Microbial transformation of drugs is experimentally established, but no agreed method determines when a detected pathway materially contributes to drug disposition. This minireview proposes a 5-gate framework for evaluating microbial metabolism as a source of drug-disposition variability. Evaluation begins by asking whether drug-related material reaches a microbial compartment, whether a defined drug-specific problem exists, and whether confirmation could change a development or therapeutic decision. Candidates then require demonstration of a defined microbial function, confirmation of an in vivo drug-specific consequence, comparison of effect magnitude with a prespecified pharmacologic benchmark, and evidence that the microbial measure improves prediction or decision-making beyond established covariates. The benchmark serves as the drug-specific denominator for interpreting microbial effect size. Route and formulation determine substrate access, sampling compartment, assay selection, and the relevant disposition endpoint. Transformation catalogs and genome-scale community models can prioritize pathways and estimate population heterogeneity, but predicted capacity is not equivalent to expressed activity, realized flux, or altered human exposure. A worked digoxin example compares the maximum reported increase of approximately 2-fold in serum concentration after suppression of microbial inactivation with recognized digoxin drug interactions. The framework complements existing microbiome tools by defining when mechanistic findings justify targeted drug-metabolism, pharmacokinetic, or drug-development evaluation. Microbial metabolism becomes a drug-disposition variable when measured function produces a reproducible, quantitatively material effect on drug behavior and provides information beyond established covariates. SIGNIFICANCE STATEMENT: Microbial biotransformation is increasingly detectable, but detection alone does not establish that microbial activity materially alters drug disposition. This minireview proposes a 5-gate framework that connects microbial-compartment exposure and demonstrated function to an in vivo drug-specific consequence, compares effect magnitude with a prespecified pharmacologic benchmark that serves as the drug-specific denominator, and requires incremental predictive or decision value before microbial measures advance beyond targeted drug-development evaluation.

Osteoarthritis (OA) is a chronic degenerative joint disease and a leading cause of disability worldwide, yet no disease-modifying therapies are currently available. The role of synovial macrophages in OA pathogenesis remains incompletely understood, and the molecular mechanisms by which they drive cartilage destruction have not been fully elucidated. By integrating human OA microarrays, synovial single-cell RNA-seq, and multi-level validation, we identified lymphocyte-specific protein 1 (LSP1) as a macrophage-specific hub gene upregulated in OA. Mechanistically, LSP1 directly binds to and inhibits superoxide dismutase 1 (SOD1), inducing a redox imbalance that concurrently activates the NADPH oxidase (NOX) and mitochondrial reactive oxygen species (mtROS) pathways. This cascade drives the release of macrophage extracellular traps (METs), which directly damage chondrocytes and accelerate OA progression. Virtual screening of the DrugBank database identified the cardiac glycoside digoxin as a compound that competitively binds LSP1, restores SOD1 activity, and suppresses the NOX/mtROS-METs axis. This study defines a novel LSP1-SOD1-METs pathogenic axis in OA and nominates digoxin as a repurposable therapeutic candidate. Unlike its previously reported cartilage-targeting mechanism, digoxin alleviates OA by suppressing synovial inflammation via LSP1 targeting, highlighting its dual-target potential for concurrent modulation of synovial and cartilage pathology.

This study characterized the pharmacokinetic interaction between Compound Danshen Tablets (CDT) and atorvastatin (ATV) and investigated absorption- and transporter-related mechanisms underlying this interaction. ATV pharmacokinetics were evaluated after oral and intravenous administration in normal and hyperlipidemic/diabetic rats, with or without repeated CDT treatment. Mechanistic studies included single-pass intestinal perfusion, Caco-2 bidirectional transport assays, human multidrug resistance protein 1 inside-out vesicle transport assays, ileal P-glycoprotein (P-gp) immunoblotting, an in vivo digoxin probe-substrate experiment, and molecular docking. Repeated CDT administration increased oral ATV exposure in both normal and model rats, with the area under the plasma concentration-time curve from 0 to 24 hours and maximum plasma concentration increasing by up to 85.83% and 306.53%, respectively, whereas intravenous ATV pharmacokinetics were not significantly altered. In Caco-2 monolayers, ATV exhibited marked directional efflux, with an efflux ratio of 39.32, which was reduced to 10.99 by verapamil. CDT increased the apical-to-basolateral apparent permeability coefficient of ATV from 0.41 to 1.31 × 10[-6] cm/s and reduced the efflux ratio to 9.82, whereas the basolateral-to-apical apparent permeability coefficient decreased from 16.27 to 12.90 × 10[-6] cm/s. In human multidrug resistance protein 1 inside-out vesicles, CDT concentration dependently reduced ATP-dependent N-methylquinidine transport, with inhibition rates ranging from 24.97% to 80.45% at 50-800 μg/mL. Together with the ileal P-gp protein data and the digoxin probe-substrate experiment, these findings indicate that CDT enhances intestinal absorption of ATV primarily by attenuating intestinal P-gp-mediated efflux through reducing both P-gp transport activity and protein abundance. These results provide mechanistic evidence that modulation of intestinal efflux transport contributes to the increased systemic exposure of ATV after repeated CDT administration. SIGNIFICANT STATEMENT: This study identifies a clinically relevant herb-drug interaction in which repeated administration of compound Danshen tablets increases oral atorvastatin exposure in normal and hyperlipidemic/diabetic rats without materially altering intravenous atorvastatin pharmacokinetics. Integrated pharmacokinetic, single-pass intestinal perfusion, Caco-2 transport, human multidrug resistance protein 1 vesicle, ileal P-glycoprotein, and digoxin probe-substrate data support attenuation of intestinal P-glycoprotein-mediated efflux, through reduced transporter activity and protein abundance, as a mechanism enhancing atorvastatin absorption.

A novel method of in-situ functionalized magnetic dispersive solid phase microextraction was established and coupled with high performance liquid chromatography-ultraviolet detection to determine four cardiac glycosides in human plasma. The adsorbent was prepared by in-situ functionalization of Fe3O4/SBA-15 with surfactant during the extraction process. The synthesized material was characterized using N2 physisorption, infrared spectroscopy, transmission electron microscopy, and vibrating sample magnetometry. Key parameters affecting extraction efficiency, including type of surfactant, concentration and volume of hexadecyl trimethyl ammonium bromide, adsorbent dosage, pH of sample solution, salt addition, extraction time, elution program, were systematically evaluated and optimized. The method demonstrated good linearity, satisfactory lower limit of quantification (deslanoside at 8.0 ng/mL, lanatoside C at 2.0 ng/mL, digoxin and digitoxin each at 1.6 ng/mL), high precision (RSD between 0.6% and 9.0%), good accuracy (RE within -8.8% to 11%), and acceptable extraction recoveries (56.1%-70.3%) under optimal conditions. Additionally, the method showed no significant matrix effect in human plasma, and the stability of the analytes was confirmed. The proposed method features simple and convenient adsorbent preparation and extraction processes, as well as high extraction efficiency for cardiac glycosides, making it a promising approach for trace analysis in complex matrices.

UBE2C (Ubiquitin-Conjugating Enzyme E2C) is an E2 ubiquitin-conjugating enzyme involved in the ubiquitin-proteasome system which plays a crucial role in protein degradation and regulation of cell cycle. Overexpression of UBE2C can lead to mitotic defects, genomic instability and uncontrolled cell division, contributing to tumorigenesis. Overexpression of UBE2C in multiple cancers and its association with enhanced tumor progression, metastasis and drug resistance has led to its consideration as a potential therapeutic target. We report association of high UBE2C expression with poor overall survival across cancers, present p53-status-stratified expression analysis, determine its essentiality based on dependency scores in multiple cancer cell lines, association with immune cell infiltration, and analyze the effect of UBE2C silencing on cancer pathways, thus corroborating it as a viable pan-cancer target. We then identify potential UBE2C targeting repositioned therapeutics at both mRNA and protein levels by employing structure-based virtual screening, using CMap database, ceSAR based sig2lead application, and performing molecular dynamic simulations. Finally, we provide the effect of selected compounds on cell viability in NCI60 panel of cancer cell lines from different tissue origins. The compounds anisomycin, cephaeline, digitoxin, mitoxantrone, digoxin, digitoxigenin, homoharringtonine, NCI724448, midostaurin, withaferin A and NCI718581 were found to be effective UBE2C targeting candidates which could result in significant growth inhibition at low doses across multiple cell lines. Our results lay a strong groundwork for further preclinical exploration of the efficacy of these compounds against different cancers individually as also in combination with existing therapeutics for their future development as novel anticancer drugs.

In vitro intestinal models such as Caco-2 cells are integral to pharmacokinetic research. However, insect intestinal cells have proven less tractable for pharmacokinetic studies limiting our knowledge of pesticide pharmacokinetics in these species. To overcome this, we have developed a Caco-2 cell line that has been genetically modified to express insect P-glycoprotein (Pgp), providing a robust 'insectified' screening platform to monitor xenobiotic transport. This platform consists of wild-type (Pgpwild type) cells, a Pgp knockout (PgpKO) line which eliminates endogenous background interference, and species-specific Pgp rescue lines. These rescue lines allow for the stable expression of human (Hs Pgp), cotton bollworm (Ha Pgp), and malaria mosquito (Ag Pgp) homologs, enabling direct comparisons of efflux kinetics across different pesticides and species. Functional validation using the substrate Digoxin confirmed high Pgp dependency within the platform. Methyl parathion, an organophosphate insecticide, was recognized and transported by both insect and human Pgps consistent with the low mammalian selectivity of this compound. In contrast, Triflumezopyrim exhibited a high efflux ratio that remained remarkably stable even in the absence of MDR1, indicating that the uptake and pharmacokinetics of this compound are not Pgp-dependent. By successfully differentiating between transporter-specific and independent pathways, these cell lines can serve as a high-fidelity screening tool for predicting novel pesticide selectivity and possibly validating the potential role of transporters in resistance. Future work can extend this system to other transporters.

Background/Objectives: Atrial fibrillation (AF) and heart failure with reduced ejection fraction (HFrEF) frequently coexist and are linked by shared risk factors and pathophysiological mechanisms. Their association is consistently related to worse clinical outcomes. This narrative review summarizes current evidence regarding the epidemiology, pathophysiology, management strategies, and prognosis of patients with AF and HFrEF. Methods: This is a narrative review based on published randomized trials, registries, and observational studies evaluating the interaction between AF and HFrEF, with a focus on therapeutic strategies including rate and rhythm control, catheter ablation, stroke prevention, and guideline-directed medical therapy. Results: AF and HFrEF have a bidirectional relationship, with each condition promoting the development and progression of the other. AF contributes to hemodynamic impairment and adverse remodeling, while HFrEF promotes atrial structural and electrical changes. Management remains complex. Rate control is commonly achieved with beta-blockers and digoxin, while rhythm control is limited by the safety profile of antiarrhythmic drugs. Catheter ablation has shown improvements in left ventricular function and, in selected patients, reductions in hospitalizations and mortality, although results are not consistent across all trials. Guideline-directed medical therapy improves outcomes in HFrEF, but its interaction with AF varies across drug classes. Stroke risk is significantly increased, requiring appropriate anticoagulation. Patients with AF and HFrEF have an increased risk of mortality, hospitalization, and adverse clinical events compared with those with either condition alone, although the extent to which these outcomes are attributable to AF itself, HF severity, or the associated comorbidity burden remains uncertain. Conclusions: The coexistence of AF and HFrEF identifies a high-risk population with complex management and unfavorable outcomes. While advances in rhythm control and heart failure therapies have improved selected outcomes, optimal treatment strategies and their impact on long-term prognosis remain incompletely defined.

The Na[+]/K[+]-ATPase consumes a substantial portion of cellular ATP to maintain essential electrochemical gradients, yet its role in regulating cancer cell proliferation and phenotypic plasticity remains complicated by its dual function as an ion transporter and a scaffolding receptor. Here, we investigate the physiological consequences of pharmacological NKA blockade using digoxin in K562 human chronic myelogenous leukemia cells. Submicromolar digoxin exposure induced a concentration-dependent attenuation of cell proliferation (IC50=151.0 nM) and a statistically significant depression of metabolic reducing capacity without impairing cell viability. Competitive supplementation with extracellular potassium salts produced a surmountable rightward shift in digoxin sensitivity, confirming that growth inhibition is driven by on-target NKA pump occupancy rather than non-specific interactions. Furthermore, this cytostatic growth attenuation and metabolic depression were found to be fully reversible upon drug clearance. K562 cells are largely refractory to canonical kinase-overdrive stress checkpoints as they harbor constitutive BCR-ABL tyrosine kinase activity alongside non-functional TP53 and a homozygous deletion of CDKN2A (p16[INK4a]). Consequently, these findings suggest that NKA perturbation attenuates K562 growth primarily through ion dyshomeostasis and secondary active transport constraints rather than scaffold-mediated signaling. Overall, we present a novel model for elucidating the role of the NKA in cancer proliferation and dissecting the mechanistic underpinnings of ion-mediated alterations in cancer cell physiology.

Because P-glycoprotein (P-gp) influences the disposition of substrate drugs, regulatory agencies recommend ascertaining the P-gp substrate status of active pharmaceutical ingredients (API's) intended for humans. Transwell-based assays using P-gp-overexpressing human cell lines are routinely used to predict the API's P-gp substrate status. Although ABCB1-1Δ-mediated P-gp deficiency contributes to serious canine adverse drug reactions, assessment of canine P-gp status is not currently recommended by regulatory agencies for canine API's. We have previously employed a competitive efflux assay to assess drugs as canine P-gp substrates as it affords some advantages over transwell assays. Our objective was to preliminarily compare results generated from these two methods using historical data for transwell assays. Eleven drugs were assessed as canine P-gp substrates by both methods, with two identified as non-P-gp substrates (erythromycin, propranolol) and nine identified as canine P-gp substrates (clarithromycin, daunorubicin, digoxin, etoposide, paclitaxel, quinidine, ritonavir, verapamil, vinblastine). Erythromycin was identified as a canine P-gp substrate by competitive efflux assay at roughly 10-fold higher concentrations than was used for transwell assays. Concordance of these methods assessing canine P-gp substrate status using historical data supports the need for head-to-head studies comparing these two methods for identifying canine P-gp substrates.

Isavuconazonium sulfate is the water-soluble prodrug of the active triazole antifungal agent isavuconazole. Isavuconazonium sulfate is approved for the treatment of invasive aspergillosis and invasive mucormycosis in pediatric and adult populations. In the present analysis, an isavuconazole physiologically-based pharmacokinetic (PBPK) model was built and verified in adult and pediatric populations using the Simcyp[®] simulator. The verified pediatric model was then used to predict the magnitude of DDI risk in pediatric populations vs. adult populations. The simulations conducted were designed to match the observed clinical trials conducted in adults but with pediatric equivalent doses based on clinical guidelines. Based on the results of the analysis, isavuconazole DDI risk was similar between pediatric and adult populations. When the isavuconazole perpetrator DDI simulations were compared to adults, there was a trend of larger geometric mean (GM) AUCinf and Cmax ratios in patients 1 to < 3 years old receiving the 15 mg/kg dose. The GM AUCinf ratio in this study population ranged from 7 to 36% larger than predicted in the adult population. Based on the results of this analysis and literature reports, it is advisable to show greater caution when considering potential DDI in patients < 3-year-old, especially when receiving larger isavuconazonium sulfate doses. In addition, caution should be used in patients < 3 years-old when considering coadministration of isavuconazole with narrow therapeutic index medications such as digoxin and warfarin or medications with large variability in oral bioavailability such as midazolam.