Wooin Lee

Propranolol is a widely-used β-adrenergic blocker with extensive pharmacokinetic (PK) data across multiple species, rendering it appropriate for comparing various interspecies scaling methodologies. The present study aimed to apply a quantitative interspecies PK modeling framework for propranolol using literature-derived datasets from seven mammalian species, namely, mouse, rat, rabbit, cat, dog, human, and horse. Conventional allometric analyses indicated body weight-dependent relationships for both clearance and steady-state volume of distribution. For the top-down minimal physiologically-based pharmacokinetic (mPBPK) modeling approach, the model incorporated two peripheral tissue compartments governed by shared distribution parameters across different species. The simultaneous fitting of intravenous (IV) propranolol PK data from seven species to the mPBPK model produced parameter estimates that reasonably captured the observed plasma PK data. Subsequent individual fitting of IV and oral propranolol PK data for each species adequately estimated additional absorption-related parameters. To improve physiological interpretability, top-down parameter estimates were aligned with bottom-up whole-body PBPK parameters via tissue-lumping principles. A unitless product-ratio plot further provided species-dependent kinetic distinctions on the biological half-lives of propranolol. Finally, translational performance was evaluated by scaling preclinical datasets, where the mPBPK model derived from three common preclinical species provided reasonable predictions of human IV PK profiles. Collectively, these findings provide a clearer physiological interpretation of propranolol disposition across species. Building upon the previous efforts using mPBPK modeling, the current study demonstrates a more mechanistically informed, refined workflow for interspecies scaling and translational human PK prediction applicable to drug candidates.

Mitochondrial transplantation has emerged as a promising therapeutic strategy for neurological diseases associated with mitochondrial dysfunction. However, its application to central nervous system (CNS) disorders remains limited by the restrictive nature of the blood-brain barrier (BBB). Here, we report neutrophil-like mitochondria (nePM@Mito), engineered by coating isolated mitochondria with neutrophil plasma membranes to facilitate CNS delivery. By presenting neutrophil-derived surface adhesion molecules, nePM@Mito interact with endothelial receptors and recapitulate key features of neutrophil transendothelial migration, facilitating BBB crossing via endothelial exocytosis. In a mouse model of Parkinson's disease, intravenous administration of nePM@Mito leads to pronounced CNS accumulation and attenuation of oxidative stress. Delivered mitochondria restore mitochondrial function and increase tyrosine hydroxylase expression in dopaminergic neurons of the substantia nigra, resulting in elevated dopamine levels and improved motor performance. Notably, neutrophil membrane functionalization endows mitochondria with CNS-homing capability while preserving their intrinsic biological activity. The neutrophil-like mitochondrial delivery strategy provides a versatile platform for overcoming BBB limitations and offers a promising therapeutic approach for neurodegenerative diseases involving mitochondrial dysfunction.

Lycosin-II (L-II), a 21-amino acid peptide from Lycosa singoriensis venom, exerts antimicrobial activity via membrane depolarization and permeabilization. Subsequent studies identified the analog L-II-3 as a promising antimicrobial therapeutic. Given the pharmacokinetic limitations, such as metabolic instability, often encountered with peptide-based therapeutics, quantitative characterization of the biological stability and degradation mechanisms of L-II-3 is essential for its in vivo translation. Thus, this study aimed to develop and validate a quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for L-II-3 in biological samples and to investigate its degradation mechanisms. Calibration standards in mouse plasma and whole blood were prepared by direct protein precipitation. The assay achieved acceptable accuracy and precision (<15%) across concentration ranges of 100-1,000 nM in both mouse plasma and whole blood. The stability test indicated that L-II-3 was relatively stable in plasma (88.6 ± 6.2% remaining after 60 min) but rapidly disappeared in whole blood (half-life of 19.7 min). Among the various protease inhibitors tested, EDTA and phenanthroline partially prolonged the half-life of L-II-3 in whole blood. Further assessment using cytosolic and ghost membrane fractions prepared from red blood cells (RBCs) indicated that metal-ion-dependent enzymes in the cytosolic fraction are the primary contributors to L-II-3 degradation, with an additional contribution from RBC membrane binding. L-II-3 degradation was also enhanced by microbial proteases secreted from selected microbial strains. This validated LC-MS/MS assay provides a critical tool for upcoming in vivo pharmacokinetic studies of L-II-3 and its analogs, guiding strategies to enhance in vivo circulation time and therapeutic efficacy.

Gut microbial O-demethylation has been reported for plant-derived dietary compounds containing O-methylated aromatic(s). However, the significance of gut microbial O-demethylation in drug metabolism and disposition remains unexplored. This study examined 64 clinically used oral drugs containing one or more methoxylated aromatics for gut microbial O-demethylation using high-resolution mass spectrometry (HRMS). For 35 of the tested drugs, including the anticancer agent etoposide, we detected metabolites corresponding to O-demethylation (i.e., a mass difference of -14 and its multiples) when individual drugs were incubated with mouse cecal contents. We confirmed that the O-demethylated metabolite (M1) of the model drug etoposide is etoposide catechol using HRMS and proton nuclear magnetic resonance spectroscopy. By testing an in-house collection of 56 gut bacteria individually, we identified seven previously unknown gut bacterial species that exhibit etoposide O-demethylating activity. Etoposide anticancer therapy has been associated with an increased risk of acute myeloid leukemia. We demonstrated that M1 is more genotoxic to myeloid cells when it is orally administered to mice, whereas M1 is less cytotoxic against MCF-7 and HeLa cancer cells than the parent etoposide, suggesting that the gut microbiota may contribute to the secondary genotoxicity of etoposide via O-demethylation. Comparative pharmacokinetic analysis of orally administered etoposide in control and antibiotic-treated mice showed that systemic exposure to etoposide increased 1.9-fold, while M1 exposure decreased 3.7-fold in antibiotic-treated mice, suggesting that gut microbial O-demethylation is a significant determinant of etoposide metabolism and disposition. Collectively, our study reveals the prevalence of gut bacteria with O-demethylation activity, illustrates the contribution of gut microbial O-demethylation to altering drug efficacy and toxicity with the model drug etoposide, and provides a knowledge basis for in-depth characterization of other drugs identified as being susceptible to gut microbial O-demethylation.

Introduction: MG1113 is a humanized immunoglobulin G4 antibody targeting the Kunitz-type protease inhibitor 2 domain of tissue factor pathway inhibitor (TFPI) and is under clinical investigation for hemophilia treatment. This study aimed to refine a previously developed target-mediated drug disposition (TMDD) model for MG1113 by incorporating both targets [e.g., soluble TFPI-α (sTFPI-α) and membrane-bound TFPI (mTFPI)] and a transit compartment to capture delayed absorption after subcutaneous (s.c.) dosing. Methods: The refined TMDD model was fitted to the plasma profiles of MG1113 and sTFPI-α in cynomolgus monkeys that received various intravenous and s.c. doses of MG1113 using the Cluster Gauss-Newton Method (CGNM). The optimized model parameters were scaled allometrically and used to simulate the concentration-time profiles of MG1113 and sTFPI-α in rabbits and humans. Results: The refined TMDD model provided an improved model performance overall, compared to the previous model when fitted to monkey data. When extrapolated to rabbits, the model prediction showed a good agreement with the observed MG1113 and sTFPI-α data, supporting its interspecies applicability. In humans, the model prediction suggested that maintaining sTFPI-α suppression below 25% of baseline, a level associated with therapeutic efficacy, could be achieved with a weekly dose of 3.3 mg/kg MG1113. Conclusion: The refined TMDD model better characterized the nonlinear pharmacokinetic and pharmacodynamic profiles of MG1113 across species by incorporating both targets and delayed absorption after s.c. dosing. This model enabled quantitative prediction of sTFPI-α suppression in relation to MG1113 dose and baseline target levels, supporting a rational dose selection for ongoing and future clinical studies.

Introduction: Escitalopram (S-CIT) is commonly prescribed for depression and anxiety in older patients. Previous research has reported that the effect of CYP2C19 polymorphism on S-CIT pharmacokinetics is more pronounced in older adults than in young adults. The current study investigated whether older adults taking S-CIT face a greater risk for CYP2C19-mediated drug-drug interaction (DDI) than young adults. Methods: Using a physiologically-based pharmacokinetic (PBPK) model, we quantitatively compared the risk of CYP2C19-mediated DDIs in older adults taking S-CIT with any of four CYP2C19 inhibitors (omeprazole, esomeprazole, fluconazole, and fluoxetine). These CYP2C19 inhibitors were selected based on their prevalence of co-administration with S-CIT, as determined by a retrospective analysis of the 2019 Korean National Health Insurance Service senior cohort database. Results and Discussion: Our PBPK modeling-based simulations predicted that the extent of DDI incurred by S-CIT would be greater in older adults than in young adults and vary significantly by CYP2C19 phenotypes (extensive, intermediate, and poor metabolizers). Based on the prediction results, we propose CYP2C19 phenotype-guided S-CIT dosing strategies for older adults. Implementing the proposed dosing recommendation may reduce the incidence of potentially inappropriate use of medication and adverse events in older adults prescribed S-CIT.

Target-mediated drug disposition (TMDD) refers to non-linear pharmacokinetic (PK) profiles arising from the saturable interaction between a drug and its ph