Physiologically based pharmacokinetic modelling prediction of the effects of dose adjustment in drug-drug interactions between levonorgestrel contraceptive implants and efavirenz-based ART

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.

A randomized trial of double vs single-dose etonogestrel implant to overcome the interaction with efavirenz-based antiretroviral therapy

BACKGROUND

Concomitant use of efavirenz-based antiretroviral therapy and a standard-dose etonogestrel contraceptive implant led to 82% lower etonogestrel exposure when compared with women who do not receive antiretroviral therapy. The clinical impact of this reduced exposure is supported by retrospective cohort evaluations that demonstrated higher rates of unintended pregnancies when contraceptive implants were combined with efavirenz. We hypothesized that placement of 2 etonogestrel implants in those taking efavirenz-based antiretroviral therapy could increase etonogestrel exposure and improve measures of contraceptive efficacy.

OBJECTIVE

This study compared the rate of ovulation and etonogestrel pharmacokinetics among women on efavirenz-based antiretroviral therapy who received 2 etonogestrel implants (136 mg; double implant group) in comparison with those who received 1 etonogestrel implant (68 mg; control group).

STUDY DESIGN

This randomized, open-label study enrolled Ugandan women with regular menstrual periods who were receiving efavirenz-based antiretroviral therapy for the treatment of HIV. Participants were randomized 1:1 to the double implant or control group, and the etonogestrel implant(s) were placed in the same arm at enrollment. All participants used a copper intrauterine device to prevent pregnancy. Ovulation was evaluated by weekly serum progesterone concentrations measured over 4 consecutive weeks at months 3 (weeks 9-12), 6 (weeks 21-24), and 12 (weeks 45-48). Progesterone concentrations >3 ng/mL were interpreted as ovulation. The ovulation rate in each group was compared using Fisher's exact tests for each month and generalized estimating equations over 48 weeks. Plasma was collected at day 3 and weeks 1, 4, 12, 24, 36, and 48 after implant placement and analyzed using a validated liquid chromatography-triple quadrupole mass spectrometry method for etonogestrel. Etonogestrel concentrations were summarized as median (interquartile range) and compared between groups by geometric mean ratio with 90% confidence intervals.

RESULTS

All participants (n=72) were cisgender Ugandan women with a median age of 31 years (interquartile range, 29-36), and 36 participants were enrolled in each study group. Two participants in the control group discontinued the trial; 1 at week 1 because of undetected pregnancy at entry and another at week 45 because of clinically significant depression. There were 47 ovulations over 104 person-months (45%) in 25 of 34 participants in the control group, and 2 ovulations over 108 person-months (2%) in 2 of 36 participants in the double implant group (month 3: 11 [31%] vs 0 [0%]; month 6: 17 [49%] vs 0 [0%]; month 12: 19 [56%] vs 2 [6%], respectively; all P<.001). The odds of ovulation were reduced by 97.7% (95% confidence interval, 90.1-99.5) in the double implant group over 48 weeks. At each time point, etonogestrel concentration was more than 2-fold higher in the double implant group than in the controls (geometric mean ratio, 2.30-2.83) with a geometric mean ratio of 2.83 (90% confidence interval, 1.89-3.35) at week 48. There were no differences in the adverse events between groups and no participant discontinued because of adverse events.

CONCLUSION

Over 48 weeks of combined use, placing 2 etonogestrel implants suppressed ovulation and increased plasma etonogestrel exposure when compared with 1 etonogestrel implant among women on efavirenz-based antiretroviral therapy. Doubling the dose of etonogestrel during efavirenz-based antiretroviral therapy could improve contraceptive effectiveness.

Effect of double-dose levonorgestrel subdermal implant in women taking efavirenz-based antiretroviral therapy: The DoubLNG pharmacokinetic study

OBJECTIVE

We evaluated the pharmacokinetics of double-dose levonorgestrel (LNG) implants to overcome the drug-drug interaction with efavirenz-based antiretroviral therapy (ART).

STUDY DESIGN

We conducted a nonrandomized, open-label, parallel-group, longitudinal pharmacokinetic study among Ugandan women ages 18-45 years. Participants with HIV on ART containing efavirenz 600 mg received 300 mg of LNG implants (Jadelle®, Bayer, New Zealand): 300LNG+ART group. We compared our outcomes with women without HIV using standard dose, 150 mg of LNG implants: 150LNG group. The implant was placed on day zero in both groups, and we quantified plasma LNG concentrations over 48 weeks post implant insertion. LNG pharmacokinetic parameters were estimated using noncompartmental techniques. Our primary outcome was the geometric mean ratio with 90% confidence intervals of LNG area under the concentration-time curve over 24 weeks (AUC_0-24w) between groups. Demographic data were described as median (interquartile range). A secondary outcome compared between-group percent of LNG concentrations ≥300 pg/mL, a minimum threshold selected a priori based on observed pregnancies in Ugandan women on standard-dose LNG implants plus efavirenz.

RESULTS

We enrolled 27 women in the 300LNG+ART group (34 [28.0 to 40.5] years and 61.0 [49.8-66.0] kg) and 19 women in the 150LNG group (33 [30.0 to 34.5] years and 64.9 [59.0 to 74.5] kg). LNG AUC_0-24w was 34% lower for 300LNG+ART versus 150LNG (geometric mean 9998 vs. 15,231 pg*week/mL, respectively [geometric mean ratio 0.66 (90% confidence intervals, 0.54 to 0.80)]). The percentage of participants with LNG concentrations ≥300 pg/mL was not statistically different between groups at week 24 (300LNG+ART: 74.1%; 150LNG: 89.5%; p = 0.27).

CONCLUSION

Double-dose LNG implant did not completely overcome the drug-drug interaction with efavirenz.

IMPLICATION

In women using ART containing efavirenz, placing two implant systems (300 mg) did not normalize LNG pharmacokinetics compared with the standard-dose implant (150 mg), and some women had evidence of ovulatory activity. Alternative ART without drug-drug interactions, such as dolutegravir, is recommended with contraceptive implants.

Model-Informed Drug Development for Anti-Infectives: State of the Art and Future

Model-informed drug development (MIDD) has a long and rich history in infectious diseases. This review describes foundational principles of translational anti-infective pharmacology, including choice of appropriate measures of exposure and pharmacodynamic (PD) measures, patient subpopulations, and drug-drug interactions. Examples are presented for state-of-the-art, empiric, mechanistic, interdisciplinary, and real-world evidence MIDD applications in the development of antibacterials (review of minimum inhibitory concentration-based models, mechanism-based pharmacokinetic/PD (PK/PD) models, PK/PD models of resistance, and immune response), antifungals, antivirals, drugs for the treatment of global health infectious diseases, and medical countermeasures. The degree of adoption of MIDD practices across the infectious diseases field is also summarized. The future application of MIDD in infectious diseases will progress along two planes; "depth" and "breadth" of MIDD methods. "MIDD depth" refers to deeper incorporation of the specific pathogen biology and intrinsic and acquired-resistance mechanisms; host factors, such as immunologic response and infection site, to enable deeper interrogation of pharmacological impact on pathogen clearance; clinical outcome and emergence of resistance from a pathogen; and patient and population perspective. In particular, improved early assessment of the emergence of resistance potential will become a greater focus in MIDD, as this is poorly mitigated by current development approaches. "MIDD breadth" refers to greater adoption of model-centered approaches to anti-infective development. Specifically, this means how various MIDD approaches and translational tools can be integrated or connected in a systematic way that supports decision making by key stakeholders (sponsors, regulators, and payers) across the entire development pathway.

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.

Pharmacogenetic interactions between antiretroviral drugs and vaginally administered hormonal contraceptives

OBJECTIVE

In AIDS Clinical Trials Group study A5316, efavirenz lowered plasma concentrations of etonogestrel and ethinyl estradiol, given as a vaginal ring, while atazanavir/ritonavir increased etonogestrel and lowered ethinyl estradiol concentrations. We characterized the pharmacogenetics of these interactions.

METHODS

In A5316, women with HIV enrolled into control (no antiretrovirals), efavirenz [600 mg daily with nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)], and atazanavir/ritonavir (300/100 mg daily with NRTIs) groups. On day 0, a vaginal ring was inserted, releasing etonogestrel/ethinyl estradiol 120/15 μg/day. Intensive plasma sampling for antiretrovirals was obtained on days 0 and 21, and single samples for etonogestrel and ethinyl estradiol on days 7, 14, and 21. Seventeen genetic polymorphisms were analyzed.

RESULTS

The 72 participants in this analysis included 25, 24 and 23 in the control, efavirenz, and atazanavir/ritonavir groups, respectively. At day 21 in the efavirenz group, CYP2B6 genotype was associated with increased plasma efavirenz exposure (P = 3.2 × 10), decreased plasma concentrations of etonogestrel (P = 1.7 × 10), and decreased ethinyl estradiol (P = 6.7 × 10). Compared to controls, efavirenz reduced median etonogestrel concentrations by at least 93% in CYP2B6 slow metabolizers versus approximately 75% in normal and intermediate metabolizers. Efavirenz reduced median ethinyl estradiol concentrations by 75% in CYP2B6 slow metabolizers versus approximately 41% in normal and intermediate metabolizers.

CONCLUSION

CYP2B6 slow metabolizer genotype worsens the pharmacokinetic interaction of efavirenz with hormonal contraceptives administered by vaginal ring. Efavirenz dose reduction in CYP2B6 slow metabolizers may reduce, but will likely not eliminate, this interaction.

Innovative Approaches for Pharmacology Studies in Pregnant and Lactating Women: A Viewpoint and Lessons from HIV

Medication use during pregnancy in the absence of pharmacokinetic and safety data is common, particularly for antiretrovirals, as pregnant women are not usually included in clinical trials leading to drug licensure. To date, data are typically generated through opportunistic pregnancy studies performed in the postmarketing setting, leading to a substantial time-lag between initial regulatory approval of a drug and availability of essential pregnancy-specific pharmacokinetic and safety data. During this period, health care providers lack key information on human placental transfer, fetal exposure, optimal maternal dosing in pregnancy, and maternal and fetal drug toxicity, including teratogenicity risk. We discuss new approaches that could facilitate the acquisition of these critical data earlier in the drug development process, aiding clinicians and patients in making informed decisions on drug selection and dosing during pregnancy. An integrated approach utilizing multiple novel methodologies (in vitro, ex vivo, in silico and in vivo) is needed to accelerate the availability of pharmacology data in pregnancy and lactation.

Effect of patient genetics on etonogestrel pharmacokinetics when combined with efavirenz or nevirapine ART

BACKGROUND

We previously demonstrated that etonogestrel concentrations were 82% lower in women using etonogestrel contraceptive implants plus efavirenz-based ART compared with women not receiving ART.

OBJECTIVES

To investigate the genetic contribution to this previously observed drug-drug interaction through studying SNPs in genes known to be involved in efavirenz, nevirapine or etonogestrel metabolism in the same group of women.

PATIENTS AND METHODS

Here, we present a secondary analysis evaluating SNPs involved in efavirenz, nevirapine and etonogestrel metabolism and associated etonogestrel pharmacokinetics among 57 women, 19 not receiving ART (control group), 19 receiving efavirenz- (600 mg daily) based ART and 19 receiving nevirapine- (200 mg twice daily) based ART. Associations between patient genotype and etonogestrel pharmacokinetic parameters were determined through univariate and multivariate linear regression. This study was registered at clinicaltrials.gov (NCT02082652).

RESULTS

Within the control group, CYP2B6 983 T>C was associated with 27% higher etonogestrel Cmax and 28% higher AUC0-24weeks. In the efavirenz group CYP2B6 516 G>T was associated with 43% lower etonogestrel Cmin and 34% lower AUC0-24weeks. For participants receiving nevirapine, NR1I2 63396 C>T was associated with 39% lower etonogestrel Cmin and 37% lower AUC0-24weeks.

CONCLUSIONS

This study demonstrates the influence of pharmacogenetics on the extent of drug-drug interactions between etonogestrel and efavirenz- or nevirapine-based ART. Efavirenz plus the etonogestrel contraceptive implant results in a detrimental drug-drug interaction irrespective of patient genetics, which is worsened in women possessing variant alleles for these CYP2B6 SNPs.

Interactions between Hormonal Contraception and Anti-Retroviral Therapy: An Updated Review

Purpose of review

Hormonal contraception provides women living with HIV the ability to control their fertility and avoid pregnancy-related morbidity. Due to shared metabolic pathways, there has been concern over drug-drug interactions between hormonal contraception and anti-retroviral therapy, which may affect the drugs' safety and efficacy. This article aims to provide an updated review of the most recent data around hormonal contraceptives and anti-retroviral therapy.

Recent findings

Prior data have suggested possible pharmacologic interactions between certain hormonal contraceptives and anti-retroviral therapy. The most significant interactions implicated include those between progestin-based contraceptive implants and efavirenz as well as between combined hormonal contraceptives and protease inhibitors. Most past studies, however, feature small sample sizes with few clinical outcomes reported.

Summary

Recent data since 2017 have largely affirmed prior studies on this topic, showing possible pharmacokinetic relationships between certain contraceptives and anti-retrovirals. Notably, while the effectiveness of progestin-based contraceptives, specifically the implant, appears reduced with efavirenz use, the overall effectiveness may remain higher than most other contraceptive methods. Larger studies are needed to provide further guidance before contraceptive-prescribing recommendations can be changed.

Utilization of Physiologically Based Pharmacokinetic Modeling in Clinical Pharmacology and Therapeutics: an Overview

The purpose of this review was to assess the advancement of applications for physiologically based pharmacokinetic (PBPK) modeling in various therapeutic areas. We conducted a PubMed search, and 166 articles published between 2012 and 2018 on FDA-approved drug products were selected for further review. Qualifying publications were summarized according to therapeutic area, medication(s) studied, pharmacokinetic model type utilized, simulator program used, and the applications of that modeling. The results showed a 13-fold increase in the number of papers published from 2012 to 2018, with the largest proportion of articles dedicated to the areas of infectious diseases, oncology, and neurology, and application extensions including prediction of drug-drug interactions due to metabolism and/or transporter-mediated effects and understanding drug kinetics in special populations. In addition, we profiled several high-impact studies whose results were used to guide package insert information and formulate dose recommendations. These results show that while utilization of PBPK modeling has drastically increased over the past several years, regulatory support, lack of easy-to-use systems for clinicians, and challenges with model validation remain major challenges for the widespread adoption of this practice in institutional and ambulatory settings. However, PBPK modeling will continue to be a useful tool in the future to assess therapeutic drug monitoring and the growing field of personalized medicine.

Pharmacokinetics of HIV therapies in pregnant patients: an update

INTRODUCTION

Mother-to-child transmission (MTCT) of HIV is thought to account for over 90% of new pediatric infections, and is associated with poor maternal and fetal outcomes. As such ensuring further reduction in MTCT is a priority in HIV treatment and prevention programs.

AREAS COVERED

This review aims to provide a comprehensive update on the pharmacokinetics of recently approved antiretroviral drugs and novel drug formulations and delivery systems. Alongside recent recommendations for dose adjustments, and an overview of the implications of co-infections on the pharmacokinetics of antiretrovirals relevant to pregnant HIV positive patients. Additionally, potential opportunities to progress pharmacokinetic research of new treatments in this population are highlighted.

EXPERT OPINION

In order to improve our understanding of how to provide safe and effective treatment to HIV positive pregnant women, further work is required to enable their inclusion in early stages of clinical trials. Incentives must be created for this research, in the form of additional investment by key stakeholders and regulatory agencies. Furthermore, as the incidence of MTCT is reduced globally there is a need to conduct long-term pharmacovigilance studies in uninfected children exposed to HIV and antiretrovirals in utero, in order to determine the safest and most effective antiretroviral therapies.

Predicting Drug-Drug Interactions Between Rifampicin and Long-Acting Cabotegravir and Rilpivirine Using Physiologically Based Pharmacokinetic Modeling

BACKGROUND

Cabotegravir and rilpivirine are 2 long-acting (LA) antiretrovirals that can be administered intramuscularly; their interaction with rifampicin, a first-line antituberculosis agent, has not been investigated. The aim of this study was to simulate and predict drug-drug interactions (DDIs) between these LA antiretroviral agents and rifampicin using physiologically based pharmacokinetic (PBPK) modeling.

METHODS

The designed PBPK models were qualified (according to European Medicines Agency guidelines) against observed data for oral formulations of cabotegravir, rilpivirine, and rifampicin. Induction potential of rifampicin was also qualified by comparing the DDI between oral cabotegravir and oral rilpivirine with rifampicin. Qualified PBPK models were utilized for pharmacokinetic prediction of DDIs.

RESULTS

PBPK models predicted a reduction in both area under the curve (AUC0-28 days) and trough concentration (Ctrough, 28th day) of LA cabotegravir of 41%-46% for the first maintenance dose coadministered with 600 mg once-daily oral rifampicin. Rilpivirine concentrations were predicted to decrease by 82% for both AUC0-28 days and Ctrough, 28th day following the first maintenance dose when coadministered with rifampicin.

CONCLUSIONS

The developed PBPK models predicted the theoretical effect of rifampicin on cabotegravir and rilpivirine LA intramuscular formulations. According to these simulations, it is likely that coadministration of rifampicin with these LA formulations will result in subtherapeutic concentrations of both drugs.

The need for contraception in patients taking prescription drugs: a review of FDA warning labels, duration of effects, and mechanisms of action

Introduction: This review provides a guide for the rational use of prescription drugs in patients of reproductive age. Areas covered: A comprehensive retrieval of the labels of FDA-approved drugs was performed to identify drugs where the label recommends contraceptive use during and/or after treatment. The acquired data were analyzed and organized into a table. Contraception was recommended or mandated for 268 single-ingredient drugs. These could be divided into four main categories, with many having effects across several categories: 177 drugs required contraception because they were associated with pregnancy loss or stillbirth, 177 drugs were associated with teratogenesis, 136 were associated with non-teratogenic adverse peri- or postnatal effects on the fetus (e.g. low birth weight), and 44 were associated with decreased efficacy of contraception or a change in ovulatory cycle. We also discuss the period of time contraception is required, as well as the known or hypothesized reasons for the reproductive toxicity of these agents. Expert opinion: We have provided a comprehensive overview of the FDA-approved drugs where the warning labels currently stipulate that contraception should be used. Although other references are available for clinicians, this review provides a useful source of information regarding the single-ingredient prescription drugs that may affect the outcome of pregnancy. This information is particularly relevant for researchers, as it provides an overview of the different drugs with reproductive toxicity, and because it highlights the specific needs for future research. In particular, more work (especially epidemiological studies) is needed to clarify the clinical relevance of these findings, most of which were obtained through animal studies.