Assessment of Aging-Related Function Variations of P-gp Transporter in Old-Elderly Chinese CHF Patients Based on Modeling and Simulation

Aging-associated intestinal dysfunction impairs 5-heptadecylresorcinol absorption: Mechanistic insights into transporter-mediated uptake, barrier integrity and inflammatory regulation

5-heptadecylresorcinol (AR-C17), a key bioactive component of whole grain (WG) wheat and rye, has been shown to exhibit anti-aging properties. However, the intestinal absorption dynamics of AR-C17 across different intestinal segments, as well as the aging-dependent differences in absorption between young and aging mice and their underlying mechanisms, remain poorly understood. In this study, we systematically evaluated AR-C17 absorption in various intestinal regions using an Ussing chamber system and elucidated potential contributing factors. Our results revealed that the jejunum and ileum served as the principal sites for AR-C17 absorption, with total absorption rates (TAR) reaching approximately 60 % in young mice. Conversely, aging mice exhibited significantly diminished AR-C17 absorption, with TAR values reduced to 20-45 % in these segments. Aging-associated alterations in key absorption parameters-including apparent permeability coefficient, transmucosal resistance, and short-circuit current-were observed during AR-C17 absorption, ultimately leading to reduced uptake in aging mice. Histopathological analysis demonstrated aging-associated structural deterioration, characterized by villus damage with irregular crypt architecture in the jejunum and villus vacuolization in the ileum. These morphological changes were accompanied by downregulated expression of Oct1 in the jejunum and Octn2 in the ileum, which collectively contributed to impaired AR-C17 absorption in aging mice. Further mechanistic investigations indicated that the differential absorption of AR-C17 between young and aging mice was closely associated with alterations in transmembrane transporters, inflammation, and tight junction. This study provided compelling evidence that aging-associated intestinal dysfunction significantly attenuated AR-C17 absorption, providing novel insights for optimizing the bioavailability of WG-derived bioactive compounds in the elderly.

Microdose Cocktail Study Reveals the Activity and Key Influencing Factors of OATP1B, P-Gp, BCRP, and CYP3A in End-Stage Renal Disease Patients

OATP1B, P-gp, BCRP, and CYP3A are the most contributing drug-metabolizing enzymes or transporters (DMETs) for commonly prescribed medication. Their activities may change in end-stage renal disease (ESRD) patients with large inter-individual variabilities (IIVs), leading to altered substrate drug exposure and ultimately elevated safety risk. However, the changing extent and indictive influencing factors are not quantified so far. Here, a microdose cocktail regimen containing five sensitive substrate drugs (pitavastatin, dabigatran etexilate, rosuvastatin, midazolam, and atorvastatin) for these DMETs was administrated to Chinese healthy volunteers and ESRD patients. Drug pharmacokinetics profiles were determined, together with physiological, pharmacogenetic, and gut microbiome signature. Population pharmacokinetic and machine learning model were established to identify key influencing factors and quantify their contribution to drug exposure change. The exposure of pitavastatin, dabigatran, rosuvastatin, and atorvastatin increased to 1.8-, 3.1-, 1.1-, and 1.3-fold, respectively, whereas midazolam exposure decreased by 72% in ESRD patients. Notably, in addition to disease state, the relative abundance of genus Veillonella and Clostridium_XIVb were firstly identified as significant influencing factors for PTV and RSV apparent clearance, respectively, suggesting their indicative role for OATP and BCRP activity evaluation. Moreover, several genera were found to strongly associate with drug clearance and reduce unexplained IIVs. Accordingly, it was estimated that OATP1B and intestine P-gp activity decreased by 35-75% and 29-44%, respectively, whereas BCRP and CYP3A4 activity may upregulate to some extent. Our study provides a quantitative and mechanistic understanding of individual DMET activity and could support precision medicine of substrate drugs in ESRD patients.

Utility of physiologically based pharmacokinetic modeling in predicting and characterizing clinical drug interactions

Physiologically based pharmacokinetic (PBPK) modeling is a mechanistic dynamic modeling approach that can be used to predict or retrospectively describe changes in drug exposure due to drug-drug interactions (DDIs). With advancements in commercially available PBPK software, PBPK DDI modeling has become a mainstream approach from early drug discovery through to late-stage drug development and is often used to support regulatory packages for new drug applications. This Minireview will briefly describe the approaches to predicting DDI using PBPK and static modeling approaches, the basic model structures and features inherent to PBPK DDI models, and key examples where PBPK DDI models have been used to describe complex DDI mechanisms. Future directions aimed at using PBPK models to characterize transporter-mediated DDI, predict DDI in special populations, and assess the DDI potential of protein therapeutics will be discussed. A summary of the 209 PBPK DDI examples published to date in 2023 will be provided. Overall, current data and trends suggest a continued role for PBPK models in the characterization and prediction of DDI for therapeutic molecules. SIGNIFICANCE STATEMENT: Physiologically based pharmacokinetic (PBPK) models have been a key tool in the characterization of various pharmacokinetic phenomena, including drug-drug interactions. This Minireview will highlight recent advancements and publications around physiologically based pharmacokinetic drug-drug interaction modeling, an important area of drug discovery and development research in light of the increasing prevalence of polypharmacology in clinical settings.

Unveiling gut microbiota's role: Bidirectional regulation of drug transport for improved safety

Drug safety is a paramount concern in the field of drug development, with researchers increasingly focusing on the bidirectional regulation of gut microbiota in this context. The gut microbiota plays a crucial role in maintaining drug safety. It can influence drug transport processes in the body through various mechanisms, thereby modulating their efficacy and toxicity. The main mechanisms include: (1) The gut microbiota directly interacts with drugs, altering their chemical structure to reduce toxicity and enhance efficacy, thereby impacting drug transport mechanisms, drugs can also change the structure and abundance of gut bacteria; (2) bidirectional regulation of intestinal barrier permeability by gut microbiota, promoting the absorption of nontoxic drugs and inhibiting the absorption of toxic components; (3) bidirectional regulation of the expression and activity of transport proteins by gut microbiota, selectively promoting the absorption of effective components or inhibiting the absorption of toxic components. This bidirectional regulatory role enables the gut microbiota to play a key role in maintaining drug balance in the body and reducing adverse reactions. Understanding these regulatory mechanisms sheds light on novel approaches to minimize toxic side effects, enhance drug efficacy, and ultimately improve drug safety. This review systematically examines the bidirectional regulation of gut microbiota in drug transportation from the aforementioned aspects, emphasizing their significance in ensuring drug safety. Furthermore, it offers a prospective outlook from the standpoint of enhancing therapeutic efficacy and reducing drug toxicity, underscoring the importance of further exploration in this research domain. It aims to provide more effective strategies for drug development and treatment.

Population Pharmacokinetics and Dosing Regimen Analysis of Nirmatrelvir in Chinese Patients with COVID-19 Infection

Purpose

Nirmatrelvir/ritonavir (N/R) is the first drug to receive emergency authorization for the treatment of COVID-19 infection. We aimed to develop a population pharmacokinetic (PopPK) model to evaluate the effects of potential covariates and explore dosing regimen.

Patients and Methods

Sparse data of serum concentrations of N/R were obtained from 129 patients with COVID-19 infection receiving oral 300/100 mg N/R twice daily for 5 days. Plasma samples were assayed using ultra-high-performance liquid chromatography-tandem mass spectrometry. The PopPK model was developed using a nonlinear mixed effects approach utilizing the NONMEM 7.4 software. Monte Carlo simulation was conducted to optimize the dosage regimen.

Results

A one-compartment model with first-order absorption and first-order elimination provided the best fit for the data. Allometric scaling of parameters on creatinine clearance (CrCl) and body weight were identified as covariates that significantly influenced exposure-efficacy after oral administration of nirmatrelvir. Monte Carlo simulation using the final model generated concentration-time profiles for virtual patients (1,000 per group) with varying renal functions and body weight. Furthermore, we developed a web-based dashboard to visualize the dynamic changes in nirmatrelvir concentration and provide individualized dosage regimens.

Conclusion

This study showed that dosing regimen optimization of nirmatrelvir should be based on CrCl and body weight. Moreover, a web-based dashboard has been developed to facilitate individualized pharmacotherapy.

Model-informed drug development in pediatric, pregnancy and geriatric drug development: States of the art and future

The challenges of drug development in pediatric, pregnant and geriatric populations are a worldwide concern shared by regulatory authorities, pharmaceutical companies, and healthcare professionals. Model-informed drug development (MIDD) can integrate and quantify real-world data of physiology, pharmacology, and disease processes by using modeling and simulation techniques to facilitate decision-making in drug development. In this article, we reviewed current MIDD policy updates, reflected on the integrity of physiological data used for MIDD and the effects of physiological changes on the drug PK, as well as summarized current MIDD strategies and applications, so as to present the state of the art of MIDD in pediatric, pregnant and geriatric populations. Some considerations are put forth for the future improvements of MIDD including refining regulatory considerations, improving the integrity of physiological data, applying the emerging technologies, and exploring the application of MIDD in new therapies like gene therapies for special populations.

Mechanisms and Clinical Implications of Human Gut Microbiota-Drug Interactions in the Precision Medicine Era

The human gut microbiota, comprising trillions of microorganisms residing in the gastrointestinal tract, has emerged as a pivotal player in modulating various aspects of human health and disease. Recent research has shed light on the intricate relationship between the gut microbiota and pharmaceuticals, uncovering profound implications for drug metabolism, efficacy, and safety. This review depicted the landscape of molecular mechanisms and clinical implications of dynamic human gut Microbiota-Drug Interactions (MDI), with an emphasis on the impact of MDI on drug responses and individual variations. This review also discussed the therapeutic potential of modulating the gut microbiota or harnessing its metabolic capabilities to optimize clinical treatments and advance personalized medicine, as well as the challenges and future directions in this emerging field.

Connections between cross-tissue and intra-tissue biomarkers of aging biology in older adults

Background

Saliva measures are generally more accessible than blood, especially in vulnerable populations. However, connections between aging biology biomarkers in different body tissues remain unknown.

Methods

The present study included individuals (N = 2406) who consented for saliva and blood draw in the Health and Retirement Telomere length study in 2008 and the Venous blood study in 2016 who had complete data for both tissues. We assessed biological aging based on telomere length in saliva and DNA methylation and physiology measures in blood. DNA methylation clocks combine information from CpGs to produce the aging measures representative of epigenetic aging in humans. We analyzed DNA methylation clocks proposed by Horvath (353 CpG sites), Hannum (71 CpG sites), Levine or PhenoAge, (513 CpG sites), GrimAge, (epigenetic surrogate markers for select plasma proteins), Horvath skin and blood (391 CpG sites), Lin (99 CpG sites), Weidner (3 CpG sites), and VidalBralo (8 CpG sites). Physiology measures (referred to as phenotypic age) included albumin, creatinine, glucose, [log] C-reactive protein, lymphocyte percent, mean cell volume, red blood cell distribution width, alkaline phosphatase, and white blood cell count. The phenotypic age algorithm is based on parametrization of Gompertz proportional hazard models. Average telomere length was assayed using quantitative PCR (qPCR) by comparing the telomere sequence copy number in each patient's sample (T) to a single-copy gene copy number (S). The resulting T/S ratio was proportional to telomere length, mean. Within individual, relationships between aging biology measures in blood and saliva and variations according to sex were assessed.

Results

Saliva-based telomere length showed inverse associations with both physiology-based and DNA methylation-based aging biology biomarkers in blood. Longer saliva-based telomere length was associated with 1 to 4 years slower biological aging based on blood-based biomarkers with the highest magnitude being Weidner (β = - 3.97, P = 0.005), GrimAge (β = - 3.33, P < 0.001), and Lin (β = - 3.45, P = 0.008) biomarkers of DNA methylation.

Conclusions

There are strong connections between aging biology biomarkers in saliva and blood in older adults. Changes in telomere length vary with changes in DNA methylation and physiology biomarkers of aging biology. We observed variations in the relationship between each body system represented by physiology biomarkers and biological aging, particularly at the DNA methylation level. These observations provide novel opportunities for integration of both blood-based and saliva-based biomarkers in clinical care of vulnerable and clinically difficult to reach populations where either or both tissues would be accessible for clinical monitoring purposes.

Population pharmacokinetic modeling and simulation for nirmatrelvir exposure assessment in Chinese older patients with COVID-19 infection

Nirmatrelvir is an effective component of Paxlovid, the first oral antiviral drug granted emergency use authorization by the FDA. Nirmatrelvir is prescribed extensively in older adult patients to treat the coronavirus disease 2019 (COVID-19) infection. In this study, population pharmacokinetic modeling with clinical study data was employed to explore the pharmacokinetic profile of nirmatrelvir in older adult Chinese patients with COVID-19 infection. The result suggests that the pharmacokinetic profile of nirmatrelvir can be described by a one-compartment model with first-order absorption and elimination in this study population. The calculated apparent clearance (CL/F), apparent volumes of distribution (V/F), and absorption rate constant (ka) for the typical patient were 4.16 L/h, 39.1 L, and 0.776, respectively. The area under the curve (AUC) of nirmatrelvir in the typical Chinese older adult was approximately three-fold higher than the AUCs in Chinese and Western young adult volunteers. At the same doses, the simulated AUCs were increased by 26%, 43%, 72%, and 135% in virtual populations with creatinine clearances of 60, 45, 30, and 15 mL/min, respectively. Our research provides an instructive reference for nirmatrelvir dose selection in older Chinese adults.

Physiologically based pharmacokinetic (PBPK) modelling of oral drug absorption in older adults - an AGePOP review

The older population consisting of persons aged 65 years or older is the fastest-growing population group and also the major consumer of pharmaceutical products. Due to the heterogenous ageing process, this age group shows high interindividual variability in the dose-exposure-response relationship and, thus, a prediction of drug safety and efficacy is challenging. Although physiologically based pharmacokinetic (PBPK) modelling is a well-established tool to inform and confirm drug dosing strategies during drug development for special population groups, age-related changes in absorption are poorly accounted for in current PBPK models. The purpose of this review is to summarise the current state-of-knowledge in terms of physiological changes with increasing age that can influence the oral absorption of dosage forms. The capacity of common PBPK platforms to incorporate these changes and describe the older population is also discussed, as well as the implications of extrinsic factors such as drug-drug interactions associated with polypharmacy on the model development process. The future potential of this field will rely on addressing the gaps identified in this article, which can subsequently supplement in-vitro and in-vivo data for more robust decision-making on the adequacy of the formulation for use in older adults and inform pharmacotherapy.

Physiologically-based pharmacokinetic modeling to predict drug-drug interactions of dabigatran etexilate and rivaroxaban in the Chinese older adults

INTRODUCTION

Drug-drug interaction (DDI) is one of the major concerns for the clinical use of NOACs in the older adults considering that coexistence of multiple diseases and comorbidity were common. Current guidelines on the DDI management were established based on clinical studies conducted in healthy adults and mainly focus on the Caucasians, whereas systemic and ethnic differences may lead to distinct management in the Chinese older adults.

OBJECTIVES

To investigate the impact of aging on the DDI magnitude between P-gp and/or CYP3A4 inhibitors with dabigatran etexilate and rivaroxaban in older adults, providing additional information for the use in clinical practice.

RESULTS

Compared with the simulated adult, the AUC of the simulated older adults increased by 42-88% (DABE) and 21-60% (rivaroxaban), respectively, during NOACs monotherapy. Simulation on DDIs predicted that verapamil and clarithromycin further increase the exposure of dabigatran by 29-72% and 40-47%, whereas clarithromycin, fluconazole, and ketoconazole increase the exposure of rivaroxaban by 21-30%, 16-24%, and 194-247% in the older adults. Overall, our simulation result demonstrated that aging and DDIs both increased the exposure of NOACs. However, aging does not have a drastic impact on the extent of DDIs. The DDI ratios of young and old older adults were similar to the adults and were also similar between Caucasians and Chinese.

DISCUSSION

We further simulated the interactions under steady-state based on the EHRA guideline (2021). Our simulation results revealed that recommended reduced dosing regimen of dabigatran etexilate during comedication with verapamil and clarithromycin (110 and 75 mg BID for Chinese young and old older adults) will result in exposure (trough concentration) that was either slightly higher or similar to the trough concentration of patients with any bleeding events. Routine monitoring of bleeding risk is encouraged. Further studies on the use of rivaroxaban in Chinese older adults are warranted.

CONCLUSION

Aging and DDI increases exposure of drug in Chinese older adults. However, aging does not have a drastic impact on the extent of DDIs. Clinical management of DDIs in Chinese older adults in the absence of complex polypharmacy can a priori be similar to the EHRA guideline but routine monitoring of bleeding risk is encouraged when dabigatran etexilate given with verapamil and clarithromycin.