Effects of a protein-rich drink or a standard meal on the pharmacokinetics of elvitegravir, cobicistat, emtricitabine and tenofovir in healthy Japanese male subjects: a randomized, three-way crossover study

Social, economic, and physical side effects impact PrEP uptake and persistence among transgender women in Peru

INTRODUCTION

Oral pre-exposure prophylaxis (PrEP) for HIV-1 infection is over 99% effective in protecting against HIV acquisition when used consistently and appropriately. However, PrEP uptake and persistent use remains suboptimal, with a substantial gap in utilization among key populations who could most benefit from PrEP. In Latin America specifically, there is poor understanding of barriers to PrEP uptake and persistence among transgender (trans) women.

METHODS

In April-May 2018, we conducted qualitative interviews lasting 25-45 min as part of an end-of-project evaluation of TransPrEP, a pilot RCT that examined the impact of a social network-based peer support intervention on PrEP adherence among trans women in Lima, Peru. Participants in the qualitative evaluation, all adult trans women, included individuals who either (1) screened eligible to participate in the TransPrEP pilot, but opted not to enroll (n = 8), (2) enrolled, but later withdrew (n = 6), (3) were still actively enrolled at the time of interview and/or successfully completed the study (n = 16), or (4) were study staff (n = 4). Interviews were audio recorded and transcribed verbatim. Codebook development followed an immersion/crystallization approach, and coding was completed using Dedoose.

RESULTS

Evaluation participants had a mean age of 28.2 years (range 19-47). When describing experiences taking PrEP, participant narratives highlighted side effects that spanned three domains: physical side effects, such as prolonged symptoms of gastrointestinal distress or somnolence; economic challenges, including lost income due to inability to work; and social concerns, including interpersonal conflicts due to HIV-related stigma. Participants described PrEP use within a broader context of social and economic marginalization, with a focus on daily survival, and how PrEP side effects negatively contributed to these stressors. Persistence was, in some cases, supported through the intervention's educational workshops.

CONCLUSION

This research highlights the ways that physical, economic, and social side effects of PrEP can impact acceptability and persistence among trans women in Peru, amplifying and layering onto existing stressors including economic precarity. Understanding the unique experiences of trans women taking PrEP is crucial to informing tailored interventions to improve uptake and persistence.

Achieving big with small: quantitative clinical pharmacology tools for drug development in pediatric rare diseases

Pediatric populations represent a major fraction of rare diseases and compound the intrinsic challenges of pediatric drug development and drug development for rare diseases. The intertwined complexities of pediatric and rare disease populations impose unique challenges to clinical pharmacologists and require integration of novel clinical pharmacology and quantitative tools to overcome multiple hurdles during the discovery and development of new therapies. Drug development strategies for pediatric rare diseases continue to evolve to meet the inherent challenges and produce new medicines. Advances in quantitative clinical pharmacology research have been a key component in advancing pediatric rare disease research to accelerate drug development and inform regulatory decisions. This article will discuss the evolution of the regulatory landscape in pediatric rare diseases, the challenges encountered during the design of rare disease drug development programs and will highlight the use of innovative tools and potential solutions for future development programs.

Chemometrics as a valuable tool for evaluating interactions between antiretroviral drugs and food

AIMS

Clinically significant interactions with food occur for more than half of antiretroviral drugs. Different physiochemical properties deriving from the chemical structures of antiretroviral drugs may contribute to the variable food effect. Chemometric methods allow analysing a large number of interrelated variables concomitantly and visualizing correlations between them. We used a chemometric approach to determine the types of correlations among different features of antiretroviral drugs and food that may influence interactions.

METHODS

Thirty-three antiretroviral drugs were analysed: ten nucleoside reverse transcriptase inhibitors, six non-nucleoside reverse transcriptase inhibitors, five integrase strand transfer inhibitors, ten protease inhibitors, one fusion inhibitor and one HIV maturation inhibitor. Input data for the analysis were collected from already published clinical studies, chemical records and calculations. We constructed a hierarchical partial least squares (PLS) model with three response parameters: postprandial change of time to reach maximum drug concentration (ΔTmax ), albumin binding (%) and logarithm of partition coefficient (logP). Predictor parameters were the first two principal components of principal component analysis (PCA) models for six groups of molecular descriptors.

RESULTS

PCA models explained 64.4% to 83.4% of the variance of the original parameters (average: 76.9%), whereas the PLS model had four significant components and explained 86.2% and 71.4% of the variance in the sets of predictor and response parameters, respectively. We observed 58 significant correlations between ΔTmax , albumin binding (%), logP and constitutional, topological, hydrogen bonding and charge-based molecular descriptors.

CONCLUSIONS

Chemometrics is a useful and valuable tool for analysing interactions between antiretroviral drugs and food.

A Combination of Novel HIV-1 Protease Inhibitor and Cytochrome P450 (CYP) Enzyme Inhibitor to Explore the Future Prospective of Antiviral Agents: Evotaz

Viruses belong to the class of micro-organisms that are well known for causing infections in the human body. Antiviral medications are given out to prevent the spread of disease-causing viruses. When the viruses are actively reproducing, these agents have their greatest impact. It is particularly challenging to develop virus-specific medications since viruses share the majority of the metabolic functions of the host cell. In the continuous search for better antiviral agents, the United States Food and Drug Administration (USFDA) approved a new drug named Evotaz on January 29, 2015 for the treatment of human immunodeficiency virus (HIV). Evotaz is a combined once-daily fixed drug, containing Atazanavir, an HIV protease inhibitor, and cobicistat, an inhibitor of the human liver cytochrome P450 (CYP) enzyme. The medication is created such that it can kill viruses by concurrently inhibiting protease and CYP enzymes. The medicine is still being studied for a number of criteria, but its usefulness in children under the age of 12 is currently unknown. The preclinical and clinical characteristics of Evotaz, as well as its safety and efficacy profiles and a comparison of the novel drug with antiviral medications presently available in the market, are the main topics of this review paper.

Interactions of Antiretroviral Drugs with Food, Beverages, Dietary Supplements, and Alcohol: A Systematic Review and Meta-analyses

Multiple factors may affect combined antiretroviral therapy (cART). We investigated the impact of food, beverages, dietary supplements, and alcohol on the pharmacokinetic and pharmacodynamic parameters of 33 antiretroviral drugs. Systematic review in adherence to PRISMA guidelines was performed, with 109 reports of 120 studies included. For each drug, meta-analyses or qualitative analyses were conducted. We have found clinically significant interactions with food for more than half of antiretroviral agents. The following drugs should be taken with or immediately after the meal: tenofovir disoproxil, etravirine, rilpivirine, dolutegravir, elvitegravir, atazanavir, darunavir, lopinavir, nelfinavir, ritonavir, saquinavir. Didanosine, zalcitabine, zidovudine, efavirenz, amprenavir, fosamprenavir, and indinavir should be taken on an empty stomach for maximum patient benefit. Antiretroviral agents not mentioned above can be administered regardless of food. There is insufficient evidence available to make recommendations about consuming juice or alcohol with antiretroviral drugs. Resolving drug-food interactions may contribute to maximized cART effectiveness and safety.

Comparative Clinical Pharmacokinetics and Pharmacodynamics of HIV-1 Integrase Strand Transfer Inhibitors: An Updated Review

Bictegravir, cabotegravir, dolutegravir, elvitegravir, and raltegravir are members of the latest class of antiretrovirals available to treat human immunodeficiency virus (HIV) infection, the integrase strand transfer inhibitors. Integrase strand transfer inhibitors are potent inhibitors of the HIV integrase enzyme with IC_90/95 values in the low nanogram per milliliter range and they retain antiviral activity against strains of HIV with acquired resistance to other classes of antiretrovirals. Each of the integrase strand transfer inhibitors have unique pharmacokinetic/pharmacodynamic properties, influencing their role in clinical use in specific subsets of patients. Cabotegravir, approved for use in Canada but not yet by the US Food and Drug Administration, is formulated in both oral and intramuscular formulations; the latter of which has shown efficacy as a long-acting extended-release formulation. Cabotegravir, raltegravir, and dolutegravir have minimal drug-drug interaction profiles, as their metabolism has minimal cytochrome P450 involvement. Conversely, elvitegravir metabolism occurs primarily via cytochrome P450 3A4 and requires pharmacokinetic boosting to achieve systemic exposures amenable to once-daily dosing. Bictegravir metabolism has similar contributions from both cytochrome P450 3A4 and uridine 5'-diphospho-glucuronosyltransferase 1A1. Bictegravir, dolutegravir, and raltegravir are recommended components of initial regimens for most people with HIV in the US adult and adolescent HIV treatment guidelines. This review summarizes and compares the pharmacokinetics and pharmacodynamics of the integrase strand transfer inhibitor agents, and describes specific pharmacokinetic considerations for persons with hepatic impairment, renal dysfunction, pregnancy, and co-infections.

Impact of Therapeutic Drug Monitoring of Antiretroviral Drugs in Routine Clinical Management of People Living With HIV: A Narrative Review

BACKGROUND

The treatment of HIV infection has evolved significantly since the advent of highly active antiretroviral therapy. As a result, a response rate of 90%-95% now represents a realistically achievable target. Given this background, it is difficult to imagine the additional benefits that therapeutic drug monitoring (TDM) could provide in the management of HIV infection.

METHODS

This article is not intended to provide a systematic literature review on TDM of antiretroviral agents; rather, the authors aim to discuss the potential added value of TDM in the optimal management of people living with HIV (PLWH) in selected real-life clinical scenarios based on data collected over 10 years by their TDM service.

RESULTS

Some clinical situations, in which the selection of the optimal antiretroviral therapy is challenging, have been identified. These include poorly compliant patients, suboptimal antiretroviral therapies (in terms of both efficacy and toxicity), polypharmacy with a high risk of drug-drug interactions, and different patient populations, such as pregnant women.

CONCLUSIONS

The transformation of HIV infection from a near-universally fatal illness to a lifelong chronic disease has resulted in an HIV population that is growing and aging, placing new and increasing demands on public programs and health services. Increasingly, the management of comorbidities, polypharmacy, and drug-drug interaction, and their impact on antiretroviral therapy will have to be undertaken. These clinical settings represent some of the new frontiers for the use of TDM with the goal of achieving optimal prescription and outcome for PLWH.

Physiologically Based Pharmacokinetic Models to Predict Maternal Pharmacokinetics and Fetal Exposure to Emtricitabine and Acyclovir

Pregnancy is associated with physiological changes that may impact drug pharmacokinetics (PK). The goals of this study were to build maternal-fetal physiologically based pharmacokinetic (PBPK) models for acyclovir and emtricitabine, 2 anti(retro)viral drugs with active renal net secretion, and to (1) evaluate the predicted maternal PK at different stages of pregnancy; (2) predict the changes in PK target parameters following the current dosing regimen of these drugs throughout pregnancy; (3) evaluate the predicted concentrations of these drugs in the umbilical vein at delivery; (4) compare the model performance for predicting maternal PK of emtricitabine in the third trimester with that of previously published PBPK models; and (5) compare different previously published approaches for estimating the placental permeability of these 2 drugs. Results showed that the pregnancy PBPK model for acyclovir predicted all maternal concentrations within a 2-fold error range, whereas the model for emtricitabine predicted 79% of the maternal concentrations values within that range. Extrapolation of these models to earlier stages of pregnancy indicated that the change in the median PK target parameters remained well above the target threshold. Concentrations of acyclovir and emtricitabine in the umbilical vein were overall adequately predicted. The comparison of different emtricitabine PBPK models suggested an overall similar predictive performance in the third trimester, but the comparison of different approaches for estimating placental drug permeability revealed large differences. These models can enhance the understanding of the PK behavior of renally excreted drugs, which may ultimately inform pharmacotherapeutic decision making in pregnant women and their fetuses.

Steady-state pharmacokinetics of tenofovir disoproxil fumarate in human immunodeficiency virus-infected Chinese patients

BACKGROUND

The pharmacokinetic (PK) profile of tenofovir disoproxil fumarate in Chinese adults infected with HIV is unknown.

METHODS

A pilot, prospective, open-label study was performed to investigate the steady-state PK profile of tenofovir disoproxil fumarate in 15 Chinese HIV-infected patients among whom eight patients were treated with 300 mg tenofovir disoproxil fumarate, 300 mg lamivudine and 400/100 mg lopinavir/ritonavir, and seven with 300 mg tenofovir disoproxil fumarate, 300 mg lamivudine and 400 mg nevirapine. The plasma concentrations of tenofovir over the 24-h dosing interval were determined by HPLC. The PK parameters were calculated using the non-compartmental model in WinNonlin software.

RESULTS

The PK parameters of tenofovir in the 15 patients were determined as follows (mean ± SD): AUC_{(0-24 h)}, 4074.7 ± 1551.9 ng•h/mL; C_max,ss, 447.1 ± 217.4 ng/mL; C_trough,ss, 98.7 ± 36.7 ng/mL; t_max,ss, 1.3 ± 0.4 h; plasma t_1/2, 21.8 ± 7.6 h; and CL_ss/F, 45.8 ± 13.0 L/h.

CONCLUSION

Tenofovir demonstrated slower elimination rate and increased plasma concentration in Chinese patients compared to previously published data from Caucasian or African subjects, which may be associated with the higher incidences of renal and bone resorption dysfunction observed in our patient population. Clinicians should be cautious of the differing PK characteristics of tenofovir among people of different races.

Comparative Clinical Pharmacokinetics and Pharmacodynamics of HIV-1 Integrase Strand Transfer Inhibitors

Dolutegravir (DTG), elvitegravir (EVG) and raltegravir (RAL) are members of the latest class of antiretrovirals (ARVs) that have become available to treat human immunodeficiency virus (HIV) infection: integrase strand transfer inhibitors (INSTIs). INSTIs are potent inhibitors of the HIV integrase enzyme, with protein binding-adjusted concentration inhibiting viral replication by 90/95 % [IC90/95] values in the low nanogram per millilitre range, and they retain antiviral activity against strains of HIV with acquired resistance to other classes of ARVs. Each of the INSTIs has unique pharmacokinetic/pharmacodynamic properties, influencing its role in clinical use in specific subsets of patients. RAL and DTG have minimal drug-drug interaction profiles, as their metabolism has minimal cytochrome P450 (CYP) involvement. Conversely, EVG metabolism occurs primarily via CYP3A4 and requires pharmacokinetic boosting to achieve systemic exposures amenable to once-daily dosing. EVG and DTG have the added benefit of availability of fixed-dose combination tablets, allowing for convenient and simplified ARV regimens. RAL is the only INSTI to be listed as a preferred agent in the current US perinatal treatment guidelines. All three INSTIs are recommended regimens for treatment-naïve individuals in the US adult and adolescent HIV treatment guidelines. This review summarizes and compares the pharmacokinetics and pharmacodynamics of the INSTIs, and describes specific pharmacokinetic considerations for special patient conditions: hepatic impairment, renal dysfunction, pregnancy and co-infections.

Elvitegravir for the treatment of HIV

INTRODUCTION

Current antiretrovirals (ARVs) have demonstrated the ability to prolong the life of an HIV infected individual via suppression of the virus and subsequent restoration of immune function. Despite significant advancement, there remains an opportunity for improvement. One ARV that attempts to fill global HIV therapeutic needs by balancing convenience, safety, and efficacy is elvitegravir (EVG). Areas covered: Using MEDLINE/PubMed, a literature search was conducted for published articles on the safety and efficacy of EVG in the treatment of HIV infection. Expert opinion: EVG offers clinicians a convenient choice for HIV-positive patients that is safe and effective for both treatment-naïve and experienced patients, as well as an option for regimen simplification in virologically suppressed patients. EVG is conveniently co-formulated in fixed dose combination tablets to be taken once daily with food. EVG does not require dose adjustment for patients with severe renal impairment or mild to moderate liver disease. Importantly, EVG requires co-administration with a pharmacokinetic enhancer (i.e., ritonavir or cobicistat) in order to achieve therapeutic levels and facilitate once daily dosing. As a consequence, clinicians must carefully review concomitant medications and navigate potential drug-drug interactions mediated through potent inhibition of cytochrome P450 3A enzymes by ritonavir and cobicistat.

When food can make the difference: The case of elvitegravir-based co-formulation

Stribild should be administered under fed conditions to optimize drugs exposure. Here we assessed to what extent this advice is applied in the real life scenario by therapeutic drug monitoring in 75 HIV-infected patients given Stribild-based antiretroviral therapy. Fifty-three percent of our patients took Stribild at lunch/supper time, 23% in the morning with breakfast, and 24% middle in the morning or late in the evening. Twelve out of the 75 patients had unquantifiable elvitegravir concentrations, whereas in the remaining the levels were largely distributed. Wide inter-individual variability in the tenofovir, cobicistat and darunavir trough concentrations was also observed. In real life settings a significant proportion of patients took Stribild without food, namely in the mid-morning or late in the evening. This resulted in a wide inter-individual variability of antiretroviral drug trough concentrations. To avoid the risk for patients to experience suboptimal drug exposure, it is important that health professionals more convincingly advise their patients to take Stribild in fed conditions. On the other hand, the role of patient education and patient responsibility to correctly take the therapy should not be underestimated.

Clinical use of cobicistat as a pharmacoenhancer of human immunodeficiency virus therapy

The pharmacoenhancement of plasma concentrations of protease inhibitors by coadministration of so-called boosters has been an integral part of antiretroviral therapy for human immunodeficiency virus (HIV) for 1.5 decades. Nearly all HIV protease inhibitors are combined with low-dose ritonavir or cobicistat, which are able to effectively inhibit the cytochrome-mediated metabolism of HIV protease inhibitors in the liver and thus enhance the plasma concentration and prolong the dosing interval of the antiretrovirally active combination partners. Therapies created in this way are clinically effective regimens, being convenient for patients and showing a high genetic barrier to viral resistance. In addition to ritonavir, which has been in use since 1996, cobicistat, a new pharmacoenhancer, has been approved and is widely used now. The outstanding property of cobicistat is its cytochrome P450 3A-selective inhibition of hepatic metabolism of antiretroviral drugs, in contrast with ritonavir, which not only inhibits but also induces a number of cytochrome P450 enzymes, UDP-glucuronosyltransferase, P-glycoprotein, and other cellular transporters. This article reviews the current literature, and compares the pharmacokinetics, pharmacodynamics, and safety of both pharmacoenhancers and discusses the clinical utility of cobicistat in up-to-date and future HIV therapy.

Cobicistat: Review of a Pharmacokinetic Enhancer for HIV Infection

PURPOSE

This article reviews the clinical pharmacology, pharmacodynamic and pharmacokinetic (PK) properties, clinical efficacy and tolerability, drug interactions, and dosing and administration of cobicistat.

METHODS

Searches of MEDLINE and International Pharmaceutical Abstracts from 1964 to February 2015 were conducted using the search terms cobicistat and GS-9350. Relevant information was extracted from the identified clinical trials and review articles. Abstracts from the Conference on Retroviruses and Opportunistic Infections (2014-2015) and the Interscience Conference on Antimicrobial Agents and Chemotherapy (2013-2014) were also searched.

FINDINGS

Cobicistat is a PK enhancer lacking antiviral activity that, via selective cytochrome P-450 (CYP) 3A inhibition, inhibits the metabolism of certain antiretroviral medications and is used for prolonging their effect. Cobicistat has been studied as a booster of elvitegravir, a second-generation integrase inhibitor, and of the protease inhibitors atazanavir and darunavir. Data on its clinical efficacy and tolerability have been presented in 2 Phase II trials and in 9 Phase III trials, which reported durable efficacy in terms of achievement of sustained suppression of HIV-1 RNA levels to <50 copies/mL for at least 48 weeks. Cobicistat was generally well-tolerated in these studies. Cobicistat may increase serum creatinine levels via the inhibition of proximal renal tubular cell transporters and thus reduce estimated glomerular filtration rate, although it does not appear to affect actual glomerular filtration rate. Given the potent CYP3A inhibition by cobicistat, its coadministration with drugs metabolized by CYP3A may result in increased plasma concentrations of such agents. Moreover, as cobicistat is metabolized predominantly by CYP3A, plasma concentrations may increase or decrease on coadministration with CYP3A inhibitors or inducers, respectively.

IMPLICATIONS

With potent durability through 48 weeks, a tolerability profile comparable to other first- and second-line antiretroviral therapies, and a convenient dosing schedule with low daily pill burden in fixed-dose combination tablets, cobicistat is a potential addition to the management of HIV infection as a PK enhancer. However, the effects of cobicistat on serum creatinine and its considerable drug-interaction potential may warrant additional monitoring.