Details of a Researcher - Matsumoto, Kazuaki

Papers - Matsumoto, Kazuaki

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Establishing an assay to evaluate d-amino acid oxidase enzyme kinetics and inhibition using WST-8 redox dye.

Miyake K, Enoki Y, Nakazawa Y, Taguchi K, Matsumoto K

FEBS open bio 2026.02

Joint Work

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Development of a risk prediction model for vancomycin-associated acute kidney injury: a multicentre retrospective study.

Ishigo T, Suzuki A, Ibe Y, Fujii S, Fukudo M, Yoshida H, Tanaka H, Fujihara H, Yamaguchi F, Ebihara F, Maruyama T, Yagi Y, Hamada Y, Samura M, Nagumo F, Komatsu T, Tomizawa A, Takuma A, Chiba H, Nishi Y, Igarashi Y, Enoki Y, Matsumoto K

The Journal of antimicrobial chemotherapy 81 ( 3 ) 2026.02

Joint Work, ISSN 0305-7453

Objectives To clarify the relationship between acute kidney injury (AKI) and vancomycin use in patients with renal impairment and to establish a risk score for AKI. Methods In this retrospective, multicentre, observational cohort study, trough and peak blood samples were collected from patients who initiated vancomycin therapy. The cumulative incidence of AKI within 14 days was compared among three groups classified according to renal function (estimated glomerular filtration rate ≥ 60, 30-59 and <30 mL/min/1.73 m2). The risk score and predicted probability of AKI incidence were calculated. AKI was defined in accordance with the Kidney Disease Improving Global Outcomes criteria. Results The incidence of AKI was 11.7% (99/847). No statistically significant difference was detected in the cumulative incidence of AKI among the three groups (P = 0.103). Cox proportional hazard analysis showed that the use of tazobactam/piperacillin [HR: 3.3, 95% CI (2.18-4.99), 2 points], vasopressors/inotropes [HR: 3.0, 95% CI (2.02-4.51), 2 points] and area under the concentration-time curve (AUC) on Day 2 [500-600 µg·h/mL: HR, 2.4, 95% CI (1.50-3.89), 1 point; >600 µg·h/mL: HR, 4.4, 95% CI (2.62-7.37), 3 points] were significantly related to the development of AKI. The predicted probabilities of AKI incidence were <5% (low-risk), 5% to <20% (moderate-risk), 20% to <40% (high-risk) and 40% to 67% (very high-risk), with total points of 0, 1-2, 3-4 and ≥5, respectively. Conclusions A risk prediction model was developed for AKI based on AUC exposure and concomitant medications, and no difference in AKI risk was observed across renal function categories.

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Application of epithelial lining fluid drug concentrations to MICi-Based PK/PD modeling of cefepime/nacubactam in a murine model of CPE pneumonia

Mizukami Y., Takahashi M., Suzuki K., Duan S., Ikegami S., Muraishi T., Satake N., Okamoto Y., Igarashi Y., Enoki Y., Taguchi K., Matsumoto K.

Journal of Infection and Chemotherapy 32 ( 1 ) 102889 2026.01

Joint Work, ISSN 1341321X

Introduction: Nacubactam is a novel β-lactamase inhibitor with intrinsic antibacterial activity that shows therapeutic potential against carbapenemase-producing Enterobacterales when administered with β-lactam antibiotics. Pharmacokinetics/pharmacodynamics (PK/PD) analyses based on drug concentrations at the site of infection are recommended to better evaluate antibiotic efficacy. A new PD index, the instantaneous minimum inhibitory concentration (MIC<inf>i</inf>), which dynamically reflects the changing susceptibility of β-lactams during co-administration with β-lactamase inhibitors, has recently been proposed. This study aimed to assess the efficacy of cefepime combined with nacubactam in a murine model of pneumonia using MIC<inf>i</inf>-based PK/PD analysis in the lung epithelial lining fluid (ELF). Methods: In vitro pharmacodynamic testing using the checkerboard method was conducted with two β-lactamase-producing Klebsiella pneumoniae strains. In vivo PK and PD studies were performed in neutropenic mice using both β-lactamase-producing and non-producing strains. Drug concentrations in plasma and ELF were measured, and MIC<inf>i</inf>-based PK/PD analysis was conducted. Results: In vitro, the MIC of cefepime decreased in a concentration-dependent manner with increasing nacubactam. In the murine model of pneumonia, cefepime monotherapy resulted in bacterial changes of 0.12–4.30 log<inf>10</inf> CFU/lung, while the combination therapy reduced bacterial counts by −5.93 to −0.234 log<inf>10</inf> CFU/lung. The percentage of time that free cefepime concentrations exceeded MIC<inf>i</inf> (T > MIC<inf>i</inf>) was highly correlated with bacterial reduction. The target T > MIC<inf>i</inf> for maximal effect was estimated to be 29.3 %. Conclusions: These findings support the utility of MIC<inf>i</inf>-based PK/PD analysis for optimizing combination antibiotic therapy in pneumonia.

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Impact of Chronic Kidney Disease on the Onset of Sepsis: A Systematic Review

Osa Sumika, Enoki Yuki, Endo Ayuka, Kumamoto Kanako, Kobayashi Keita, Komiya Chihiro, Satake Natsuki, Kawakami Junichi, Yagi Tatsuya, Taguchi Kazuaki, Matsumoto Kazuaki

Biological and Pharmaceutical Bulletin (The Pharmaceutical Society of Japan) 49 ( 1 ) 99 - 107 2026

Joint Work, ISSN 09186158

Patients with chronic kidney disease (CKD) who develop sepsis experience worse prognoses; however, the impact of CKD on the incidence of sepsis has not been systematically investigated. A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search of Medical Literature Analysis and Retrieval System Online, Web of Science, the Cochrane Register of Controlled Trials, and ClinicalTrials.gov was performed for literature published prior to May 22, 2025, comparing the onset of sepsis in patients with or without CKD. The risk of bias was determined using the Risk of Bias in Nonrandomized Studies of Interventions tool. This study was registered with the International Prospective Register of Systematic Reviews (CRD42023465075). A total of 14 studies met the inclusion criteria for the systematic review. Of these, 5 examined community-acquired sepsis, 2 focused on intensive care unit-acquired sepsis, and the rest investigated surgery-acquired sepsis. Most studies enrolled populations aged over 65 years; 2 assessed age-related sepsis risk. One study evaluated sepsis occurrence in patients with end-stage CKD, while 3 studies stratified this association by estimated glomerular filtration rate (eGFR). Nearly all studies demonstrated an increased risk of sepsis among patients with CKD, with the risk progressively increasing as eGFR declined. Additionally, 2 studies reported that CKD elevated the risk of sepsis regardless of age, and all included studies indicated a low risk of bias. We indicate that patients with CKD may have a higher risk of developing sepsis than individuals without CKD.

Development and external validation of a population pharmacokinetic model and optimal Vancomycin dosing regimen for overweight and obese patients

Komatsu T., Tomizawa A., Samura M., Suzuki A., Ishigo T., Fujii S., Ibe Y., Yoshida H., Tanaka H., Fujihara H., Yamaguchi F., Ebihara F., Maruyama T., Yagi Y., Hamada Y., Nagumo F., Takuma A., Chiba H., Nishi Y., Igarashi Y., Enoki Y., Otori K., Matsumoto K.

Journal of Infection and Chemotherapy 31 ( 12 ) 102838 2025.12

Joint Work, ISSN 1341321X

Introduction: This study aimed to develop and evaluate a population pharmacokinetic model and optimal dosing regimen for vancomycin in overweight and obese adults. Methods: A population pharmacokinetic model using a two-compartment system was constructed using a nonlinear mixed-effects approach, incorporating 527 data points from 184 participants. External validation of the model was carried out using an additional 55 data points from 21 participants; these were not used in the construction of the model. Monte Carlo simulations were used to determine the dosage that achieved the steady state area under the curve value falling between 400 μg h/mL and 600 μg h/mL. Results: In the final model, vancomycin clearance was found to be a significant predictor of blood vancomycin levels, alongside creatinine clearance (CCr), blood urea nitrogen levels, and incidence of heart failure. CCr was calculated with adjusted body weight (AdjBW). AdjBW was selected as a predictor of the volume of distribution in the central and peripheral compartments. External validation showed that the highest proportion of cases had deviations of less than 15 % between measured and predicted values in the final model developed in this study. This indicates that our model outperforms previously developed models (five for obese patients and four for non-obese patients). Conclusions: Our model shows that determining effective vancomycin doses for overweight and obese patients depend on estimated CCr rates, AdjBW, BUN levels, and incidence of heart failure.

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Evaluating the Necessity of Two-Point Sampling for Vancomycin Area Under the Curve in Follow-up Therapeutic Drug Monitoring.

Suzuki A, Fujihara H, Yamaguchi F, Yoshida H, Tanaka H, Yagi Y, Maruyama T, Hamada Y, Ishigo T, Fujii S, Nagumo F, Samura M, Chiba H, Ebihara F, Takuma A, Komatsu T, Tomizawa A, Nishi Y, Igarashi Y, Enoki Y, Matsumoto K

Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy 31 ( 11 ) 102821 2025.09

Joint Work, ISSN 1341-321X

Objective: While both peak and trough (two-point) sampling are recommended to estimate the area under the concentration-time curve (AUC) for vancomycin, one-point sampling may reduce clinical burden. This study aimed to identify patient populations requiring two-point sampling by examining risk factors associated with AUC discrepancies between one- and two-point sampling during follow-up therapeutic drug monitoring (TDM). Method: This multicenter retrospective observational study included adult patients who received vancomycin from September 2020 to December 2023 and underwent two-point sampling at both initial and follow-up TDM. AUC was estimated using the Practical Antimicrobial TDM (PAT) version 4.0, and creatinine clearance (CLcr) was calculated using the Cockcroft-Gault equation. One- and two-point follow-up AUCs were compared using previously entered two-point concentrations from initial TDM. Patients were divided into a discrepancy group (AUC difference ≥10 %) and a non-discrepancy group. Risk factors were identified by univariate and multivariate analysis. Results: AUC values from one- and two-point sampling in 256 cases were highly correlated (r2 = 0.965, p < 0.001). Seventeen cases (6.6 %) showed discrepancies ≥10 %. Multivariate analysis identified BMI ≥25 kg/m2 (OR = 6.946, p = 0.001), CLcr <50 mL/min (OR = 5.863, p = 0.002), and ΔCLcr ≥10 mL/min (OR = 4.444, p = 0.012) as significant risk factors. Conclusion: Although one- and two-point AUCs showed strong correlation, discrepancies ≥10 % were more likely in patients with elevated BMI or impaired/unstable renal function. This suggests that two-point sampling may be essential for these patients to ensure accurate dosing of vancomycin during follow-up TDM.

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Efficacy and Safety of Isavuconazole for Invasive Fungal Infections: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Kawasaki A, Shintani R, Takao R, Nakazawa Y, Mihara T, Ikegami S, Shimada S, Matsumoto Y, Okamoto Y, Igarashi Y, Enoki Y, Taguchi K, Matsumoto K

Medical mycology 63 ( 10 ) 2025.09

Joint Work, ISSN 1369-3786

Background Isavuconazole (ISA) is a treatment option for invasive fungal infections (IFIs) and is known for a favorable safety profile compared with other antifungal agents. However, comprehensive evidence regarding its efficacy and safety remains limited. Objectives This study aimed to assess the efficacy and safety of ISA compared with other antifungal agents through a systematic review and meta-analysis restricted to randomized controlled trials (RCTs), to provide more reliable estimates of its clinical effects. Methods Following Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines, a comprehensive literature search was conducted using PubMed, the Cochrane Library, Web of Science, and ClinicalTrials.gov to identify RCTs comparing ISA with other antifungal agents. The primary outcomes were clinical response and mortality. Secondary outcomes included the incidence of adverse events, including serious, drug-related, and organ-specific toxicities. A subgroup analysis was conducted focusing on filamentous fungal infections, comparing ISA and voriconazole. Results Three RCTs met the inclusion criteria. No statistically significant differences were observed between ISA and comparator agents in terms of clinical response, mortality, or total and organ-specific adverse events. A trend toward fewer adverse events was noted in the ISA group. In the subgroup analysis, ISA and voriconazole showed similar efficacy and overall safety; however, the incidence of both drug-related adverse events and hepatobiliary disorders was significantly lower in the ISA group. Conclusions ISA demonstrated efficacy comparable to that of other antifungal agents, with a favorable safety profile in patients with IFIs, including filamentous fungal infections. This meta-analysis of RCTs provides high-quality evidence to support antifungal drug selection in clinical practice.

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Oral β-lactam combinations are effective in vitro against Mycobacterium avium, regardless of clarithromycin susceptibility.

Yoshikawa M, Nishimura T, Misawa K, Shimamura R, Suzuki K, Kashimura S, Igarashi Y, Enoki Y, Taguchi K, Hasegawa N, Namkoong H, Matsumoto K

Microbiology spectrum 13 ( 11 ) e0201225 - 15 2025.09

Joint Work

The global incidence and prevalence of pulmonary disease caused by the Mycobacterium avium complex (MAC), mainly comprising M. avium and Mycobacterium intracellulare, is increasing. However, treating MAC pulmonary disease is challenging in cases of clarithromycin (CLR)-resistant MAC or where the patients experience adverse effects or drug interactions with the few available antibiotics. Therefore, developing novel and highly effective antibiotics against MAC is crucial. Although the efficacy of dual β-lactams against Mycobacterium abscessus has been receiving attention, the efficacy of dual β-lactams against MAC remains unclear. Here, we used MAC type strains and clinical isolates to determine whether dual β-lactams were effective against MAC and which combinations synergistically inhibited bacterial growth using a broth microdilution checkerboard assay with 6 oral and 22 intravenous antibiotics. The combination effect and antibacterial activity differed between M. avium and M. intracellulare. Five combinations of oral β-lactams and 78 combinations of intravenous β-lactams showed a synergistic effect against the M. avium type strain. Among the M. avium clinical isolates, faropenem combined with cefuroxime showed the highest synergistic effect, and amoxicillin combined with tebipenem showed the lowest minimum inhibitory concentration. There was no significant difference in the combination effects between the CLR-susceptible and CLR-resistant M. avium clinical isolates in these pairs. In conclusion, regardless of CLR susceptibility, the oral β-lactam combinations were effective against M. avium. Thus, when treating MAC pulmonary disease, it is crucial to determine whether M. avium or M. intracellulare is the cause. IMPORTANCE Mycobacterium avium complex causes chronic respiratory infections, but treatment is often limited by drug resistance, intolerance, or interactions. As new therapeutic strategies are urgently needed, we focused on β-lactam antibiotics, which are widely used and well tolerated. Although dual β-lactams are effective against Mycobacterium abscessus, their utility against Mycobacterium avium complex has remained largely unexplored. Our in vitro study revealed that several β-lactam combinations are effective against Mycobacterium avium, regardless of drug resistance, indicating potential for clinical use. In contrast, Mycobacterium intracellulare showed lower susceptibility to β-lactams. Given this difference in drug susceptibility, we emphasize the clinical need to distinguish Mycobacterium avium and Mycobacterium intracellulare to optimize treatment of Mycobacterium avium complex pulmonary disease.

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Development of vancomycin population pharmacokinetic models for pediatric patients using a real-world web application database.

Oda K, Shoji K, Matsumoto K, Kawamura H, Takesue Y, Shigemi A, Kimura T

Journal of the Pediatric Infectious Diseases Society 14 ( 10 ) 2025.09

Joint Work, ISSN 2048-7193

Background: The Japanese Society of Chemotherapy developed practical area under the concentration-time curve (AUC)-guided therapeutic drug monitoring (PAT), a freely available web-based application widely used in Japan to support AUC-guided dosing of vancomycin. Its broad adoption has generated a substantial real-world pharmacokinetic database. Although PAT includes a preliminary pediatric model based on data from American children aged 3 months or older, that model requires further optimization. This study aimed to develop a population pharmacokinetic (popPK) model specifically for Japanese pediatric patients and to compare its performance with existing models. Methods: We utilized a real-world database collected through PAT between December 2022 and October 2024, comprising 1673 pediatric patients aged 3 months or older. Population pharmacokinetic analysis was performed using nonlinear mixed-effects modeling, with comparisons made against 5 existing models. Results: The developed model demonstrated strong a priori predictive performance for empirical vancomycin dosing, with a mean prediction error of 0.2 μg/mL and a mean absolute prediction error of 5.6 μg/mL. These results showed no apparent bias. Graphical diagnostics confirmed optimal a priori prediction in the developed model. A posteriori predictive performance—used for Bayesian posterior dosing—was similarly favorable across all models. Notably, 2-point sampling produced significantly different clearance estimates compared with 1-point sampling in 21 of 116 patients (18.1%). Conclusions: For Japanese pediatric patients aged 3 months or older, the developed popPK model is suitable for both empirical and Bayesian-guided vancomycin dosing. Two-point sampling improves the accuracy of clearance estimation and is recommended when feasible.

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抗微生物薬適正使用支援プログラム実践のためのガイダンス　2024年度改訂版

川口辰哉, 賀来満夫, 青木洋介, 小阪直史, 関雅文, 田邊嘉也, 藤田直久, 前田真之, 村木優一, 森田邦彦, 柳原克紀, 山田武宏, 吉田耕一郎, 二木芳人, 菅野みゆき, 菅原えりさ, 清祐麻紀子, 高橋俊司, 山本剛, 松元一明, 池田賢二, 篠原孝幸, 山岸由佳, 8学会合同抗微生物薬適正使用推進検討委員会, 公益社団法人日本化学療法学会, 一般社団法人日本感染症学会, 一般社団法人日本環境感染学会, 一般社団法人日本臨床微生物学会, 公益社団法人日本薬学会, 一般社団法人日本医療薬学会, 一般社団法人日本TDM学会, 一般社団法人日本医真菌学会

TDM研究 ((一社)日本TDM学会) 42 ( 3 ) 37 - 98 2025.09

Joint Work, ISSN 0911-1026

Prediction of treatment success in patients with Enterococcus faecium bacteremia using vancomycin AUC(24)/MIC ratio: A multicenter retrospective study.

Hanai Y, Matsumoto K, Hanawa K, Endo A, Hashi H, Miyazaki T, Yamaguchi T, Harada S, Yokoo T, Uekusa S, Yokoyama Y, Maruyama R, Tsujimura S, Asakawa D, Namiki T, Isoda R, Enoki Y, Taguchi K, Matsuo K

Diagnostic microbiology and infectious disease 113 ( 2 ) 116961 2025.06

Joint Work, ISSN 0732-8893

Background: Although vancomycin is commonly used to treat Enterococcus faecium infections, there are no clear guidelines for the optimal 24-h area under the concentration time curve to minimum inhibitory concentration (AUC<inf>24</inf>/MIC) ratio. This study aimed to determine the target AUC<inf>24</inf>/MIC ratio associated with vancomycin-treated E. faecium infection outcomes. Methods: This retrospective multicenter cohort study included adult patients who received vancomycin for ≥5 days for E. faecium-associated bloodstream infections between January 2018 and December 2023. The primary outcome was treatment success, defined as a composite of survival beyond 30 days, clinical success, and microbiological eradication. Secondary outcomes included 30-day mortality, clinical success, microbiological eradication, and nephrotoxicity. Receiver operating characteristic (ROC) curve analysis identified the AUC<inf>24</inf>/MIC cut-off value for treatment success. Multivariate regression analysis was used to determine the association between AUC<inf>24</inf>/MIC and outcomes. Results: This study included 81 patients. ROC analysis identified AUC<inf>24</inf>/MIC ≥427 as the cutoff value for treatment success. The overall treatment success rate (71.6 %) was significantly higher in the above AUC<inf>24</inf>/MIC cut-off group (81.8 %) than in the below AUC<inf>24</inf>/MIC cut-off group (59.5 %). On multivariate analysis, AUC<inf>24</inf>/MIC ≥427 was an independent predictor (adjusted odds ratio: 4.399, 95 % confidence interval: 1.203–19.320, p = 0.024) of treatment success. The clinical success and microbiological eradication rates differed significantly between the below- and above-cut-off groups, whereas nephrotoxicity rates were comparable between the groups. Conclusions: In treating E. faecium infections, vancomycin AUC<inf>24</inf>/MIC ratio ≥427 was independently associated with treatment success. However, further prospective studies are required to confirm the AUC<inf>24</inf>/MIC target.

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Risk stratification of AUC upward deviation in patients with low serum creatinine levels treated with vancomycin: a multicenter retrospective study.

Ishigo T, Suzuki A, Ibe Y, Fujii S, Fukudo M, Yoshida H, Tanaka H, Fujihara H, Yamaguchi F, Ebihara F, Maruyama T, Hamada Y, Samura M, Nagumo F, Komatsu T, Tomizawa A, Takuma A, Chiba H, Nishi Y, Enoki Y, Taguchi K, Matsumoto K

The Journal of pharmacy and pharmacology 77 ( 9 ) 1255 - 1263 2025.06

Joint Work, ISSN 0022-3573

Introduction In patients with diminished muscle mass, serum creatinine (SCr) levels may be misleadingly low, potentially leading to overestimations of kidney function and unexpectedly high blood levels of vancomycin. This study aimed to identify factors contributing to this discrepancy and develop a flowchart for stratifying the risk of excessive vancomycin exposure, measured as an upward deviation in the area under the concentration-time curve (AUC) in patients with low SCr levels. Methods We analyzed data from patients who received vancomycin and had an SCr value <0.6 mg/dL. The discrepancy between the AUC<inf>24-48 h initial dosing</inf> and AUC<inf>24-48 h TDM</inf> was calculated; a ratio (AUC<inf>24-48 h TDM</inf>/AUC<inf>24-48 h initial dosing</inf>) higher than 1.2 defined an upward deviation in the AUC. A decision tree model was constructed using classification and regression tree algorithms. Results Among the 95 patients (median age [interquartile range], 69 [58, 80] years; 68% female), the upward AUC deviation was 40% (38/95). Three factors (creatinine clearance: 115 ml/min, age: 69 years, and blood urea nitrogen/SCr: 17) were selected for the decision flowchart and included in four subgroups. Conclusion We developed a flowchart to identify patients with low SCr levels whose AUC at therapeutic drug monitoring deviated upward by >20% from the predicted AUC.

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CKD-Induced Oxidative Twitch Muscle Atrophy is Mediated by Transforming Growth Factor-β.

Homma K, Enoki Y, Taguchi K, Matsumoto K

Kidney360 6 ( 9 ) 1438 - 1447 2025.06

Joint Work

Background: Understanding the vicious cycle driving renal impairment progression and skeletal muscle atrophy in chronic kidney disease (CKD) is crucial. Therefore, this study aimed to examine the role of transforming growth factor-beta (TGF-β) in promoting skeletal muscle atrophy in CKD. Methods: A combined model of 2/3 nephrectomy and unilateral ureteral ligation, as we previously reported, was used for CKD mice. Skeletal muscle weight and changes in skeletal muscle fiber twitch type were evaluated. Using C2C12 cells, a skeletal muscle myoblast cell line, molecules that induce a reduction in type IIa muscle fibers in CKD were identified. The identified molecule, TGF-β, was administered to mice to investigate its effects on muscle fiber-type changes. Furthermore, the effects of administering a TGF-β inhibitor to CKD mice were evaluated. Results: In CKD mice, myosin heavy chain (MyHC)-specific antibody immunostaining showed an increase in atrophied MyHC IIa (oxidative twitch) muscle fibers. CKD mouse serum preferentially induces MyHC IIa fiber atrophy in C2C12 cells. TGF-β-treated mice had reduced levels of oxidative metabolic skeletal muscle and oxidative type IIa fiber, similar to CKD mice. Furthermore, TGF-β inhibitor treatment prevented the CKD-associated decrease in oxidative type IIa muscle fiber size and reduced exercise capacity. Conclusions: These findings indicate that TGF-β causes skeletal muscle deterioration in CKD by reducing oxidative metabolism and inducing type IIa fiber atrophy. In addition, our results emphasize that reversing the disrupted MyHC phenotype in CKD is a potential therapeutic target for CKD-induced muscle atrophy.

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Establishment and validation of downsized hollow-fibre infection model and pharmacokinetics/pharmacodynamics analysis of VAN on Enterococcus faecium.

Hayashi Y, Takahashi M, Sasaki M, Suzuki K, Mizukami Y, Liu X, Enoki Y, Taguchi K, Yamaguchi T, Tateda K, Matsumoto K

The Journal of antimicrobial chemotherapy 80 ( 8 ) 2092 - 2099 2025.05

Joint Work, ISSN 0305-7453

Objectives This study clarified the target values of VAN against Enterococcus faecium using pharmacokinetics/pharmacodynamics (PK/PD) analysis and compared a downsized hollow fibre infection model (HFIM) with a conventional HFIM. Methods VAN was administered subcutaneously and blood concentrations were measured to calculate the PK parameters. PD studies were performed in an infected mouse model by administering VAN at doses ranging from 25 to 400 mg/kg based on PK parameters. PK/PD parameters correlated with antimicrobial efficacy were determined, and a target value of 2 log<inf>10</inf> kills was calculated. The efficacy of VAN against E. faecium was evaluated by reproducing the VAN PK in the plasma at doses that achieved the target value using conventional and novel downsized HFIMs. Results PK/PD analysis showed that fAUC/minimum inhibitory concentration (MIC) demonstrated the most relevant index, with a target value of 249 to achieve a 2 log<inf>10</inf> kill. Blood concentrations of 750 mg VAN every 12 h (equivalent to 260 fAUC/MIC) were simulated well with both HFIMs. Changes in E. faecium caused by continuous exposure to VAN resulted in a reduction in bacterial counts by ∼6.0 log<inf>10</inf> kill 168 h after the start of treatment in both models. Downsizing reduced the extracapillary space volume, circulating medium, amount of drugs used and infectious waste. The total cost of the downsized cartridge system was approximately half that of the conventional model system. Conclusions We established a downsized HFIM and demonstrated its viability as a cost-effective and environmentally sustainable in vitro PK/PD. The findings highlighted its potential as a future PK/PD analysis standard.

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Shortening the interval between the first and the second dose of vancomycin facilitates rapid achievement of the target AUC without increasing the risk of acute kidney injury, provided the AUC on the second day is appropriately controlled: a multicenter retrospective study.

Ishigo T, Suzuki A, Ibe Y, Fujii S, Fukudo M, Yoshida H, Tanaka H, Fujihara H, Yamaguchi F, Ebihara F, Maruyama T, Hamada Y, Yagi Y, Samura M, Nagumo F, Komatsu T, Tomizawa A, Takuma A, Chiba H, Nishi Y, Enoki Y, Taguchi K, Matsumoto K

Journal of pharmaceutical health care and sciences 11 ( 1 ) 44 2025.05

Joint Work, ISSN 2055-0294

Background: The impact of shortening or extending a vancomycin dosing interval on early attainment of target blood levels and acute kidney injury (AKI) remains unclear. We investigated the relationship between the interval of the first and second doses of vancomycin and early area under the concentration-time curve (AUC) and AKI. Methods: Patients (≥ 18 years) who started vancomycin and had trough/peak blood samples were included. The definition of shortened interval as the first and second doses of vancomycin was < 12 h. The cumulative incidence of AKI within 21 days was compared using the shortened interval and AUC on day 1 and 2. Results: Among 668 patients (median age 69 [interquartile range (IQR): 57, 78] years, 40% female), the proportion achieving an AUC ≥ 400 µg·h/mL on day 1 was significantly higher in the shortened-interval group (82% vs. 50%; p < 0.001). Multivariate analysis revealed no association between a shortened interval (hazards ratio [HR], 1.10 [95% confidence interval (CI), 0.63–1.91]; p = 0.750) or an AUC > 600 µg·h/mL on day 1 alone (HR, 2.17 [95% CI, 0.64–7.42]; p = 0.220) and AKI onset. However, an AUC > 600 µg·h/mL on day 2 alone (HR, 2.92 [95% CI, 1.45–5.87]; p = 0.003) or on both days (HR, 11.18 [95% CI, 5.07–24.67]; p < 0.001) was significantly associated with increased AKI risk. Conclusions: Shortening the dosing interval facilitates early achievement of target AUC without increasing AKI risk, provided AUC on day 2 is appropriately controlled.

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Efficacy of De-Escalation to Cefmetazole in Patients with Bacteremic Urinary Tract Infections Caused by Extended-Spectrum β-Lactamase-Producing Escherichia coli

Namiki Takaya, Yokoyama Yuta, Kimura Motonori, Fukuda Shogo, Seyama Shoji, Iketani Osamu, Uwamino Yoshifumi, Jibiki Aya, Kawazoe Hitoshi, Ohtani Hisakazu, Hasegawa Naoki, Matsumoto Kazuaki, Oda Rentaro, Hashi Hideki, Suzuki Sayo, Nakamura Tomonori

Biological and Pharmaceutical Bulletin (The Pharmaceutical Society of Japan) 48 ( 5 ) 537 - 544 2025.05

Joint Work, ISSN 09186158

This study aimed to clarify the optimal value for the unbound cefmetazole concentration to remain above the minimum inhibitory concentration (MIC) (fT ≥ MIC) for efficacy of de-escalation to cefmetazole in patients with bacteremic urinary tract infection by extended-spectrum β-lactamase-producing Escherichia coli. This double-center retrospective observational study was conducted at Tokyo Bay Urayasu Ichikawa Medical Center and Keio University Hospital from January 2012 to October 2022. Efficacy was determined via clinical evaluation (mortality rate, recurrence rate, vital changes) and bacteriological evaluation, and the optimal fT ≥ MIC was calculated via receiver operating characteristic curve analysis. As a result, the number of patients evaluated were 40 (35 and 5 in the treatment success and treatment failure groups, respectively). Univariate analysis showed that fT ≥ MIC, recurrence rate, and MIC for cefmetazole against bacteria were significantly different for the two groups (p < 0.05). Receiver operating characteristic curve analysis showed that the optimal fT ≥ MIC indicating efficacy was 57% (area under the curve: 0.94, 95% confidence interval: 0.86–1.00, p = 0.002). All patients with fT ≥ MIC ≥ 57% had successful treatment, whereas the frequency of treatment failure was high among those with fT ≥ MIC <57%. The optimal fT ≥ MIC for the clinical efficacy of de-escalation to cefmetazole in patients with bacteremic urinary tract infection by extended-spectrum β-lactamase-producing E. coli was fT ≥ MIC ≥ 57%. This finding would be useful for optimal dosing of cefmetazole.

External validation of a flowchart related to achieving the target area under the concentration-time curve for vancomycin: A retrospective multicenter study

Ishigo T., Suzuki A., Ibe Y., Fujii S., Fukudo M., Yoshida H., Tanaka H., Fujihara H., Yamaguchi F., Ebihara F., Maruyama T., Yagi Y., Hamada Y., Samura M., Nagumo F., Komatsu T., Tomizawa A., Takuma A., Chiba H., Nishi Y., Igarashi Y., Enoki Y., Matsumoto K.

Journal of Infection and Chemotherapy 31 ( 5 ) 102701 2025.05

Joint Work, ISSN 1341321X

During therapeutic drug monitoring (TDM) for vancomycin (VCM), the area under the concentration-time curve (AUC) is important for balancing efficacy versus toxicity. In a previous study, we developed a decision tree (DT) model to achieve the target AUC during TDM over the follow-up period (AUCfollow-up). This study aimed to validate the DT model for achieving the target AUCfollow-up. Patients who received VCM for at least 72 h and had an initial TDM within four doses between January 2023 and December 2023 were analyzed. The AUC of the initial TDM was calculated over 2-point (peak/trough) concentrations via Bayesian estimation. The target AUCfollow-up was defined as 400–600 μg h/mL. Among 188 patients (median age [interquartile range], 66 [56, 79] years; 50 % female), the target AUCfollow-up was achieved in 70 % (132/188). When the predicted AUC was 400–600 μg h/mL, 84 % (102/121) achieved the target AUCfollow-up. In a 12 h dosing interval subgroup, 86 % (88/102) achieved the target AUCfollow-up. Conversely, when the predicted AUC was <400 or >600 μg h/mL, the proportion who achieved the target AUCfollow-up dropped to 44 % (30/67). Only 30 % (3/10) of those with creatinine clearance rates of >130 mL/min/1.73 m2 achieved the target. The area under the receiver operating characteristics curve was 0.74, and the R2 value was 0.15. Our findings confirmed the external validity of the DT model and supported its use for optimizing VCM dosing. Overall, the DT model offers a reliable framework for achieving target AUC values during follow-up for TDM, aiding safe and effective treatment.

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Methemoglobin-Encapsulating Liposome: A Low-Risk Intravascular Contrast Agent for Magnetic Resonance Imaging

Taguchi K., Sumiyoshi A., Suzuki Y., Ozawa Y., Iiyama M., Gao S., Sakai H., Osada K., Matsumoto K., Aoki I.

ACS Applied Bio Materials 8 ( 4 ) 2838 - 2846 2025.04

Joint Work

Hemoglobin shows different contrasts on magnetic resonance imaging (MRI) depending on the iron and oxygenation states of heme. Functional brain MRI utilizes the differences in the concentrations of oxyhemoglobin and deoxyhemoglobin in cerebral blood vessels; blood clots produce strong magnetic susceptibility effects. We hypothesized that methemoglobin (MetHb)-based nanoparticles can act as MRI contrast agents because MetHb levels in red blood cells affect relaxivity and are strictly regulated to <1% in the blood. Herein, we describe the synthesis of methemoglobin-encapsulated liposomes (Met-HbVs) as contrast agents for MRI. Met-HbV, with a size of approximately 200 nm, increased longitudinal relaxivity (r1) by 2.44-fold compared with hemoglobin-encapsulated liposomes in vitro. In contrast, the transverse relaxation capacity (r2) of Met-HbVs was similar to that of the hemoglobin-encapsulated liposomes. Owing to its relaxivity, Met-HbV enhanced the signal intensity on T1-weighted images and angiography, especially in the veins. Furthermore, deleterious biological responses were seldom observed after Met-HbV administration in mice with chronic renal failure. In conclusion, Met-HbV possesses potential as a vascular contrast agent in MRI for angiography, with advantages over gadolinium-based contrast agents in terms of safety for patients with renal failure. To the best of our knowledge, this is the first report demonstrating the potential of MetHb as a biomaterial for contrast agents in MRI.

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Influence factors of metronidazole-related CNS disorders: an analysis of the Japan adverse drug event report and FDA adverse event reporting system.

Takada K, Enoki Y, Samura M, Igarashi Y, Taguchi K, Tanikawa K, Matsumoto K

Expert opinion on drug safety 1 - 7 2025.04

Joint Work, ISSN 1474-0338

Background: Metronidazole (MNZ) can be administered for various infections. The impact of comorbidities/concomitant drugs on MNZ-induced central nervous system (CNS) disorders remains unclear. Research design and methods: We assessed the risk of metronidazole-related CNS disorders using the Japan Adverse Drug Event Report (JADER, May 2023) and the US Food and Drug Administration Adverse Event Reporting System (FAERS, Q1 2023), excluding comorbidities/concomitant drugs. Clonazepam and diazepam were evaluated as potential prophylactics based on the efficacy of benzodiazepines for MNZ-related CNS disorders. Reporting odds ratios (ROR) and 95% confidence intervals (CI) were calculated. Additionally, sensitivity analysis by sex and age was conducted. Results: The ROR (95% CI) of CNS disorders associated with MNZ in JADER and FAERS were 3.16 (2.69–3.72) and 1.69 (1.64–1.73), respectively. MNZ was significantly related to CNS disorders after excluding comorbidities (brain/spinal cord or liver abscesses) and concomitant drugs (glucocorticoids, antiepileptic, antiparkinson, and schizophrenia drugs). In sensitivity analysis, MNZ was significantly related to CNS disorders, despite sex and age. The ROR in the concomitant with clonazepam (CZP) was 0.70 (0.53–0.92) in FAERS. Conclusion: MNZ may be associated with CNS disorders, even if comorbidities/concomitant drugs that are potential risk factors for CNS disorders are excluded. Additionally, CZP may suppress CNS disorders.

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Pharmacists’ Awareness and Support for Common-use Pharmaceuticals: A Survey Study

Okamoto Yuko, Taguchi Kazuaki, Enoki Yuki, Hori Satoko, Yamaura Katsunori, Matsumoto Kazuaki

Iryo Yakugaku (Japanese Journal of Pharmaceutical Health Care and Sciences) (Japanese Society of Pharmaceutical Health Care and Sciences) 51 ( 4 ) 196 - 202 2025.04

Joint Work, ISSN 1346-342X

The Japan Pharmaceutical Association proposed a new category of over-the-counter (OTC) drugs, tentatively termed “common-use pharmaceuticals for both medical and general use,” in their “Policy Proposal 2022.” This new category will be classified as “Class 0,” meaning the risk classification will remain unchanged. Consequently, pharmacists will be responsible for providing information and selling these products. Understanding pharmacists’ perceptions of this policy proposal is crucial for developing a framework for this new category; however, no relevant evidence exists. Therefore, this study conducted a web-based, anonymous, self-administered questionnaire survey targeting pharmacists in hospitals, health insurance pharmacies, and drugstores to investigate their awareness and views on the proposal. The results revealed that less than 30％ of the pharmacists, regardless of their job role (hospital, health insurance pharmacy, or drugstore), were aware of the proposal, indicating a low level of awareness. However, regardless of their awareness at the time of the survey, more than half of the respondents expressed support for establishing these common-use pharmaceuticals, with few opposing the idea. Many pharmacists identified cold remedies, antitussives/expectorants, antipyretic analgesics, digestive medications, topical medications (eg, patches), and allergy medications as medical drugs that should be classified under the new category. This study is the first to offer insight into pharmacist awareness and views regarding the establishment of common-use pharmaceuticals, providing evidence for future discussions.

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