; for the endpoint Cmax it was 129.35%.

Conclusions

The rate of absorption, based on the endpoint Cmax of DRSP was increased by about 30% under fed conditions. With respect to consumer habits, this may represent a relevant benefit for contraceptive safety, as the time span between food consumption and pill intake does not play a role.

Implications

Our results suggest that the food intake has no impact on the absorption of 4 mg DRSP in the management of contraception. This increases the contraceptive efficacy as no interference with food is expected when consuming the oral formulation under real life conditions.

Trail registration: Trial registration number: EudraCT-No: 2012–004,309-28.

A novel estetrol-containing combined oral contraceptive: European expert panel review

PURPOSE

Despite considerable advances in recently developed combined oral contraceptives (COCs), resulting in lower rates of adverse events while maintaining contraceptive efficacy, there is interest in further innovation.

MATERIALS AND METHODS

Estetrol (E4), a native oestrogen, and progestin drospirenone (DRSP) were combined in a new COC. A European expert panel reviewed the pharmacology, efficacy, and safety and tolerability of this combination. Their findings are presented as a narrative review.

RESULTS

E4 15mg/DRSP 3 mg in a 24/4 regimen provided effective contraception with good cycle control, characterised by a predictable regular bleeding pattern and minimal unscheduled bleeding, together with a good safety profile. The combination was associated with high user satisfaction, wellbeing, and minimal changes in body weight. The effects on endocrine and metabolic parameters were limited, and the combination was found to have a limited impact on liver function and lipid and carbohydrate metabolism. Moreover, its effect on several haemostatic parameters was lower than that of comparators containing ethinyl oestradiol (EE) 20mg/DRSP 3 mg and EE 30mg/levonorgestrel 150mg.

CONCLUSION

E4 15 mg/DRSP 3 mg provides safe and effective contraception, with high user satisfaction and predictable bleeding. Further research will evaluate the long-term safety of the COC.

Development of a Translational Exposure-Bracketing Approach to Streamline the Development of Hormonal Contraceptive Drug Products

Worldwide, 922 million women of reproductive age (or their partners) use some sort of contraception to prevent pregnancy. Oral combined hormonal contraceptives (CHC) typically utilize a combination of a progestin and an estrogen. CHC are potentially at risk to metabolic drug-drug interaction (DDI) via CYP3A4, the main enzyme involved in the oxidative metabolism of ethinyl estradiol (EE) and most progestins, e.g. levonorgestrel (LNG) and drospirenone (DRSP). Recently, the FDA issued a guidance addressing metabolic DDIs in the realm of CHC, establishing an overall class-based recommendation with respect to avoidance of CYP3A4 induction interactions. Given that different progestins have varying magnitudes of fraction metabolized by CYP3A4 (fm_CYP3A4 ), it would be of clinical benefit to determine if all progestins are at the same risk to CYP3A4-mediated metabolic DDI. LNG and DRSP are commonly used progestins that are at the margins of the rifampicin induction effect observed in vivo since they have the relatively lowest and highest fm_CYP3A4 among commonly used CHC formulations containing norgestimate, desogestrel, norgestrel, and norethindrone. Therefore, we applied a multi-pronged strategy, i.e. (1) development of the PBPK models, (2) comparison of the effect of CYP3A inducers and inhibitors on DRSP vs. LNG, and (3) providing the clinical-practice context based on real world data, to explore the difference in DDI risk for oral CHCs.

Leveraging Human Plasma-Derived Small Extracellular Vesicles as Liquid Biopsy to Study the Induction of Cytochrome P450 3A4 by Modafinil

Preparations of plasma-derived small extracellular vesicles (sEVs) were deployed as liquid biopsy to study cytochrome P450 (CYP) 3A4 (CYP3A4) induction following modafinil 400 mg once daily × 14 days (young healthy volunteers, N = 10 subjects). Induction was confirmed using the 4β-hydroxycholesterol-to-cholesterol (4βHC/C) ratio, a plasma CYP3A4/5 biomarker, with a mean 2.1-fold increase (Day 15 vs. Day 1; 90% confidence interval (CI) = 1.8-2.3; P value = 0.0004). Proteomic analysis revealed the induction (mean Day 15 vs. Day 1 fold-increase (90% CI)) of both liver (1.3 (1.1-1.5), P value = 0.014) and nonliver (1.9 (1.6-2.2), P value = 0.04) sEV CYP3A4 protein expression. In CYP3A5 nonexpresser subjects, the baseline (pre-dose) 4βHC/C plasma ratio was more highly correlated with liver sEVs (r = 0.937, P value = 0.001) than nonliver sEVs (r = 0.619, P value = 0.101) CYP3A4 protein expression. When CYP3A5 expressers (CYP3A5*1/*3) were included, the correlation with liver sEVs (r = 0.761, P value = 0.011) and nonliver sEVs (r = 0.391, P value = 0.264) CYP3A4 protein was weaker. Although modafinil-induced changes in plasma 4βHC/C ratio did not correlate with sEVs CYP3A4 protein expression, the individual subject sEVs proteomic data were used successfully to predict victim drug (midazolam, triazolam, dextromethorphan, 17α-ethinylestradiol, and abemaciclib) area under the plasma concentration-time curve (AUC) ratios (AUCRs) following modafinil. Based on the AUCR values, modafinil was classified as a weak to moderate CYP3A4 inducer (vs. rifampicin). For the first time, it was possible to deploy plasma-derived sEVs to study CYP3A4 induction beyond rifampicin, a more potent CYP3A4 inducer.

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.

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.

Factors Associated With Serum Estradiol Levels Among Postmenopausal Women Using Hormone Therapy

OBJECTIVE

To identify factors associated with serum estradiol (E2) levels among healthy postmenopausal women using hormone therapy (HT).

METHODS

This is an unplanned post hoc analysis of data from ELITE (Early versus Late Intervention Trial with Estradiol), a randomized controlled trial of 1 mg oral E2 with or without vaginal progesterone in healthy early compared with late (<6 years compared with 10 or more years since menopause) postmenopausal women. We included results from visits when women reported at least 80% compliance with HT. Mixed-effects linear models identified factors associated with serum E2 levels while participants were taking HT, assessed every 6 months over a median follow-up of 4.8 years and adjusted for baseline E2 level, visit, and reduced E2 dose. Possible correlates evaluated included demographics, clinical characteristics, medication use, and biomarkers of liver and kidney metabolic function.

RESULTS

The analysis included 2,160 E2 measurements in 275 postmenopausal women. Mean±SD age was 55.4±3.9 vs 64.4±5.5 years, and mean±SD time since menopause was 3.6±1.8 vs 16.0±5.6 years for early vs late postmenopausal women. Adjusted for pretreatment E2 level, visit, and reduced dose indicator, higher serum E2 levels were associated with higher body mass index (BMI), higher weight, surgical menopause, alcohol use, and antihypertensive medication use. Current and past smoking and antifungal medication use were associated with lower serum E2 levels. In the multivariable model, higher BMI and alcohol use were associated with higher serum E2 levels, whereas current and past smoking were associated with lower serum E2 levels. These factors were similar between early and late postmenopausal women.

CONCLUSION

Factors associated with serum E2 levels among postmenopausal women taking HT include BMI, alcohol use, and smoking. As serum E2 levels relate to HT effect, achievement of desirable E2 levels may be maximized through personalized intervention.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT00114517.

Confirmation of the drug-drug interaction potential between cobicistat-boosted antiretroviral regimens and hormonal contraceptives

BACKGROUND

Cobicistat (COBI), a CYP3A inhibitor, is a pharmacokinetic enhancer that increases exposures of the HIV protease inhibitors (PIs) atazanavir (ATV) and darunavir (DRV). The potential drug interaction between COBI-boosted PIs and hormonal contraceptives, which are substrates of intestinal efflux transporters and extensively metabolized by CYP enzymes, glucuronidation and sulfation, was evaluated.

METHODS

This was a Phase I, open-label, two cohort (n=18/cohort), fixed-sequence study in healthy females that evaluated the drug-drug interaction (DDI) between multiple-dose ATV+COBI or DRV+COBI and single-dose drospirenone/ethinyl estradiol (EE). DDIs were evaluated using 90% confidence intervals of the geometric least-squares mean ratios of the test (drospirenone/EE+boosted PI) versus reference (drospirenone/EE) using lack of DDI boundaries of 70-143%. Safety was assessed throughout the study.

RESULTS

29/36 participants completed the study. Relative to drospirenone/EE alone, drospirenone area under the plasma concentration versus time curve extrapolated to infinity (AUC_inf) was 1.6-fold and 2.3-fold higher, and maximum observed plasma concentration (C_max) was unaltered, upon coadministration with DRV+COBI and ATV+COBI, respectively. EE AUC_inf decreased 30% with drospirenone/EE + DRV+COBI and was unchanged with ATV+COBI + drospirenone/EE, relative to drospirenone/EE alone. Study treatments were generally well tolerated. The majority of adverse events were mild and consistent with known safety profiles of the compounds.

CONCLUSIONS

Consistent with COBI-mediated CYP3A inhibition, drospirenone exposure increased following coadministration with COBI-containing regimens, with a greater increase with ATV+COBI. Thus, clinical monitoring for drospirenone-associated hyperkalaemia is recommended with DRV+COBI and ATV+COBI should not be used with drospirenone. Lower EE exposure with DRV+COBI may be attributed to inductive effects of DRV on CYP enzymes and/or intestinal efflux transporters (that is, P-gp) involved in EE disposition.

Multicenter, phase III trials on the contraceptive efficacy, tolerability and safety of a new drospirenone-only pill

INTRODUCTION

Approximately 100 million women currently use combined oral contraceptives. Combined oral contraceptives use is associated with increased risk of venous thromboembolic events and cardiovascular disease. Progestin-only pills do not increase the risk of venous thromboembolic events, stroke and myocardial infarction but are associated with a poor cycle control. A novel estrogen-free pill containing only drospirenone (DRSP) was developed to improve bleeding pattern, tolerability and acceptance without increasing venous thromboembolic events risks in contraception.

MATERIAL AND METHODS

Two prospective, multicenter Phase III studies in healthy women aged 18-45 years were performed to demonstrate the efficacy and safety of a drospirenone-only pill in a regimen of 24 days of 4 mg of drospirenone tablets followed by 4 days of placebo. A total of 1571 women (14 329 exposure cycles) were analyzed: 713 patients in the 13-cycle study 1 with 7638 exposure cycles and 858 patients in the 9-cycle study 2 with 6691 exposure cycles. The primary endpoint was the overall Pearl index, calculated for each study separately, and for both pooled. As main secondary efficacy endpoint, the "method failure Pearl index" including all pregnancies during "perfect medication cycles" was evaluated. EudraCT registration numbers: 2010-021787-15 & 2011-002396-42.

RESULTS

Calculations on pooled studies 1 and 2 with 1571 patients gave an overall Pearl index (based on 14 329 cycles) of 0.7258 (95% CI 0.3133 to 1.4301). No single case of deep vein thrombosis or pulmonary embolism and only one case of hyperkalemia were reported. Additional information such as laboratory parameters, body mass index, bodyweight, heart rate and blood pressure showed no statistically significant changes due to the treatment.

CONCLUSIONS

This is the first report of a new drospirenone-only oral contraceptive providing clinical efficacy similar to combined oral contraceptives, with a good safety profile, and favorable cycle control.

Structural Perspectives of the CYP3A Family and Their Small Molecule Modulators in Drug Metabolism

Cytochrome P450 enzymes function to catalyze a wide range of reactions, many of which are critically important for drug response. Members of the human cytochrome P450 3A (CYP3A) family are particularly important in drug clearance, and they collectively metabolize more than half of all currently prescribed medications. The ability of these enzymes to bind a large and structurally diverse set of compounds increases the chances of their modulating or facilitating drug metabolism in unfavorable ways. Emerging evidence suggests that individual enzymes in the CYP3A family play discrete and important roles in catalysis and disease progression. Here we review the similarities and differences among CYP3A enzymes with regard to substrate recognition, metabolism, modulation by small molecules, and biological consequence, highlighting some of those with clinical significance. We also present structural perspectives to further characterize the basis of these comparisons.

Comparative pharmacokinetic estimates of drospirenone alone and in combination with ethinyl estradiol after single and repeated oral administration in healthy females

OBJECTIVE

To determine the pharmacokinetics (PK) of drospirenone (DRSP), alone versus in combination with ethinyl estradiol (EE), after single and repeated administration.

STUDY DESIGN

We conducted a single-centre, open-label, crossover, 2-treatment, 2-period, 2-sequence study in which non-micronized DRSP 4 mg or a combination of DRSP 3 mg and EE 0.02 mg were administered to healthy female subjects on day 1 to obtain a single-dose kinetic profile, and from day 4 to day 15 to obtain a repeated-dose kinetic profile. The maximum observed concentration (C_max) and area under the concentration/time curve (AUC) were determined in a model-independent way using non dose corrected data. Statistical analysis was based on a parametric method (ANOVA-log).

RESULTS

A total of 24 healthy female subjects were randomized 1:1 into the study. The mean relative, non-dose-corrected PK estimates after single-dose administration for the endpoints AUC_(0-72h), AUC_(0-24h) and C_max were 543.5 ng*h/mL, 296.1 ng*h/mL and 27.3 ng/mL for DRSP alone, and 442.0 ng*h/mL, 264.7 ng*h/mL and 37.5 ng/mL for the DRSP/EE combination; p < 0.001. The mean relative, non-dose-corrected PK estimates after repeated dose administration for the endpoints AUC_(0-72h), AUC_(0-24h) and C_max were 1066.8 ng*h/ml, 570.2 ng*h/mL and 41.0 ng/mL for DRSP alone, and 1394.5 ng*h/mL, 732.8 ng*h/mL and 61.4 ng/mL for the DRSP/EE combination; p < 0.001.

CONCLUSIONS

DRSP alone exhibits a lower accumulation ratio than together with EE. The extent of systemic exposure at steady-state is about 32% less with the new formulation (AUC_(0-24h), steady-state geometric mean ratio: 77.8%; 90% confidence interval: 74.6%-81.1%). This PK profile may be caused by EE.

IMPLICATIONS

Our results suggest that metabolic pathways of DRSP can be inhibited by EE resulting in higher DRSP plasma concentrations in DRSP/EE formulations than in a DRSP-alone formulation. The enzymes CYP3A4 and SULT1A1 may play a role. Additional drug-drug-interaction studies are needed to better understand these metabolic pathways and their future clinical implications.

Risk-Benefit Assessment of Ethinylestradiol Using a Physiologically Based Pharmacokinetic Modeling Approach

Current formulations of combined oral contraceptives (COC) containing ethinylestradiol (EE) have ≤35 μg due to increased risks of cardiovascular diseases (CVD) with higher doses of EE. Low‐dose formulations however, have resulted in increased incidences of breakthrough bleeding and contraceptive failure, particularly when coadministered with inducers of cytochrome P450 enzymes (CYP). The developed physiologically based pharmacokinetic model quantitatively predicted the effect of CYP3A4 inhibition and induction on the pharmacokinetics of EE. The predicted C_max and AUC ratios when coadministered with voriconazole, fluconazole, rifampicin, and carbamazepine were within 1.25 of the observed data. Based on published clinical data, an AUC_ss value of 1,000 pg/ml.h was selected as the threshold for breakthrough bleeding. Prospective application of the model in simulations of different doses of EE (20 μg, 35 μg, and 50 μg) identified percentages of the population at risk of breakthrough bleeding alone and with varying degrees of CYP modulation.

Pharmacokinetics of antifungal drugs: practical implications for optimized treatment of patients

Introduction

Because of the high mortality of invasive fungal infections (IFIs), appropriate exposure to antifungals appears to be crucial for therapeutic efficacy and safety.

Materials and methods

This review summarises published pharmacokinetic data on systemically administered antifungals focusing on co-morbidities, target-site penetration, and combination antifungal therapy.

Conclusions and discussion

Amphotericin B is eliminated unchanged via urine and faeces. Flucytosine and fluconazole display low protein binding and are eliminated by the kidney. Itraconazole, voriconazole, posaconazole and isavuconazole are metabolised in the liver. Azoles are substrates and inhibitors of cytochrome P450 (CYP) isoenzymes and are therefore involved in numerous drug–drug interactions. Anidulafungin is spontaneously degraded in the plasma. Caspofungin and micafungin undergo enzymatic metabolism in the liver, which is independent of CYP. Although several drug–drug interactions occur during caspofungin and micafungin treatment, echinocandins display a lower potential for drug–drug interactions. Flucytosine and azoles penetrate into most of relevant tissues. Amphotericin B accumulates in the liver and in the spleen. Its concentrations in lung and kidney are intermediate and relatively low myocardium and brain. Tissue distribution of echinocandins is similar to that of amphotericin. Combination antifungal therapy is established for cryptococcosis but controversial in other IFIs such as invasive aspergillosis and mucormycosis.

Drospirenone intake alters plasmatic steroid levels and cyp17a1 expression in gonads of juvenile sea bass

Drospirenone (DRO) is one of the most widely used progestins in contraceptive treatments and hormone replacement therapies. The pharmacokinetics and potential toxicological effects of DRO were investigated in juvenile sea bass (Dicentrarchus labrax) exposed through the diet (0.01-10 μg DRO/g) for up to 31 days. DRO was detected in the blood (4-27 ng/mL) of fish exposed to the highest concentration, with no significant bioaccumulation over time and no alteration of hepatic metabolizing enzymes, namely, CYP1A and CYP3A-catalysed activities and UDP-glucuronyltransferase (UGT). Pregnenolone (P5), progesterone (P4), 17α-hydroxyprogesterone (17P4), 17α-hydroxypregnenolone (17P5), androstenedione (AD) and testosterone (T) were determined in plasma and gene expression of cyp17a1, cyp19a1a and cyp11β analysed by qRT-PCR in gonads. The significant increase in plasmatic levels of 17P5, 17P4 and AD detected after 31 days exposure to 10 ng DRO/g together with the increased expression of cyp17a1 in females evidence the ability of DRO to alter steroid synthesis at low intake concentrations (7 ng DRO/day). However, the potential consequences of this steroid shift for female reproduction remain to be investigated.

Pharmacokinetic interaction between the CYP3A4 inhibitor ketoconazole and the hormone drospirenone in combination with ethinylestradiol or estradiol

AIMS

The present study was conducted to investigate the influence of the strong CYP3A4 inhibitor ketoconazole (KTZ) on the pharmacokinetics of drospirenone (DRSP) administered in combination with ethinylestradiol (EE) or estradiol (E2).

METHODS

This was a randomized, multicentre, open label, one way crossover, fixed sequence study with two parallel treatment arms. A group sequential design allowed terminating the study for futility after first study cohort. About 50 healthy young women were randomized 1 : 1 to 'DRSP/EE' or 'DRSP/E2'. Subjects in the 'DRSP/EE' group received DRSP 3 mg/EE 0.02 mg (YAZ®, Bayer) once daily for 21 to 28 days followed by DRSP 3 mg/EE 0.02 mg once daily plus KTZ 200 mg twice daily for 10 days. Subjects in the 'DRSP/E2' group received DRSP 3 mg/E2 1.5 mg (research combination) once daily for 21 to 28 days followed by DRSP 3 mg/E2 1.5 mg once daily plus KTZ 200 mg twice daily for 10 days.

RESULTS

Oral co-administration of DRSP/EE or DRSP/E2 and KTZ resulted in an increase in DRSP exposure (AUC(0,24 h)) in both treatment groups: DRSP/EE group: 2.68-fold DRSP increase (90% CI 2.44, 2.95); DRSP/E2 group: 2.30-fold DRSP increase (90% CI 2.08, 2.54). EE and estrone (metabolite of E2) exposures were increased ~1.4-fold whereas E2 exposure was largely unaffected by KTZ co-administration.

CONCLUSIONS

A moderate pharmacokinetic drug-drug interaction between DRSP and KTZ was demonstrated in this study. No relevant changes of medical concern were detected in the safety data collected in this study.