Drug Metabolism and Disposition最新文献

{"title":"Functional characterization of rare DPYD variants identified in 8,380 Japanese individuals: implications for 5-fluorouracil metabolism.","authors":"Kento Terauchi, Eiji Hishinuma, Akiko Ueda, Shota Nishihara, Sakae Saito, Shu Tadaka, Kengo Kinoshita, Masamitsu Maekawa, Nariyasu Mano, Yuu Miyauchi, Masahiro Hiratsuka","doi":"10.1016/j.dmd.2026.100408","DOIUrl":"https://doi.org/10.1016/j.dmd.2026.100408","url":null,"abstract":"<p><p>Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme in the metabolism of 5-fluorouracil, and reduced DPD activity resulting from DPYD genetic variants is a major cause of severe 5-fluorouracil -induced toxicity. Although several clinically relevant variants have been identified in Caucasian populations, the functional consequences of rare DPYD variants identified in Japanese individuals remain poorly characterized. In this study, we comprehensively analyzed 26 DPYD variants identified through whole-genome sequencing of 8380 Japanese individuals. Recombinant DPD proteins were expressed in 293FT cells, and enzymatic activity was evaluated using liquid chromatography-tandem mass spectrometry to determine kinetic parameters (K_m, V_max, CL_int). Protein expression levels and quaternary structure were assessed by immunoblotting and blue native PAGE, and structural modeling was performed to explore possible structural consequences of selected variants. Among the 26 DPD variants analyzed, 5 exhibited markedly reduced or abolished enzymatic activity compared with wild-type DPD, including 3 loss of function variants. Loss of detectable homodimer formation was observed in Gly194Asp and Glu386Ter, whereas other functionally impaired variants retained homodimer formation, indicating that altered dimerization represents only one potential mechanism contributing to DPD dysfunction. Structural analyses suggested possible local alterations affecting cofactor interactions or the dimer interface in selected variants, providing hypotheses for future mechanistic investigation. These findings provide a comprehensive functional characterization of rare DPYD variants identified in Japanese individuals and support their prioritization for future clinical validation. However, their clinical significance and potential utility for fluoropyrimidine dose individualization require confirmation in patients receiving fluoropyrimidine-based chemotherapy. SIGNIFICANT STATEMENT: This study functionally characterized 26 rare DPYD variants identified in a Japanese population and identified 5 variants with markedly reduced or abolished DPD activity. These findings expand the functional annotation of DPYD variation in a population in which established fluoropyrimidine-associated risk variants are uncommon and provide evidence to prioritize functionally impaired variants for future clinical validation.</p>","PeriodicalId":11309,"journal":{"name":"Drug Metabolism and Disposition","volume":"54 11","pages":"100408"},"PeriodicalIF":3.6,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149164133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of nonspecific binding to membrane vesicles on unbound IC₅₀ estimation for P-glycoprotein and breast cancer resistance protein inhibitors and implications for drug-drug interaction risk assessment.","authors":"Renjie Zhan, Richard Moulton, Scott Tallman, Shelby Hullett, Sangwoo Ryu, Michael Mohutsky, Maria Posada, Bridget Morse, Chester Costales","doi":"10.1016/j.dmd.2026.100411","DOIUrl":"https://doi.org/10.1016/j.dmd.2026.100411","url":null,"abstract":"<p><p>P-glycoprotein and breast cancer resistance protein are key efflux transporters relevant to drug-drug interactions (DDIs) for orally administered drugs. The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use M12 guidance recommends using unbound in vitro inhibition potency (IC_50,u) for clinical risk assessment, yet the influence of nonspecific binding to membrane vesicles remains uncharacterized. Herein, vesicle binding for a panel of efflux transporter inhibitors was systematically quantified using equilibrium dialysis and compared with conventional microsomal binding. Nonspecific binding to vesicles reduced free inhibitor concentrations, resulting in right-shifted IC₅₀ values, particularly for high-binding compounds (itraconazole and dronedarone) compared with low-binding compounds (telmisartan) in breast cancer resistance protein assays with Sf9 control vesicles. Similar right shifts were observed for P-glycoprotein inhibition assays with human embryonic kidney 293 control vesicles, although less pronounced. Correction of IC₅₀ values across different vesicle concentrations generally resulted in aligned IC_50,u values. Microsomal binding correlated strongly (Pearson correlation coefficient = 0.965) with vesicle binding, supporting its use as a surrogate for binding correction. Incorporating binding-corrected IC₅₀ values into static DDI risk calculations increased false positives but did not affect false negatives. These findings demonstrate that accounting for fraction unbound in vesicle-based assays can substantially influence the estimation of in vitro inhibitory potency and subsequent static DDI risk assessment. SIGNIFICANT STATEMENT: This study systematically characterizes nonspecific binding to membrane vesicles in P-glycoprotein and breast cancer resistance protein inhibition assays and demonstrates its substantial impact on IC₅₀ determination. The strong correlation between vesicles and microsomal binding provides a practical surrogate for implementing International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use M12 unbound potency recommendations for vesicle-based inhibition assays.</p>","PeriodicalId":11309,"journal":{"name":"Drug Metabolism and Disposition","volume":"54 11","pages":"100411"},"PeriodicalIF":3.6,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149166177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"When microbial drug metabolism becomes a drug disposition variable.","authors":"Rebecca Lewandowski","doi":"10.1016/j.dmd.2026.100407","DOIUrl":"https://doi.org/10.1016/j.dmd.2026.100407","url":null,"abstract":"<p><p>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.</p>","PeriodicalId":11309,"journal":{"name":"Drug Metabolism and Disposition","volume":"54 10","pages":"100407"},"PeriodicalIF":3.6,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149105709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Liposomal encapsulation redirects the in vivo disposition of paclitaxel: a comparative pharmacokinetic, tissue distribution, and excretion study in rats.","authors":"Guolei Zhang, Ning Zhang, Yu Miao, Yidan Zhang, Lei Yin, Meiyun Shi","doi":"10.1016/j.dmd.2026.100406","DOIUrl":"https://doi.org/10.1016/j.dmd.2026.100406","url":null,"abstract":"<p><p>Paclitaxel (PTX) is a potent chemotherapeutic agent for solid malignancies. However, its poor aqueous solubility necessitates toxic solubilizers in conventional formulations, which lead to adverse reactions and unpredictable pharmacokinetics. Liposomal encapsulation offers a biocompatible alternative to overcome these limitations. In this study, a sensitive ultrafiltration coupled with ultra-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous determination of free and total PTX in biological samples. This method was applied to compare the pharmacokinetic behavior of liposomal PTX (PTX-Lip) and conventional PTX injection in rats. Despite receiving a double dose (10 mg/kg), rats treated with PTX-Lip exhibited significantly lower dose-normalized initial concentration (C₀/Dose) and systemic exposure (AUC_(0-∞)/Dose) along with a prolonged elimination half-life (t_1/2) compared with the conventional formulation (5 mg/kg), indicating sustained release. Tissue distribution studies revealed extensive and persistent accumulation of PTX-Lip in the spleen and liver, consistent with reticuloendothelial system uptake, whereas distribution to other tissues was reduced. Excretion profiling demonstrated a fundamental shift in clearance pathways, from combined renal/hepatobiliary elimination for conventional PTX to predominantly hepatobiliary fecal excretion for PTX-Lip, with cumulative fecal recovery reaching 39.27% of the dose, a 2.4-fold increase over the conventional group (16.50%). Collectively, these findings illustrate how liposomal encapsulation modifies the in vivo disposition of PTX through reticuloendothelial system-mediated sequestration, controlled drug release, and rerouted elimination. These descriptive observations, generated in healthy rats without pharmacodynamic or efficacy endpoints, provide a pharmacokinetic reference for the rational design of liposomal nanomedicines. However, these findings should be interpreted as a baseline pharmacokinetic characterization rather than as evidence of therapeutic benefit, and they are intended to generate hypotheses for validation in appropriate disease models with efficacy and safety endpoints. SIGNIFICANT STATEMENT: This study established an ultra-performance liquid chromatography-tandem mass spectrometry method for simultaneous determination of free and total paclitaxel and provided a descriptive characterization of formulation-associated differences in pharmacokinetics, tissue distribution, and excretion. These findings offer a pharmacokinetic reference that may inform the rational design and evaluation of lipid-based nanomedicines in future studies.</p>","PeriodicalId":11309,"journal":{"name":"Drug Metabolism and Disposition","volume":"54 10","pages":"100406"},"PeriodicalIF":3.6,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149105591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soluble epoxide hydrolase research, international collaboration, and translational capacity in Brazil: the scientific legacy of Bruce D. Hammock.","authors":"Wellington Francisco Rodrigues, Carlos Antônio Trindade-da-Silva, Camila Botelho Miguel, Aristóteles Góes-Neto, Christophe Morisseau, Carlos Ueira-Vieira","doi":"10.1016/j.dmd.2026.100403","DOIUrl":"https://doi.org/10.1016/j.dmd.2026.100403","url":null,"abstract":"&lt;p&gt;&lt;p&gt;The recent passing of Bruce D. Hammock provides a timely opportunity to examine how his contributions to soluble epoxide hydrolase (sEH) biology, inhibitor development, and translational pharmacology extended through international scientific collaboration and mentorship. This minireview examines the Brazilian scientific network associated with Hammock as a descriptive case study and combines an independent structured evidence survey of international research-capacity initiatives with curated PubMed records, information from the Brazilian Currículo Lattes repository, and documentary evidence of scientific exchange and mentorship. Temporal, title-term, geographic, documentary, and mentorship analyses were conducted using reproducible workflows. Of 500 records screened in the evidence survey, 24 bibliographically verified unique records were retained after postsearch audit; collectively, they reported associations between sustained international partnerships and researcher training, institutional strengthening, and scientific production. These records provided comparative context and were not required to involve Hammock or members of his scientific network. PubMed retrieval yielded 17 unique indexed records. Thirteen met the criteria for the core Brazilian sEH/(1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea [TPPU]) corpus, 3 were retained as contextual records, and 1 was excluded from the core corpus because it did not address sEH or epoxide hydrolase biology. The core corpus remained anchored in sEH inhibition and lipid-mediator biology, while extending into pain, intestinal injury, arthritis, periodontal inflammation, alveolar bone loss, immune regulation, eicosanoid profiling, macrophage plasticity, and osteoblast metabolism. Brazilian institutional participation in the core publication corpus was concentrated in São Paulo, with additional participation from Minas Gerais and Paraná. The broader documentary analysis identified 43 academic outputs explicitly linked to sEH, TPPU, or the defined Brazilian scientific lineage, together with evidence of scientific exchange, access to pharmacological tools, formal mentorship, and multigenerational propagation of the research trajectory. Together, these findings support the interpretation that Hammock's legacy in drug metabolism and disposition extended beyond foundational discoveries and publications to include the local adaptation of a mechanistically coherent translational research program. More broadly, this case illustrates how pharmacological innovation, accessible experimental tools, and sustained scientific mentorship may support the development of research capacity in emerging scientific settings. SIGNIFICANT STATEMENT: Using the Brazilian network associated with Bruce D. Hammock as a case study, this minireview connects advances in soluble epoxide hydrolase biology and inhibitor development with the documented temporal development of the publication corpus, diversification of ","PeriodicalId":11309,"journal":{"name":"Drug Metabolism and Disposition","volume":"54 10","pages":"100403"},"PeriodicalIF":3.6,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Redefining the Michaelis-Menten kinetics mechanistic basis and derivation in drug metabolism, pharmacology, biochemistry, chemistry, and pharmacokinetics.","authors":"Leslie Z Benet, Jasleen K Sodhi","doi":"10.1016/j.dmd.2026.100402","DOIUrl":"10.1016/j.dmd.2026.100402","url":null,"abstract":"<p><p>Since the recognition of chemical rates of reaction 175 years ago, all derivations of rate constants in drug metabolism, pharmacology, biochemistry, chemistry, as well as clearance values in pharmacokinetics and clinical medicine require solving differential equations based on mechanistic hypotheses at steady state. This approach leads to mostly consistent, but not always, operational results for linear systems but introduces numerous ambiguities and unnecessary and unsupported quasi-steady-state assumptions for nonlinear systems. Yet, thousands of papers and all textbooks describing kinetics in drug metabolism, pharmacology, biochemistry, and pharmacokinetics accept these assumptions. We demonstrate that correctly combining parallel and in series rate-defining kinetic processes enables simple derivation for both in vitro and in vivo linear and here, Michaelis-Menten nonlinear systems. Using this new methodology, we derive the Michaelis-Menten equation requiring no assumption regarding (1) the mechanism of the substrate-enzyme interaction, (2) steady state or quasi-steady state believed necessary to solve the differential equations first presented 100 years ago, (3) the ratio of enzyme-to-substrate concentrations, (4) the order, and (5) reversibility (or lack of reversibility) of the enzyme-substrate complex. We demonstrate that the new methodology gives the same outcome as the traditional differential equation derivation for the in vivo impact of hepatic blood flow for high clearance compounds, such as ethanol. The proposed methodology is independent of differential equations and mechanistic constraints, and is applicable to all linear and nonlinear kinetic processes in vitro and in vivo, greatly simplifying characterization and teaching of kinetic concepts. SIGNIFICANCE STATEMENT: Adapting Kirchhoff's laws (from physics), one may very simply derive equations for parallel and in series kinetic processes, for both linear and Michaelis-Menten nonlinear systems, without relying on differential equations and their associated assumptions. Contrary to the universally accepted position, the Michaelis-Menten equation appears to be valid independent of quasi-steady-state assumptions and mechanistic hypotheses regarding enzyme-substrate interactions, such as how many substrate molecules interact with the enzyme or the reversibility of the product to the enzyme-substrate complex.</p>","PeriodicalId":11309,"journal":{"name":"Drug Metabolism and Disposition","volume":"54 10","pages":"100402"},"PeriodicalIF":3.6,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149126850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Submicellar aggregates of deoxycholate and glycodeoxycholate suppress in vitro CYP3A oxidation via membrane perturbation.","authors":"Cuitong Wang, Qi Chen, Ke Lan","doi":"10.1016/j.dmd.2026.100399","DOIUrl":"https://doi.org/10.1016/j.dmd.2026.100399","url":null,"abstract":"<p><p>Cytochrome P450 3A4 (CYP3A4) and 3A7 (CYP3A7) specifically catalyze the 1β- and 5β-hydroxylation of deoxycholic acid (DCA) and glyco-DCA (GDCA). Their oxidation rates in microsomal and recombinant CYP3A4/3A7 conform to the Hill kinetic model at low substrate concentrations of up to 400 and 250 μM for DCA and GDCA, respectively, but decline progressively at submicellar concentrations, culminating in complete enzyme deactivation at or above the critical micelle concentration. We hypothesized that this atypical kinetic behavior originates from the disruption of microsomal vesicles by submicellar assemblies of DCA/GDCA. Transmission electron microscopy revealed that submicellar DCA did not compromise vesicle integrity, whereas membrane disruption became evident at or above 1000 μM. Spectroscopic analyses (UV, NMR, and bilirubin-probed fluorescence) determined the critical micelle concentration of both bile salts at approximately 1000 μM and informed the presence of oligomers below this threshold. Notably, at the concentrations of oligomer formation, DCA/GDCA exhibited no inhibitory effect on cytosolic sulfotransferase; however, they markedly suppressed the membrane-associated activities of CYP1A2 and CYP2D6, as probed by phenacetin and dextromethorphan oxidation, respectively. This differential susceptibility between cytosolic and vesicle-bound enzymes corroborates the proposed vesicle membrane-dependent mechanism. Collectively, our findings strongly suggest that submicellar DCA and GDCA autoinhibit their CYP3A-catalyzed oxidation through a mechanism that involves a vesicle membrane-dependent mechanism, with their self-assembly being intrinsically linked to the observed anomalous kinetics. SIGNIFICANCE STATEMENT: This work demonstrates that submicellar deoxycholate and glycodeoxycholate autoinhibit CYP3A oxidation via membrane perturbation, not substrate sequestration. Spectroscopic detection of bile salt oligomers below the critical micelle concentration correlates with suppression of multiple membrane-bound P450s (CYP1A2/2D6/3A) while sparing cytosolic sulfotransferase, indicating that submicellar bile salts impair electron transfer among P450, P450 reductase, and cytochrome b5. This membrane-dependent mechanism resolves the long-standing atypical kinetics of secondary bile acids and has implications for bile acid-drug interaction assessment, particularly in cholestatic liver disease.</p>","PeriodicalId":11309,"journal":{"name":"Drug Metabolism and Disposition","volume":"54 10","pages":"100399"},"PeriodicalIF":3.6,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149105587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Repaglinide metabolism by human hepatocytes reveals CYP2C8 dominance and misassignment of CYP3A4 by liver subcellular fractions and recombinant enzymes.","authors":"Tashinga E Bapiro","doi":"10.1016/j.dmd.2026.100400","DOIUrl":"https://doi.org/10.1016/j.dmd.2026.100400","url":null,"abstract":"<p><p>Repaglinide is an antidiabetic agent and Food and Drug Administration-endorsed clinical CYP2C8 probe with a well characterized human disposition profile in which a dicarboxylic acid, M2, is the main metabolite accounting for 66% of the administered dose. The remainder is distributed among M1 (4%), unchanged repaglinide (2%), M4 (<0.5%), several minor metabolites (each <1%), and some unidentified metabolites. Although substantial in vivo evidence supports repaglinide as a CYP2C8 probe, in vitro studies indicate a greater CYP3A4 contribution to its overall metabolism. Previous research using chemical inhibitors in human liver subcellular fractions and recombinant enzymes consistently assigned M1 and M4 formation to CYP3A4 and CYP2C8, respectively, with M2 predominantly formed via a CYP3A4-mediated first-step and subsequent completion by a cytosolic enzyme. However, corresponding experiments using chemical inhibitors were not conducted in human hepatocytes (HH). Motivated by our recent data indicating potential misassignment of CYP3A4 involvement by human liver microsomes and recombinant enzymes, this study compared these matrices with HH. Here, human liver microsomes, liver S9, and recombinant enzymes also assigned M1 and M4 formation to CYP3A4 and CYP2C8, respectively. In contrast, slightly over half of M1 formed in HH was attributed to CYP2C8, a surprising result given the enzyme's lower hepatic expression and minimal contribution in subcellular fractions. M4 formation remained predominantly CYP2C8-dependent in HH. Crucially, and contrary to results in subcellular fractions, HH showed minimal CYP3A4 involvement in the formation of the major in vivo metabolite M2, firmly establishing CYP2C8 as the primary enzyme. These findings provide robust data for rationalizing repaglinide pharmacokinetics and demonstrate a real risk of CYP3A4 misassignment when relying solely on liver subcellular fractions or recombinant enzymes. SIGNIFICANCE STATEMENT: The author and colleagues recently discovered that human liver microsomes and recombinant enzymes can misidentify CYP3A4 as the main savolitinib-metabolizing enzyme. It is, therefore, crucial for researchers and regulatory authorities to understand the risk of misassignment. This study shows that the same phenomenon underlies the inconsistent in vitro-in vivo relative contributions of CYP3A4 and CYP2C8 to repaglinide metabolism that have been difficult to explain and demonstrates that liver subcellular fractions and recombinant enzymes pose a real risk for enzyme misidentification.</p>","PeriodicalId":11309,"journal":{"name":"Drug Metabolism and Disposition","volume":"54 10","pages":"100400"},"PeriodicalIF":3.6,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149105531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Systematic evaluation of five classical mechanistic methods for tissue-plasma partition coefficients across diverse tissues and compound classes.","authors":"Jia Geng, Ammara Ayub, Feifan Xie","doi":"10.1016/j.dmd.2026.100405","DOIUrl":"https://doi.org/10.1016/j.dmd.2026.100405","url":null,"abstract":"<p><p>Tissue-plasma partition coefficient (K_p) is a key parameter governing drug distribution and the predictive accuracy of physiologically based pharmacokinetic models. Although several classical mechanistic methods have been developed for K_p prediction, systematic comparisons across multiple tissues and compound classes remain limited. In this study, we systematically compared 5 classical mechanistic methods using a standardized rat dataset to assess their predictive performance and applicability. A PubMed literature search was performed to compile a dataset of 781 K_p values from 119 compounds across 11 rat tissues, covering 6 compound classes. Physicochemical properties were collected from literatxure and public databases. Five mechanistic methods-Poulin and Theil, Berezhkovskiy, Rodgers and Rowland, Willmann, and Schmitt-were implemented in R software (R Foundation for Statistical Computing) according to their published algorithms. Predictive performance was evaluated using 3-fold error proportion, average fold error, absolute average fold error, and root mean square error. Overall, the Rodgers and Rowland method performed the best (68.63% within 3-fold error; absolute average fold error = 2.62, average fold error= 0.82). Across compound classes, the Rodgers and Rowland method was superior for most classes, particularly strong bases (74.24% within 3-fold error), whereas the Poulin and Theil method performed better for neutral compounds (71.15% within 3-fold error). Across tissues, predictions were more accurate for skin and heart, whereas kidney, adipose, and brain remained challenging. These findings indicate that K_p prediction performance varies substantially across different in silico methods, compound classes, and tissue types. SIGNIFICANCE STATEMENT: This study systematically evaluates 5 classical mechanistic methods for predicting tissue-plasma partition coefficients across 11 rat tissues and 6 compound classes using a standardized dataset of 781 values. Our findings identify the most accurate and robust method, reveal compound-specific and tissue-specific limitations, and provide practical guidance for physiologically based pharmacokinetic modeling, supporting improved drug distribution prediction in preclinical research and drug development.</p>","PeriodicalId":11309,"journal":{"name":"Drug Metabolism and Disposition","volume":"54 10","pages":"100405"},"PeriodicalIF":3.6,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149105580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interindividual variability in hepatic hydrolytic enzymes: Effects of age, sex, and race on the abundance of drug-metabolizing hydrolases.","authors":"Dilip Kumar Singh, Deepak Ahire, Scott Heyward, Robert S Jones, S Cyrus Khojasteh, Ryota Kikuchi, Priyanka Kulkarni, Bin Ma, Bernard P Murray, Bill J Smith, David M Stresser, Mitchell E Taub, Ting Wang, Bhagwat Prasad","doi":"10.1016/j.dmd.2026.100401","DOIUrl":"https://doi.org/10.1016/j.dmd.2026.100401","url":null,"abstract":"<p><p>Hydrolases represent a diverse class of drug-metabolizing enzymes that catalyze the hydrolytic cleavage of a broad spectrum of xenobiotics including certain novel drug modalities, thereby modulating pharmacokinetics and potentially influencing pharmacodynamics. However, many hydrolases remain poorly characterized, and their developmental expression and interindividual variability are not well understood. This study aimed to systematically characterize hydrolase expression in the human liver. Human hepatocytes obtained from 8 adult and 50 pediatric donors were subjected to global proteomics analysis to quantify hydrolase abundance and assess variability across demographic factors. Two hundred and thirty-nine hydrolases were studied for the influence of age, sex, and race on their abundance. The key enzymes included arylacetamide deacetylase (AADAC), alpha/beta hydrolase domain-containing protein 10 (ABHD10), alkaline phosphatase, tissue-nonspecific isozyme (ALPL), acyl-peptide hydrolase (APEH), bleomycin hydrolase (BLMH), valacyclovir hydrolase (BPHL), cytidine deaminase (CDA), carboxylesterase 1 (CES1), CES2, carboxymethylenebutenolidase homolog (CMBL), cathepsin A (CTSA), cathepsin B (CTSB), dipeptidyl peptidase 4 (DPP4), epoxide hydrolase 1 (EPHX1), EPHX2, EPHX3, guanine deaminase (GDA), paraoxonase 1 (PON1), PON2, PON3, and deoxynucleoside triphosphate triphosphohydrolase SAMHD1 (SAMHD1). Notably, several enzymes exhibited age-dependent increases in the abundance from neonates to adults (fold), including CDA (>200), GDA (53), CES1 (14), EPHX3 (12), ALPL (10), CES2 (3.5), sialate O-acetylesterase (SIAE) (3), and CMBL (2.6). In contrast, BLMH, CTSA, DPP4, PON2, and SAMHD1 displayed approximately 2-fold to 3-fold lower abundance in adults than in neonates. PON1 was 42% higher in Black individuals compared with White individuals, whereas PON3 abundance was 32% higher in males than in females. This study provides the first systematic quantitative characterization of a broad panel of hydrolases and provides a key foundation for physiologically-based pharmacokinetic and quantitative systems pharmacology modeling of the substrates of hydrolytic enzymes. SIGNIFICANCE STATEMENT: Interindividual variability, including ontogeny, is well characterized for many drug-metabolizing enzymes but remains poorly defined for most hydrolases. The influence of age, sex, and race on 239 hepatic hydrolases was evaluated, revealing important demographic determinants. These data provide a critical foundation for physiologically-based pharmacokinetic modeling. Incorporation of proteomics-informed variability into physiologically-based pharmacokinetic models has the potential to improve the prediction of drug pharmacokinetics, particularly in pediatric populations.</p>","PeriodicalId":11309,"journal":{"name":"Drug Metabolism and Disposition","volume":"54 10","pages":"100401"},"PeriodicalIF":3.6,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149135565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}