Eun-Seok Park

Sungkyunkwan University, Sŏul, Seoul, South Korea

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Publications (80)188.91 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Liquid crystal (LC) technology has attracted much interest for new injectable sustained-release (SR) formulations. In this study, an injectable liquid crystal-forming system (LCFS) including entecavir was prepared for the treatment of hepatitis B. In particular, an anchoring effect was introduced because LCFSs are relatively hydrophobic while entecavir is a slightly charged drug. The physicochemical properties of LCFSs were investigated by cryo-transmission electron microscopy (cryo-TEM), polarized optical microscopy, and small-angle X-ray scattering (SAXS), showing typical characteristics of the liquid crystalline phase, which was classified as the hexagonal phase. A pharmacokinetic study in rats showed sustained release of entecavir for 3-5 days with a basic LCFS formulation composed of sorbitan monooleate (SMO), phosphatidyl choline (PC), and tocopherol acetate (TA) as the main LC components. 1,2-dipalmitoyl-sn-glycero-3-phosphatidic acid (DPPA), an anionic phospholipid, was added to increase the anchoring effect between the cationic entecavir and the anionic DPPA, which resulted in a 1.5-times increase in half-life in rats. In addition, anchoring was strengthened by optimizing the pH to 2.5-4.5, increasing the half-life in the rat and dog. Also, due to the increasing terminal half-life from rat to dog resulting from species differences, LCFS produced one week delivery of entecavir in rat and two weeks delivery in dog. Therefore, LCFS injection using the anchoring effect for entecavir can potentially be used to deliver the drug over more than 2 weeks or even 1 month for the treatment of hepatitis B. Copyright © 2015. Published by Elsevier B.V.
    International Journal of Pharmaceutics 05/2015; 490(1-2). DOI:10.1016/j.ijpharm.2015.05.049 · 3.65 Impact Factor
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    ABSTRACT: The main objective of this study was to develop novel orally administrable tablets containing solid dispersion granules (SDG) of amorphous paclitaxel (PTX) prepared by fluid bed technology, and to evaluate its in vitro dissolution and in vivo pharmacokinetics (PK) in beagle dogs. The SDG were prepared using optimized composition by fluid bed technology, and characterized for solid-state properties. The release study of SDG tablet (SDG-T) in simulated gastric fluid showed a rapid release of PTX, reaching maximum dissolution within 20 min. Finally, the PK profile of SDG-T and a reference formulation Oraxol™ (oral solution formulation used in Phase I clinical study) at a dose of 60 mg orally with co-administration of P-gp inhibitor HM38101, and Taxol® at a dose of 10 mg intravenously (i.v.) was investigated in beagle dogs. The mean absolute BA% of PTX following SDG-T and Oraxol™ solution was 8.23 and 6.22% in comparison to i.v. administration of Taxol®. The relative BA% of PTX from SDG-T in comparison to Oraxol™ solution was 132.25% at a dose of 60 mg following oral administration. In conclusion, we have successfully prepared PTX tablets with solid dispersion granules (SDG) of amorphous PTX using fluid bed technology that could provide plasma PTX concentration in the range of 10-150 ng/mL for a period of 24 h following oral administration in dogs with a P-gp inhibitor. Hence, this could be a promising formulation for PTX oral delivery and could be used in our intended clinical studies following pre-clinical efficacy studies.
    Drug Development and Industrial Pharmacy 03/2015; DOI:10.3109/03639045.2015.1018275 · 2.10 Impact Factor
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    ABSTRACT: The aim of present study was to design oxycodone once-a-day controlled-release (CR) tablets and to perform in vitro/in vivo characterizations. Release profiles to achieve desired plasma concentration versus time curves were established by using simulation software and reported pharmacokinetic parameters of the drug. Hydroxypropyl methylcellulose (HPMC) 100,000 mPa·s was used as a release modifier because the polymer was found to be resistant to changes in conditions of the release study, including rotation speed of paddle and ion strength. The burst release of the drug from the CR tablets could be suppressed by applying an additional HPMC layer as a physical barrier. Finally, the oxycodone once-a-day tablet was comprised of two layers, an inert HPMC layer and a CR layer containing drug and HPMC. Commercial products, either 10 mg bis in die (bid [twice a day]) or once-a-day CR tablets (20 mg) were administered to healthy volunteers, and calculated pharmacokinetic parameters indicated bioequivalence of the two different treatments. The findings of the present study emphasize the potential of oxycodone once-a-day CR tablets for improved patient compliance, safety, and efficacy, which could help researchers to develop new CR dosage forms of oxycodone.
    Drug Design, Development and Therapy 01/2015; 9:695. DOI:10.2147/DDDT.S77356 · 3.03 Impact Factor
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    ABSTRACT: This paper focuses on the development and physicochemical characterization of a self-microemulsifying drug delivery system (SMEDDS) containing a fixed-dose combination of atorvastatin (ATR) and ezetimibe (EZT). The solubility of both drugs was determined in excipient screening studies. Ternary-phase diagrams were drawn for 27 systems composed of different surfactants, cosurfactants, and oils at different surfactant-to-cosurfactant (S/CoS) ratios, and the system exhibiting the largest percentage area of the self-microemulsifying region was selected. The optimum oil ratio in the SMEDDS was selected by evaluating the mean droplet size of the resultant microemulsions. The underlying mechanism of the lower ATR loading capacity compared with EZT was elucidated by measurement of the zeta potential and UV absorption analysis. The results implied that ATR was located exclusively in the surfactant-cosurfactant layer, whereas EZT was located both in the microemulsion core and the surfactant-cosurfactant layer. In vitro dissolution studies showed that the SMEDDS had higher initial dissolution rates for both drugs when compared with marketed products. More importantly, EZT had a significantly increased dissolution profile in distilled water and pH 4.0 acetate buffer, implying enhanced bioavailability.
    Chemical & pharmaceutical bulletin 01/2015; 63(6):423-30. DOI:10.1248/cpb.c14-00814 · 1.38 Impact Factor
  • IET Microwaves Antennas & Propagation 09/2014; 8(12):912-920. DOI:10.1049/iet-map.2013.0387 · 0.97 Impact Factor
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    ABSTRACT: The aim of this study was to design and evaluate extended-release formulations of a model drug, nicorandil, in order to achieve the desired steady-state plasma concentration of drug in vivo. Simulation was employed to estimate optimum dissolution and absorption rate of nicorandil. The dissolution test was employed using pH 1.2, 4.0, 6.8 buffer solution, or water, to measure the in vitro release behaviors of nicorandil formulations. A single dose (15 mg) of each formulation was orally administered to four beagle dogs under fasted conditions, and the pharmacokinetic parameters were calculated. The in vitro/in vivo relationship of the extended-release formulation was confirmed using in vitro dissolution profiles and plasma concentrations of drug in beagle dogs. Nicorandil was released completely within 30 min from the immediate-release tablets and released for 24 hr from the extended-release tablets. The nicorandil plasma concentration could be modified by adjusting the drug release rate from the extended-release formulation. The release rate of nicorandil was the rate-limiting step in the overall absorption of drug from the extended-release formulations. These results highlight the potential of a nicorandil extended-release formulation in the treatment of angina pectoris.
    Asian Journal of Pharmaceutical Sciences 09/2014; 10(2). DOI:10.1016/j.ajps.2014.09.003
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    ABSTRACT: In the present study, controlled-release microparticles for orally disintegrating tablets (ODT) were prepared using two different processes, spray drying and fluidized bed coating processes. Pramipexole dihydrochloride monohydrate (PRM), an anti-Parkinson's disease agent, was selected as a model drug. The in vitro release rate and morphology of microparticles were evaluated and compared. The size of microparticles prepared by spray drying (SD microparticles) and fluidized bed coating (FC microparticles) was around 10 and 200 µm, respectively. The latter size was defined by the size of an inert core bead. The release behavior of SD microparticles was characterized by a large initial burst release prior to slow release. In the case of FC microparticles, the initial burst release was smaller than that of SD microparticles and the compression process damaged the release-controlling layer, which led to a change in release rate. The results indicated the importance of carefully considering the manufacturing process for microparticles during the design of controlled-release ODT.
    Drying Technology 05/2014; 32(8):935-945. DOI:10.1080/07373937.2013.875562 · 1.77 Impact Factor
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    ABSTRACT: An injectable liquid crystal-forming system (LCFS) was prepared by using sorbitan monooleate (SMO) as a new liquid crystal-forming material for injections, and its potential use of clinically available sustained-release formulation was evaluated. LCFS was prepared using SMO mixed with phosphatidyl choline and tocopherol acetate, and contained 3.75mg of leuprolide acetate as a monthly dose in 90μl of a liquid form. The semi-solid mesophase was formed from the liquid LCFS when it contacted water. The mesophase showed typical characteristics of the liquid crystalline phase, which was classified as the hexagonal phase. The safety of the LCFS was studied by an in vitro extraction colony assay and by examining the injection site in rats and white rabbits after an autopsy. Both in vitro release test and in vivo pharmacokinetic and pharmacodynamic studies showed a sustained release of leuprolide. When compared with a commercial depot formulation of leuprolide, the LCFS showed a similar AUClast value and significantly reduced initial burst with the sufficient suppression of testosterone after subcutaneous injections in rats and dogs. The LCFS can serve as a new type of sustained-release injection formulations for its safety, ease of preparation, and sustained release properties.
    Journal of Controlled Release 04/2014; 185(1). DOI:10.1016/j.jconrel.2014.04.034 · 7.26 Impact Factor
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    ABSTRACT: The objective of this study was to evaluate the healing effects of a chitosan-based, film-forming gel containing tyrothricin (TYR) in various rat wound models, including burn, abrasion, incision, and excision models. After solidification, the chitosan film layer successfully covered and protected a variety of wounds. Wound size was measured at predetermined timepoints after wound induction, and the effects of the film-forming gel were compared with negative (no treatment) and positive control groups (commercially available sodium fusidate ointment and TYR gel). In burn, abrasion and excision wound models, the film-forming gel enabled significantly better healing from 1 to 6 days after wound induction, compared with the negative control. Importantly, the film-forming gel also enabled significantly better healing compared with the positive control treatments. In the incision wound model, the breaking strength of wound strips from the group treated with the film-forming gel was significantly increased compared with both the negative and positive control groups. Histological studies revealed advanced granulation tissue formation and epithelialization in wounds treated with the film-forming gel. We hypothesize that the superior healing effects of the film-forming gel are due to wound occlusion, conferred by the chitosan film. Our data suggest that this film-forming gel may be useful in treating various wounds, including burn, abrasion, incision and excision wounds.
    Archives of Pharmacal Research 04/2014; 38(2). DOI:10.1007/s12272-014-0368-7 · 1.75 Impact Factor
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    ABSTRACT: The aim of the present study was to prepare the particulate taste-masking system to mask the bitter taste of sildenafil citrate (SC), a well-known phosphodiesterase-5 inhibitor used for erectile dysfunction (ED) and pulmonary artery hypertension (PAH). It was evaluated for the taste masking efficiency by the in vitro measurement using electronic tongue (e-tongue) system and the in vivo human panel sensory test. Microcapsules were prepared by microencapsulation with a gastro-soluble polymer, Eudragit(®) E100 (E100), using a spray drying technique at four different weight ratios (2:1, 1:1, 1:2, and 1:3). Characters of prepared microcapsules and the effect of polymer ratio on the taste masking were investigated. The particle morphology and the distribution of SC in microcapsules were observed by SEM-EDS and physical properties were evaluated by PXRD, Raman spectroscopy, and DSC. By drug dissolution studies at pH 1.2 buffer and DW, it was found that E100 was not able to alter the drug release at stomach. As the result of taste evaluation studies, there were a good correlation (R(2)=0.9867) between the weight ratio of polymer and the taste masking efficiency expressed in the distances on the PCA map of the e-tongue data, and a relevance of the e-tongue measurement with the result of sensory test.
    International Journal of Pharmaceutics 03/2014; 466(1-2). DOI:10.1016/j.ijpharm.2014.03.001 · 3.65 Impact Factor
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    ABSTRACT: Homosalate (HMS) is an ultraviolet (UV) filtering agent used in sunscreens and other cosmetics for skin protection purposes. Despite the widespread use of these products, absorption, disposition, and in vivo endocrine disrupting potential of HMS have not been characterized. Thus, the aim of this study was to examine the percutaneous absorption, disposition, and exposure assessment of HMS in rats. Initially, sunscreen preparations of petrolatum jelly, oily solution, lotion, and gel were prepared and evaluated for in vitro permeation of HMS across excised rat skin. Dermal permeability was greatest for gel, and this preparation was used in subsequent in vivo topical application investigations. After iv injection (0.5, 2, or 5 mg/kg), the pharmacokinetics of HMS was linear and was characterized by a large Vd ss (13.2-17 L/kg), high Cls (4.5-6.1 L/h/kg), and long t1/2 (6.1-8.4 h). After topical application of gel, the bioavailability of HMS was 5.4 ± 1.1 and 4.2 ± 0.6% for high and low doses (10 and 20 mg), respectively. Consistent with the prolonged absorption (T max 11.2 ± 1.8 and 12 ± 0 h for low and high doses, respectively), the terminal t 1/2 was longer after topical application (23.6-26.1 h) compared to iv injection. A population pharmacokinetic model was further developed to simultaneously fit the time courses of plasma concentrations and dermal content data after iv injection and topical application. Findings of this study may be useful to further examine the relationship between exposure and endocrine disrupting potential of HMS in risk assessment.
    Journal of Toxicology and Environmental Health Part A 02/2014; 77(4):202-13. DOI:10.1080/15287394.2013.861376 · 1.83 Impact Factor
  • Journal of Controlled Release 01/2014; 185:62–70. · 7.26 Impact Factor
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    ABSTRACT: The aims of the present study were to prepare hydroxypropylmethyl cellulose-based matrix tablets prepared using the freeze-drying method for gastroretentive delivery of ecabet sodium (ECS), a locally acting antigastric ulcer drug, and to perform in vitro/in vivo characterizations. The freeze-dried gastroretentive tablets (FD-GRTs) had porous structures, while they had good friability as a pharmaceutical dosage form. The porous structures lowered the tablet density, allowing the tablet to float without any lag time. Buoyancy of FD-GRT was maintained until they were entirely disintegrated during an in vitro release study. Release rate of ECS could be controlled by the amount of ethylcellulose (EC) in FD-GRT. As amount of EC in the composition was increased, there was a decrease in both release rate and erosion rate of FD-GRT. When administered to a miniature pig, FD-GRT remained in the stomach for more than 12 h, which was significantly longer than a conventional sustained release tablet. The new FD-GRT do not contain any excipients for buoyancy and do not require any lag time for buoyancy, consequently it could be considered to be safer and more effective than conventional floating-type GRT. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:262–273, 2014
    Journal of Pharmaceutical Sciences 01/2014; 103(1). DOI:10.1002/jps.23798 · 3.01 Impact Factor
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    ABSTRACT: The aims of the present study were to prepare hydroxypropylmethyl cellulose (HPMC)-based porous matrix tablets for gastroretentive drug delivery and to characterize their physicochemical properties. Gabapentin (GBP) was used as a model drug. Paste containing GBP, HPMC and water was molded and freeze-dried to prepare freeze-dried gastroretentive matrix tablet (FD-GRT). In vitro drug release and erosion studies were also performed. Although FD-GRT exhibited porous structure, they had good tablet strength and friability. Density of FD-GRT ranged from 0.402 to 0.509 g/cm3 and thus they could float on the medium surface without any lag time. FD-GRT was remained floated until the entire matrix erosion or end of drug release during in vitro release test. Release behavior of GBP could be modulated by the amount and the viscosity grade of HPMC. However, large amount and high viscosity of HPMC caused trouble in molding prior to freeze-drying. Addition of ethylcellulose could retard the release rate of GBP, with relatively low increase in viscosity of paste. Since pores generated by freeze drying imparted buoyancy for gastric retention to FD-GRT, additional materials for buoyancy was not necessary and FD-GRT had no lag time for buoyancy due to low density. Therefore it could be a promising tool for gastroretentive drug delivery.
    Cellulose 12/2013; 20(6). DOI:10.1007/s10570-013-0048-7 · 3.03 Impact Factor
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    ABSTRACT: The purpose of the present study is to investigate the influence of gastric retention of ecabet sodium (ECS) on its mucoprotective effect in rat ulcer models. Mini-tablets containing 9 mg ECS were prepared using the direct compression method. The release rates of ECS mini-tablets were controlled by the amount and viscosity grade of hydroxypropylmethyl cellulose incorporated. Gastric retention of ECS mini-tablets after oral administration to rats was visually confirmed using a fluorescence imaging system. Because ECS mini-tablets exhibited size-dependent gastric retention, their gastric retention time was prolonged as the release rate decreased. In the in vivo efficacy study, gastro-retentive dosage forms of ECS did not influence the mucoprotective effect in the immediate irritation model but enhanced the effect in the delayed irritation model compared with ECS suspension. This finding indicates that the duration of the mucoprotective effect of ECS can be extended by the employment of gastro-retentive dosage formulations and provides a rationale for development of ECS gastro-retentive dosage forms.
    Archives of Pharmacal Research 11/2013; 37(8). DOI:10.1007/s12272-013-0278-0 · 1.75 Impact Factor
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    ABSTRACT: Abstract The purpose of the present study was to prepare desmopressin orally disintegrating microparticles (ODMs) using organic-aqueous crossover coating process which featured an organic sub-coating followed by an aqueous active coating. Sucrose beads and hydroxypropyl cellulose (HPC) were used as inert cores and a coating material, respectively. Characterizations including size distribution analysis, in-vitro release studies and in-vitro disintegration studies were performed. A pharmacokinetic study of the ODMs was also conducted in eight beagle dogs. It was found that sucrose beads should be coated using organic solvents to preserve their original morphology. For the active coating, the aqueous coating solution should be used for drug stability. When sucrose beads were coated using organic-aqueous crossover coating process, double-layer ODMs with round shapes were produced with detectable impurities below limit of US Pharmacopeia. The median size of ODMs was 195.6 μm, which was considered small enough for a good mouthfeel. The ODMs dissolved in artificial saliva within 15 s because of hydrophilic materials including sucrose and HPC in the ODMs. Because of its fast-dissolving properties, 100% release of the drug was reached within 5 min. Pharmacokinetic parameters including Cmax and AUC24 indicated bioequivalence of the ODMs and the conventional immediate release tablets. Therefore, by using the organic-aqueous crossover coating process, double-layer ODMs were successively prepared with small size, round shapes and good drug stability.
    Drug Development and Industrial Pharmacy 11/2013; 41(2). DOI:10.3109/03639045.2013.858742 · 2.10 Impact Factor
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    ABSTRACT: Abstract The aims of the present study were to prepare new dual-mode floating gastroretentive tablets (DF-GRT) containing itraconazole (ITR) and to evaluate influence of the dosage forms on pharmacokinetic parameters of ITR. The solubility of ITR was enhanced around 200 times (from 1.54 to 248.38 µg/mL) by preparing solid dispersion (SD) with hydroxypropylmethyl cellulose. Buoyancy of DF-GRT containing ITR-SD was established by both camphor sublimation and gas generation. Camphor sublimation decreased density of DF-GRT by making pores in tablet matrix, which led to elimination of lag time for floating. Carbon dioxide generated by sodium bicarbonate and citric acid helped to maintain buoyancy of DF-GRT. Therefore DF-GRT floated on the medium without lag time until disintegrated entirely during in vitro release study. They released 89.11% of the drug at 2 h. Residual camphor was <0.5 wt% after sublimation. The pharmacokinetics of DF-GRT was evaluated in six miniature pigs and compared to immediate release tablets (IRT). Mean AUC ratio of GRT/IRT was 1.36 but there was no statistical difference between AUC values. However delayed tmax, increased MRT and equivalent Cmax of DF-GRT supposed it could be a promising tool for gastroretentive drug delivery system containing ITR.
    Drug Delivery 11/2013; 21(7). DOI:10.3109/10717544.2013.853212 · 2.20 Impact Factor
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    ABSTRACT: Four-arm PEG cross-linked hyaluronic acid (HA) hydrogels containing PEGylated tumor necrosis factor (TNF)-related apoptosis-inducing ligand (PEG-TRAIL) were fabricated, and their antitumor effects were evaluated in pancreatic cell (Mia Paca-2)-xenografted mice. HA was conjugated with 4-arm PEG10k-amine (a cross-linker) at ratios of 100: 1 and 100: 2 using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride as a cross-linker, and TRAIL or PEG-TRAIL were incorporated into these HA hydrogels. HA hydrogels at a 100: 1 ratio were prepared in good yields (>88%), were moderately stiff, and gradually released PEG-TRAIL over ∼14 days in vitro and over ∼7 days in vivo (as determined by HPLC and infrared imaging). The released PEG-TRAIL was found to have obvious apoptotic activity in Mia Paca-2 cells. PEG-TRAIL HA hydrogels displayed remarkably more antitumor efficacy than TRAIL HA hydrogels in Mia Paca-2 cell-xenografted mice in terms of tumor volumes (size) and weights (453.2 mm(3) and 1.03 g vs. 867.5 mm(3) and 1.86 g). Furthermore, this improved antitumor efficacy was found to be due to the apoptotic activity of PEG-TRAIL in vivo (determined by a TUNEL assay) despite its substantially lower cytotoxicity than native TRAIL (IC50 values: 71.8 and 202.5 ng/ml, respectively). This overall enhanced antitumor effect of PEG-TRAIL HA hydrogels appeared to be due to the increased stability of PEGylated TRAIL in HA hydrogels. Our findings indicate that this HA hydrogel system combined with PEG-TRAIL should be considered a potential candidate for the treatment of pancreatic cancer.
    Acta biomaterialia 09/2013; 10(1). DOI:10.1016/j.actbio.2013.08.046 · 5.68 Impact Factor
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    ABSTRACT: Inhalable glycol chitosan-coated poly(lactic-co-glycolic acid) (PLGA) nanoparticles containing palmitic acid-modified exendin-4 (Pal-Ex4) (chitosan Pal-Ex4 PLGA NPs) were prepared and characterized. The surface morphology, particle size, and zeta potential of chitosan Pal-Ex4 PLGA NPs were investigated, and the adsorption and cytotoxicity of chitosan Pal-Ex4 PLGA NPs were evaluated in human lung epithelial cells (A549). Finally, the lung deposition characteristics and hypoglycemia caused by chitosan Pal-Ex4 PLGA NPs were evaluated after pulmonary administration in imprinting control region (ICR) and type 2 diabetic db/db mice. Results showed that chitosan Pal-Ex4 PLGA NPs were spherical, compact and had a diameter of ~700 nm and a positive surface charge of +28.5 mV Chitosan-coated PLGA NPs were adsorbed onto A549 cells much more so than non-coated PLGA NPs. Pal-Ex4 release from chitosan-coated PLGA NPs was delayed by as much as 1.5 days as compared with chitosan-coated Ex4 PLGA NPs. In addition, chitosan-coated PLGA NPs remained in the lungs for ~72 hours after pulmonary administration, whereas most non-coated PLGA NPs were lost at 8 hours after administration. Furthermore, the hypoglycemic efficacy of inhaled chitosan Pal-Ex4 PLGA NPs was 3.1-fold greater than that of chitosan Ex4 PLGA NPs in db/db mice. The authors believe chitosan Pal-Ex4 PLGA NPs have considerable potential as a long-acting inhalation delivery system for the treatment of type 2 diabetes.
    International Journal of Nanomedicine 08/2013; 8:2975-83. DOI:10.2147/IJN.S48197 · 4.38 Impact Factor

Publication Stats

523 Citations
188.91 Total Impact Points


  • 2001–2015
    • Sungkyunkwan University
      • School of Pharmacy
      Sŏul, Seoul, South Korea
  • 2012
    • University of Suwon
      Suigen, Gyeonggi Province, South Korea
  • 2008
    • Wonkwang University
      • College of Pharmacy
      Riri, North Jeolla, South Korea
  • 2003
    • Hallym University
      • College of Medicine
      Sŏul, Seoul, South Korea