In-Hwan Baek

Background Humidifier disinfectants (HDs) were used as household biocidal products to prevent microbial growth in humidifiers and were withdrawn from the South Korean market in 2011 following recognition of associated health risks. Although epidemiological studies have reported associations between HD exposure and various respiratory diseases, the overall strength of evidence and exposure–response relationships have not been comprehensively quantified. Objective This study aimed to systematically review and quantitatively synthesize observational studies to evaluate the association between HD exposure and respiratory diseases and to assess exposure–response relationships across multiple exposure metrics. Methods PubMed, Excerpta Medica Database, and the Cumulative Index to Nursing and Allied Health Literature were searched through September 19, 2025. The primary outcome was the pooled odds ratio (OR) for respiratory disease risk among exposed versus non-exposed individuals. Secondary outcomes assessed exposure–response relationships using categorical and continuous exposure metrics. Results Seventeen observational studies conducted in South Korea were included. HD exposure was associated with a markedly increased risk of respiratory diseases (pooled OR 7.02, 95% CI 1.97–24.98), with the strongest association observed for lung injury (pooled OR 94.53, 95% CI 61.31–145.73). Age-stratified subgroup analyses exhibited significantly elevated risks across adult, pediatric, and mixed-age populations. Exposure–response analyses demonstrated significant associations across multiple categorical exposure metrics, including usage duration, daily usage hours, cumulative use hours, airborne concentration, cumulative exposure level, longer use during sleep, and HD use during sleep. Continuous exposure analyses indicated that affected individuals had significantly longer cumulative use hours than unaffected individuals (pooled standardized mean difference 0.197, 95% CI 0.069–0.325). Significance This study provides quantitative evidence supporting strong associations between HD exposure and respiratory diseases and demonstrates consistent exposure–response relationships across multiple exposure metrics, supporting a causal relationship between inhalational exposure to HDs and adverse respiratory outcomes. Impact statement This study provides comprehensive quantitative evidence that humidifier disinfectant exposure is strongly associated with respiratory diseases and demonstrates consistent exposure–response relationships across multiple exposure metrics. These findings strengthen causal inference for inhalational toxicity of humidifier disinfectants and highlight the importance of exposure assessment in environmental health risk evaluation. The results provide important evidence for environmental health policy, risk assessment, and prevention strategies for inhalation exposure to household biocidal products.

Background Topical anticholinergic agents are non-invasive treatment options for primary axillary hyperhidrosis (PAH). Sofpironium bromide was recently approved by the US Food and Drug Administration (FDA). A comprehensive evaluation of the efficacy and safety of available topical anticholinergics may inform clinical practice. Objectives To assess the efficacy and safety of topical anticholinergic therapies for PAH through systematic review and meta-analysis of randomized controlled trials (RCTs). Methods Five databases were searched on September 9, 2024. Primary outcomes included a ≥2-point improvement in the Hyperhidrosis Disease Severity Scale (HDSS) and ≥50% reduction in gravimetric sweat production (GSP). Secondary outcomes included subjective symptom improvement and objective sweat reduction. Safety outcomes included treatment-emergent adverse events (TEAEs), anticholinergic-related adverse events, and local application site reactions. The review protocol was registered in PROSPERO (CRD42024583376). Results Eight RCTs (n = 1921) that evaluated glycopyrronium, sofpironium bromide, and umeclidinium were included. Topical agents significantly outperformed placebos for HDSS ≥2-point improvement (risk ratio [RR]: 2.40; 95% confidence interval [CI]: 2.01–2.86) and GSP ≥50% reduction (RR: 1.43; 95% CI: 1.21–1.70). Sofpironium was the most effective HDSS treatment, whereas glycopyrronium showed highest efficacy against GSP. Topical agents were associated with increased risk of TEAEs (RR: 1.43; 95% CI: 1.14–1.79), with sofpironium associated with highest risk of dry mouth and glycopyrronium with highest risks for mydriasis and constipation. Conclusions Topical anticholinergic agents are effective for PAH treatment, with distinct efficacy and safety profiles. Although the available evidence is limited by the small number of trials, short follow-up durations, and heterogeneity in outcome reporting, these findings support the role of topical anticholinergic therapy as an effective non-invasive option for PAH.

Bepotastine has a short half-life of approximately 2 hours and its absorption is limited to the upper small intestine. These characteristics present a significant challenge for the development of a once-daily sustained-release formulation, as a gastro-retentive system capable of prolonging gastric residence time in the upper absorption window is required. In this study, a low-density gastro-retentive tablet was developed to achieve immediate floating without a lag time. This floating behavior was achieved by controlling the apparent density of the tablets and incorporating the porous characteristics of magnesium aluminometasilicate. The sustained floating over 4 hours in vitro was attributed to air entrapment resulting from gel layer formation by the tablet matrix. Furthermore, drug release was confirmed to be primarily governed by matrix erosion rather than diffusion. Pharmacokinetic evaluation in beagle dogs demonstrated that the gastro-retentive tablet achieved a systemic exposure of 95.7% relative to the reference formulation, whereas conventional sustained-release formulations without gastric retention achieved only 64.5–88.6%. Subsequent PBPK model simulation confirmed that the in vitro characteristics of the gastro-retentive tablet were also manifested in vivo. The gastric residence time of approximately 180 minutes, as estimated by PBPK modeling, supported the relevance of the in vitro floating behavior to in vivo gastric retention. These results suggest that the proposed gastro-retentive tablet represents a practical sustained-release strategy to overcome the bioavailability reduction caused by limited gastric transit time for drugs with a narrow absorption window.

Background/Objectives: MHY498, a tyrosinase inhibitor, exhibits poor water solubility, which limits its topical delivery. Despite the importance of solubility data in rational formulation design, comprehensive information on its solubility behavior in various solvents and across a range of temperatures remains limited. Thus, this study aimed to systematically evaluate the solubility characteristics of MHY498 and to develop a nanosuspension formulation using an antisolvent precipitation approach to facilitate the development of an optimized topical formulation. Methods: In this study, we measured the solubility of MHY498 in various monosolvents and diethylene glycol monoethyl ether (DEGME) + water solvent mixtures at 293.15–313.15 K using a solid–liquid equilibrium technique. Based on these solubility data, MHY498 nanosuspensions were prepared via antisolvent precipitation guided by a Box–Behnken design matrix. In vitro skin permeability was also assessed using a Franz diffusion cell system to assess the topical delivery potential of the MHY498 nanosuspensions. Results: Among the investigated monosolvents, MHY498 exhibited the highest solubility in dimethylformamide, dimethylacetamide, DEGME, while the lowest solubility was observed in water. The solubility increased with temperature and DEGME content in solvent mixtures, and the experimental data were well described by thermodynamic and semi-empirical models, indicating an endothermic and spontaneous dissolution process. Solvent–solute interaction analysis revealed that hydrogen-bonding and nonspecific polarity interactions played key roles in enhancing MHY498 solubility. All nanosuspensions prepared within the design space exhibited particle sizes below 150 nm, and the optimized formulation achieved an average particle size of 28.1 nm. The optimized nanosuspension demonstrated a 3.3-fold increase in the cumulative permeated amounts compared with the conventional microsuspension. Conclusions: These findings demonstrate that a rational solvent selection strategy based on thermodynamic solubility analysis and antisolvent precipitation enables effective nanosuspension formulation of MHY498. The DEGME–water system was identified as a formulation-relevant solvent environment that supports both adequate drug solubilization and reproducible formation of nanosized particles. The resulting nanosuspension exhibited favorable particle size characteristics and enhanced formulation feasibility for topical applications. Therefore, it was shown that the developed nanosuspension system, established through a solubility-driven systematic approach, represents a promising strategy for improving topical delivery of MHY498.

Background and Objective Fixed-dose combinations (FDCs) of amlodipine and telmisartan are widely used for hypertension management owing to their efficacy and improved adherence. This study aimed to characterize the pharmacokinetics (PKs) of both drugs after a single oral dose of a single-pill FDC of amlodipine 5 mg/telmisartan 80 mg in healthy Korean males. Methods A total of 681 amlodipine and 1500 telmisartan plasma concentrations from 32 healthy Korean males were retrospectively obtained from a bioequivalence study. Noncompartmental analysis and population analysis were conducted using WinNonLin™ (Pharsight Corp., Mountain View, CA, USA) and NONMEM^® (ICON Development Solutions, Hanover, MD, USA), respectively. A two-compartment model with first-order absorption and elimination was selected for both drugs. Covariate screening using a stepwise approach evaluated 38 demographic and clinical factors. Results Amlodipine exhibited a longer half-life and a larger apparent volume of distribution than telmisartan. Telmisartan PKs showed high interindividual (45.9% for absorption rate constant, 45.3% for apparent volume of distribution of the central compartment [V₁/F], and 40.9% for apparent clearance [CL/F]), interoccasion (53.7% for V₁/F), and residual (80.3%) variabilities. Preliminary covariate analysis suggested that body surface area and age potentially influenced V₁/F and CL/F for amlodipine, while height, smoking status, and total bilirubin levels were associated with telmisartan V₁/F and CL/F. Conclusions To our knowledge, this is the first population PK study to characterize the PKs of amlodipine and telmisartan co-administered as a single-pill FDC and to identify preliminary covariates that may influence their PK profiles.

In this study, we evaluated the antioxidant activities of esculetin and four synthesized derivatives (E1, 2-oxo-2H-1-benzopyran-6,7-diyl diacetate; E2, 7-hydroxy-2-oxo-2H-1-benzopyran-6-yl acetate; E3, 7-(methoxymethoxy)-2-oxo-2H-1-benzopyran-6-yl acetate; E4, 7-hydroxy-2-oxo-2H-1-benzopyran-6-yl 2,4-dinitrobenzene-1-sulfonate) against oxidative stress in hepatocytes. In HepG2 cells, treatment with 1 mM tert-butyl hydroperoxide (TBHP) reduced cell viability to 40%, while co-treatment with esculetin restored cell viability. Among the esculetin derivatives, E2 exhibited the most significant cytoprotective effect, while E4 showed the lowest. Furthermore, E2 at 25 µM concentration showed the similar effects to esculetin in reducing ROS generation and preventing glutathione depletion. The treatment of E2 also enhanced the expression of HO-1 and GCLC proteins against oxidative stress. On the other hand, TBHP-induced oxidative stress decreased antioxidant activities including glutathione reductase, glutathione peroxidase, and catalase; however, E2 significantly increased these antioxidant activities. These findings suggest that the esculetin derivative, particularly E2, possesses potential as an antioxidant aimed at enhancing physiological functions.

Background and Objective Telmisartan exhibits significant pharmacokinetic (PK) variability, but it remains unclear whether its PK profile is altered in hypertensive patients. This study aimed to characterize telmisartan PKs by conducting a meta-analysis and developing a pooled population PK model based on data from healthy subjects and hypertensive patients. Methods Relevant literature was identified by a systematic approach. Eighteen studies were selected for analysis, which included 394 healthy subjects receiving single doses of telmisartan, 190 healthy subjects receiving repeated doses, along with 295 hypertensive patients receiving repeated doses. Pooled population PK analysis incorporated 20 mean concentration-time profiles from 14 studies. Meta-analyses were performed using OpenMeta-Analyst, and population PK modeling was performed using NONMEM^®. Results Repeated telmisartan doses increased peak plasma concentrations. However, other noncompartmental PK parameters remained consistent across healthy and hypertensive populations. Telmisartan PKs were best described using a two-compartment model with first-order absorption and elimination in pooled analysis. Typical PK parameter values for apparent clearance (CL/F), apparent central and peripheral volumes of distribution (V₁/F and V₂/F), absorption rate constant (k_a), and absorption lag time were 18.3 L/h, 20.7 L, 360 L, 0.183 h⁻¹ and 0.228 h, respectively. Interindividual variabilities in CL/F, V₁/F, and k_a were 84%, 122%, and 106%, respectively. Covariate analysis revealed significantly lower CL/F (63.7%) and V₁/F (90.3%) values in hypertensive patients than healthy subjects. Conclusion These findings quantified the variability of telmisartan PK profile and highlighted the differences between healthy individuals and hypertensive patients, suggesting the need for optimized dosage strategies to improve therapeutic outcomes.

Background/Objectives: This study investigates the impact of supercritical antisolvent (SAS) process parameters on the particle formation of telmisartan, a poorly water-soluble drug. Methods: A fractional factorial design was employed to examine the influence of the SAS process parameters, including solvent ratio, drug solution concentration, temperature, pressure, injection rate of drug solution, and CO₂ flow rate, on particle formation. Solid-state characterizations of the SAS process particles using XRD and FT-IR confirmed their amorphous nature. The effect of particle size on the kinetic solubility, dissolution, and oral bioavailability of telmisartan was also assessed. Results: Using a mixture of dichloromethane and methanol, telmisartan amorphous nano-microparticles with sizes between 200 and 2000 nm were produced. The key parameters, particularly drug solution concentration and temperature, significantly affected the particle size. Interestingly, the ratio of the solvent mixture also had a significant effect on the particle morphology. Further experiments were performed to determine the conditions for preparing telmisartan amorphous nano-microparticles with various sizes by controlling the solvent mixture ratio and the concentration of the drug solution. It was revealed that a reduction in the amorphous particle size enhanced both the kinetic solubility and dissolution rates, leading to a significantly increased in vivo oral bioavailability in rats compared to unprocessed telmisartan. Conclusions: These findings suggest that SAS processing, utilizing adjustments of process parameters, offers an effective strategy for enhancing the bioavailability of poorly soluble drugs by generating amorphous spherical nano-microparticles with optimized particle size.

Phthalates are ubiquitous in diverse environments and have been linked to a myriad of detrimental health outcomes. However, the association between phthalate exposure and allergic rhinitis (AR) remains unclear. To address this knowledge gap, we conducted a systematic review and meta‐analysis to comprehensively evaluate the relationship between phthalate exposure and childhood AR risk. We searched the Cumulative Index to Nursing and Allied Health Literature, Excerpta Medica Database, and PubMed to collect relevant studies and estimated pooled odds ratios (OR) and 95% confidence intervals (CI) for risk estimation. Ultimately, 18 articles, including seven cross‐sectional, seven case–control, and four prospective cohort studies, were selected for our systematic review and meta‐analysis. Our pooled data revealed a significant association between di‐2‐ethylhexyl phthalate (DEHP) exposure in children's urine and AR risk (OR = 1.188; 95% CI = 1.016–1.389). Additionally, prenatal exposure to combined phthalates and their metabolites in maternal urine was significantly associated with the risk of childhood AR (OR = 1.041; 95% CI = 1.003–1.081), although specific types of phthalates and their metabolites were not significant. Furthermore, we examined environmental phthalate exposure in household dust and found no significant association with AR risk (OR = 1.021; 95% CI = 0.980–1.065). Our findings underscore the potential hazardous effects of phthalates on childhood AR and offer valuable insights into its pathogenesis and prevention.

Fibroblast growth factor (FGF)‐21 analogs are potential therapeutic candidates for metabolic dysfunction‐associated steatohepatitis (MASH). This systematic review and meta‐analysis aimed to assess the efficacy and safety of the FGF‐21 analogs, efruxifermin, pegbelfermin, and pegozafermin for MASH treatment. A comprehensive systematic review and meta‐analysis of randomized controlled trials from five major databases was conducted. Primary efficacy outcomes focused on liver histological improvement, while secondary efficacy outcomes encompassed reductions in liver fat content and improvements in biochemical parameters. Safety outcomes examined included treatment‐emergent adverse events (TEAEs), treatment‐related TEAEs, TEAEs leading to discontinuation, and serious TEAEs. Eight eligible studies involving 963 patients were included in this review. Compared with the placebo group, the FGF‐21 analog‐treated group exhibited significantly improved primary efficacy outcomes, specifically ≥1 stage improvement in fibrosis with no worsening of MASH (risk ratio [RR] = 1.83; 95% confidence interval [CI] = 1.27–2.62) and at least two‐point improvement in the non‐alcoholic fatty liver disease activity score with no worsening of fibrosis (RR = 2.85; 95% CI = 2.06–3.95). Despite an increased risk of TEAEs (RR = 1.17; 95% CI = 1.08–1.27) and treatment‐related adverse events (RR = 1.75; 95% CI = 1.40–2.19), FGF‐21 analogs exhibited an acceptable safety profile. FGF‐21 analogs were significantly better in achieving liver histological improvements and beneficial biochemical outcomes compared with placebo, with a tolerable safety pattern. These findings shed light on the efficacy and safety of FGF‐21 analogs and provide valuable evidence for their application as MASH therapeutics.