Structure-based design and synthesis of novel highly potent and selective KRASG12C inhibitors.

Administering drugs via inhalational routes is an attractive approach for treating respiratory diseases. Effective lung delivery provides a rapid therapeutic effect, minimizes systemic toxicities, and enhances overall public health responses, particularly for orally inhaled products during pandemics. However, assessing the pharmacokinetic (PK) properties of inhaled agents within the airway is challenging. In silico modeling, especially using physiologically based pharmacokinetic (PBPK) models, has emerged as a crucial clinical translational tool that integrates in vitro, in vivo, and ex vivo lung model data to improve predictions of lung exposure for inhaled drugs. Developing effective PBPK models requires a deeper understanding of the factors influencing drug disposition. Membrane transporters can significantly impact airway PKs, but there is a knowledge gap regarding their role and expression within the human airways. This review explores the following: (1) preclinical and clinical studies on lung transporter localization, expression, and their potential impact on the PKs of inhaled drugs; (2) conflicting data on transporter expression and localization; and (3) factors influencing transporter expression, such as inflammatory processes and diseases. We summarize the transporters involved in inhaled drug disposition, drug-specific parameters, and current PBPK models and approaches that account for transporter involvement. Only a few studies quantify transporter protein levels in the lung, particularly for respiratory diseases, limiting the ability to incorporate lung expression levels to inform the development of enhanced PBPK models. Overall, a comprehensive understanding of lung transporters and their impact on drug disposition is crucial for estimating and optimizing model-informed dosing of inhaled therapeutics. SIGNIFICANCE STATEMENT: Inhaled drugs are ideal for treating respiratory diseases because they increase drug exposure in the lungs and minimize off-target effects. Speeding up their approval, development, and dosing relies on accurate computational models. This review examines improving these models by integrating knowledge about lung transporters, focusing on understanding, characterizing, and quantifying these transporters and their influence on drug disposition.

Physiologically based pharmacokinetic modeling of oseltamivir in pregnant rhesus macaques to inform clinical dosing across trimesters.

There is growing demand for improved in vitro liver models to better predict in vivo pharmacology, specifically drug disposition mediated by hepatic transporters and assessment of transporter-mediated drug interaction risk. While 2D sandwich-cultured human hepatocytes (SCHH) remain valuable, they are limited to short-term use due to hepatocyte de-differentiation and absence of non-parenchymal cells. Multicellular hepatic spheroids (MHS) offer a promising alternative, but transporter concentrations, functionality, and suitability for hepatobiliary transport studies remain unclear. We evaluated an all-human MHS model, comprised of transporter-certified™ cryopreserved primary human hepatocytes (PHH), Kupffer, stellate, and endothelial cells, for long-term hepatic transporter assessment. Over a 21-day culture period, we monitored transporter concentrations (targeted proteomics), regulation (RNA-seq), localization (immunofluorescence), bile acid profiles (LC-MS/MS), and functional transport (B-CLEAR®). This is the first report of protein concentrations of 13 transporters in MHS over 21days directly compared to freshly thawed PHH and SCHH from the same donor. Most transporters declined in MHS compared to PHH, while SCHH maintained or increased transporter concentrations by day 5. However, multidrug resistance-associated protein (MRP) 4 and organic solute transporter (OST)-α/β were upregulated in MHS, likely reflecting adaptation to bile acid accumulation. Bile acid profiling confirmed functional synthesis, metabolism and excretion. Functional MRP2 efflux into sealed canalicular compartments was demonstrated with the MRP2 substrate, 5(6)-carboxy-2',7'-dichlorofluorescein (CDF). Tight junction disruption of canaliculi with Ca2⁺-free buffer resulted in CDF release from canalicular compartments, with partial entrapment within MHS, likely due to the 3D architecture. These findings highlight key strengths and limitations of MHS as a model for assessing hepatobiliary transport.

The Blood-Brain Barrier (BBB) is a selective barrier that regulates the entry of molecules including nutrients, environmental toxins, and therapeutic medications into the brain. Its function continues to evolve postnatally, through aging, and disease states. Here we present a global proteomics analysis focused on the ontogeny and aging of proteins in human brain microvessels (BMVs), predominantly composed of brain endothelial cells. Our proteomic study quantified 6,223 proteins and revealed possible age-related alterations in BBB permeability due to basement membrane component changes through the early developmental stage and age-dependent changes in transporter expression. Age dependent expression changes were observed within nutrient transporters and transporters that play critical roles in drug disposition. This research 1) provides important information on the mechanisms that drive changes in the metabolic content of the brain with age and 2) enables the creation of physiologically based pharmacokinetic models for CNS drug distribution across different life stages.

The gut microbiota has emerged as a key modulator of drug metabolism, efficacy, and toxicity, adding a critical layer of complexity to pharmacological processes traditionally attributed solely to host physiology. In hepatobiliary disease, this interaction acquires particular relevance due to alterations in bile acid metabolism, intestinal barrier function, immune regulation, and enterohepatic circulation. This review synthesizes current evidence on microbiota–drug interactions within hepatobiliary contexts, integrating mechanistic, translational, and clinical data to provide a coherent pharmacological framework. The analyzed literature consistently demonstrates that intestinal microorganisms can directly biotransform xenobiotics, modify effective bioavailability, and generate metabolites with altered pharmacodynamic or toxicological properties. In parallel, microbial modulation of bile acid pools and signaling pathways indirectly influences hepatic drug-metabolizing enzymes, transporters, and inflammatory responses. The reciprocal capacity of drugs to reshape microbial composition further contributes to dynamic and time-dependent variability in drug exposure. Collectively, these mechanisms help explain interindividual differences in therapeutic response and susceptibility to adverse drug reactions that are frequently observed in hepatobiliary disease but remain insufficiently accounted for by conventional dosing paradigms. By consolidating these findings, this review highlights the gut microbiota as an integral component of hepatobiliary pharmacology and underscores its relevance for advancing more precise, individualized, and safer therapeutic strategies.

Modeling and simulations are indispensable tools to describe pharmacokinetics (PK) and pharmacodynamics to support monoclonal antibody (mAb) development. The linear PK of mAbs is commonly described by a 2-compartment PK model, while the nonlinear PK often observed at low doses is described by target mediated drug disposition (TMDD) models. Since target binding is the primary pharmacology of mAbs and receptor occupancy (RO) could impact PK through TMDD, it is desirable to have a simple mechanistic model to simultaneously describe both PK, including TMDD, and RO at the site of action (SoA). In this tutorial, we introduce a physiologically inspired PKRO (piPKRO) model for mAbs targeting membrane receptors. The linear PK part (referred to as the piPK model) is modified from the classical 2-compartment PK model to include using the physiological compartment volumes, adding drug clearance in extravascular compartments, describing mAb concentration in tissues reflecting measured partition coefficients, and target expression and drug binding based on the location of target expression. A few macroparameters including Pdist (partition coefficient) and tdist (distribution half-time) are introduced to provide an intuitive understanding of the mAb distribution. Case studies of applying the model to real world data are provided. Analysis with the piPKRO model suggests that local drug depletion could occur due to significant target mediated drug clearance at the SoA in combination with relatively slow drug distribution. This local drug depletion can lead to much lower RO at the SoA compared to RO in the central compartment and subsequently impact efficacious dose predictions.

Target-mediated drug disposition (TMDD) refers to non-linear pharmacokinetic (PK) profiles arising from the saturable interaction between a drug and its pharmacological target. Recently, our group revisited the TMDD cases observed in small-molecule drugs interacting with high-specificity targets, obtaining quantitative insights into in vivo target binding. In this study, we developed a physiologically-based PK (PBPK) model incorporating TMDD and pharmacodynamic (PD) responses (TMDD-PD) for finasteride and dutasteride, two time-dependent inhibitors of 5α-reductase (5αR). In addition to the tissue- and subtype-dependent 5αR inhibition, the model incorporated irreversible inactivation of 5αR and its turnover to account for the mechanism of time-dependent inhibition. We simultaneously analyzed the non-linear PK and PD (dihydrotestosterone level decline and recovery) data for both finasteride and dutasteride. Our model effectively captured the observed PK/PD profiles of both drugs, and the model-derived 5αR inhibition parameters were comparable to those obtained from in vitro 5αR inhibition data. Sensitivity analysis revealed that saturation of target binding is the primary driver of the non-linear PK and corresponding PD profiles, while slow turnover of 5αR contributes to the prolonged PD effect. Our results further suggest that the distinct PD profiles of finasteride and dutasteride are attributable to their differing inhibition characteristics against 5αR subtypes (selectivity and affinity). These findings extend our previous work and further support the utility of TMDD-PD modeling for optimizing clinical dose and improving therapeutic outcomes for small-molecule drugs exhibiting TMDD with time-dependent target inhibition.

Pharmacokinetics and postoperative analgesic efficacy of intravenous acetaminophen in dogs undergoing laparoscopic ovariohysterectomy.

Mechanistic insights into P-glycoprotein-driven transport of anti-cancer PARP inhibitors.

Population pharmacokinetics of imipenem in solid tumor patients with infections: A real-world study.

Intrathecal (IT) drug delivery represents a direct route to the central nervous system by bypassing the blood-brain barrier, yet optimal drug distribution and predictable pharmacokinetics (PK) remain a challenge in clinical practice. Understanding the factors impacting the CNS entry or lymphatic clearance of different therapeutic modalities may help improve CNS therapies. Using tool molecules and multi-modal imaging techniques, including MRI, dual-isotope SPECT/CT, cryo-fluorescence tomography, immunohistochemistry, we investigated key in vivo determinants of IT drug disposition and distribution patterns for small molecules, oligonucleotides and nanoparticles. Studies focused on examining the impact of CSF dynamics, parenchymal influx pathways, lymphatic clearance routes and therapeutic agent molecular properties on regional CNS exposure. Our findings demonstrate that IT drug distribution is governed by multiple interacting factors. Higher dosing volume correlate with rostral spread while reducing local sequestration. Molecular characteristics, particularly tissue binding affinity and size influence both parenchymal penetration and lymphatic clearance. Meningeal clearance to peripheral lymph nodes is prominent for large molecules and nanoparticles. Neuroaxial retention patterns of large molecules and nanoparticles reveals a CNS reticuloendothelial system that may play a role in elimination of certain therapeutic modalities. Understanding the complex interplay between dosing parameters, parenchymal influx and IT clearance routes, drug molecular properties, and patient-specific factors may help optimize delivery to CNS regions of interest. These insights are particularly relevant given the growing interest in IT administration for treating neurological disorders, especially in conditions with altered fluid dynamics and clearance pathways such as Alzheimer's disease.

Mapping the ABC transporter landscape in the human lung: A comprehensive characterisation of P-gp, MRP1 and BCRP expression and functional activity in human lung epithelial cells.

Dermal disposition characterization and development of a retrospective level A in vitro-in vivo relationship for topical metronidazole products.

Quantitative prediction of CYP2C9-mediated drug disposition using humanized mice.

ABSTRACTPer‐ and polyfluoroalkyl substances (PFAS) represent a large class of > 11,000 synthetic organofluorine compounds that are globally distributed and consistently detected in human serum. Recent studies suggest that environmentally relevant exposures to short‐chain PFAS can disrupt ATP‐binding cassette (ABC) transporters, which regulate xenobiotic disposition and are critical for human health. This study examined the effects of short‐term (45 min) and long‐term (48 h) exposures to 1 nM or 1 µM of four short‐chain PFAS, perfluorobutanesulfonic acid (PFBS), perfluorohexanoic acid (PFHxA), perfluorohexanesulfonic acid (PFHxS), and 6:2 fluorotelomer alcohol (6:2 FTOH), using differentiated HepaRG hepatocytes. Functional assays evaluated changes in efflux activity, while gene expression analysis quantified transcriptional responses across 38 ABC transporters. Following 48‐h exposures, both 1 nM and 1 µM treatments significantly decreased the retention of fluorescent substrates CMFDA, BODIPY‐cholesterol, Hoechst 33342, and Rhodamine 123 relative to controls, indicating enhanced efflux transporter activity. Consistent with these results, transcriptional analysis revealed significant upregulation of multiple ABC genes, including ABCG2 (BCRP), ABCB1 (P‐gp/MDR1), and ABCC1 (MRP1). In contrast, short‐term exposures produced no measurable effects on efflux activity. Together, these findings demonstrate that environmentally relevant concentrations of short‐chain PFAS can alter the expression and activity of key hepatic ABC transporters. Such changes may disrupt the handling of endogenous compounds and pharmaceuticals, raising concerns that low‐level PFAS exposure could influence drug disposition and human health outcomes.

Understanding the pharmacokinetics of therapeutic antibodies often requires a detailed investigation of the mechanisms governing their distribution and clearance. Two of the most important mechanisms are the salvage and recycling of antibodies by the neonatal Fc receptor (FcRn), and target-mediated drug disposition (TMDD). While the two mechanisms have been analysed individually in detail, their combination and coupling is yet to be addressed. An important point of consideration is the characteristic time scales pertaining to the processes in each mechanism and how they can be related and thus integrated into a single framework. To this end a minimal 'physiology-based' pharmacokinetic model incorporating specific (TMDD) and non-specific (FcRn) antibody elimination is investigated in the high binding-affinity limit using the method of matched asymptotic expansions. The theory builds on previous asymptotic frameworks corresponding to each mechanism individually. The combined FcRn-TMDD model consists of a plasma space and an endosomal space, with target binding occurring in the former and antibody salvage in the latter. Two parameter regimes are studied in particular, that correspond to cases wherein both the specific and the non-specific clearance mechanisms provide comparable contributions to the total antibody clearance over the same time scale. The analysis offers insight into the processes dominating antibody pharmacokinetics during each characteristic phase of the problem. In addition to the accurate analytical description of the kinetics, relevant pharmacometric expressions are also derived, such as the approximate time and concentration when the target receptors are no longer 'fully' saturated, AUC and the terminal slope. The resulting insight on the dominant processes and model parameters in the specific characteristic phases may be utilised to guide parameter estimation in future modelling efforts. Additionally, the presented theory can be used to assess the validity of various quasi-equilibrium, quasi-steady and Michaelis-Menten type assumptions in each phase. In short, the presented theory can provide guidance for physiology-based pharmacokinetic as well as standard pharmacokinetic modelling efforts.

P-glycoprotein (P-gp) greatly impacts substrate drug disposition, so much so that regulatory agencies recommend ascertaining the P-gp status of active pharmaceutical ingredients (APIs) intended for human use. Arguably, the P-gp status of drugs intended for canine patients is equally, if not more, important. Our research objectives were to assess whether human P-gp substrate data can predict canine P-gp substrate status and to explore the three previously reported binding sites within the P-gp binding pocket, the H-, R-, and P-sites. Competitive efflux assays employing cell lines expressing canine or human P-gp were used to compare the degree of overlap or independence of the three binding sites in canine versus human P-gp using site-specific fluorescent P-gp substrates rhodamine 123, calcein AM and Hoechst 33342. Because calcein AM can also be transported by multidrug resistance protein 1 (MRP1), experiments were performed to assess its potential influence on calcein AM efflux studies. Results indicate that: (i) MRP1 is either a non-factor or negligible factor for cells expressing canine or human P-gp respectively; (ii) determining an API's P-gp binding site may provide clinically relevant information; and (iii) use of human P-gp substrate data as a proxy for canine P-gp substrate data will often prove inaccurate.

IntroductionGenerally, the pregnant women with schizophrenia have higher consumption of medicinal drugs. During pregnancy, placental ABC transporters regulate drug disposition and are involved in fetal and placental development. This study examined the expression and function of placental P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) transporters in vivo and evaluated the epigenetic impact of schizophrenia on the placenta in a rat model.MethodsThe expression of placental P-gp and BCRP was measured by RT-PCR and Western blot techniques in schizophrenia-like Wisket and control Wistar rats on gestation days 15, 18, 20, 21, and 22, while the histone acetyltransferase activity and global methylation state of the placenta were detected by colorimetric kits. Fexofenadine was administered per os (10 mg/kg) to pregnant rats and plasma concentrations of fexofenadine were determined with HPLC analysis on the 21 and 22 days of gestation.ResultsReduced placental P-gp expression was identified in late pregnancy, while the placental BCRP expression upregulation was observed before term in schizophrenia. Significantly lower fetal fexofenadine plasma concentration was measured on the 21st and 22nd days of pregnancy compared to the mother; in contrast, the fexofenadine concentration was similar in the schizophrenia-like mother and fetus. Decreased placental histone acetyltransferase activity and DNA hypermethylation were revealed before term in schizophrenia-like rats.ConclusionBased on our results, we can conclude that the expression and function of the placental efflux proteins we examined are altered in schizophrenia, and possibly as a result, altered substrate concentrations were measured in the fetuses. We hypothesize that the altered protein expression may also be a result of the disease-induced epigenetic pattern changes. This study presents novel disease-associated placental ABC transporter alterations, which highlights the dangers of using transporter substrates, especially P-gp, during pregnancy.

Pharmacokinetic failure of obinutuzumab due to massive third-space sequestration in a patient with high-burden follicular lymphoma: A rationale for therapeutic drug monitoring and dose intensification