• Journal of Pharmaceutical Investigation
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• v.40 no.1
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• pp.63-66
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• 2010

The "Guidance Document for Bioequivalence Study" was revised for adding to bioequivalence studies of controlled-release products after meal(Korea Food & Drug Administration Notification #2008-22, 2008.5.7). The bioequivalence study design for controlled-release products is $2{\times}2$ crossover under fast and fed condition in respect. For studies of controlled-release products under fed study, the same high-fat diet should be taken within 20 minutes in at least a 10-hour fasting state. The drug products should be administered 30 minutes after the meal started. A high-fat(more than 35 percent of total caloric content of the meal) and high-calorie(over 900 calories) meal is recommended as a test meal for fed BE studies.

• Journal of the Korean Chemical Society
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• v.37 no.5
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• pp.527-536
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• 1993

The characteristics of the controlled drug release were studied for biodegradable transdermal drug delivery system. A biodegradable polymeric matrix was prepared from chitosan, silver sulfadiazine, and glycerine. The release behavior of silver sulfadiazine from chitosan matrix was consistent with the Higuchi's diffusion controlled model. The release time was delayed by increasing the content of silver sulfadiazine and thickness of the matrix, whereas decreased as glycerine concentration increased. The apparent constant (K) of release rate was proportional to the content of drug or glycerine and the thickness of chitosan matrix. These results indicated that chitosan matrix shows some potential as a drug delivery system for transdermal therapeutic application.

• Journal of Microbiology and Biotechnology
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• v.9 no.1
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• pp.50-55
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• 1999

To develop a new form of controlled release dosage for administering for indomethacin (IND), two formulations of IND-loaded nanoparticles were designed based on polysaccharide (guar) derivatives. Nanoparticles prepared by the dialysis method were characterized with respect to morphology, size distribution, drug content, and in vitro drug release. Morphological studies by scanning electron microscopy (SEM) indicated that guar acetate (GA) nanoparticles were spherical in shape and had a smooth surface. The particle size distributions of formulation I (40mg of GA) and formulation II (80mg of GA) were shown to be $250.78\pm185.13nm$ and $718\pm145.90nm$ in distilled water ($20$^{\circ}C$), respectively. The drug loading efficiencies of nanoparticles were approximately 26% and 31% for formulations I and II, respectively. The differential scanning calorimetry (DSC) results indicated that the IND was perfectly distributed within GA nanoparticles. We also found, from the X-ray diffractometry analysis, that a decrease in the degree of crystallinity of the drug occurred in the nanoparticles. No changes between the original IND and the released IND from GA nanoparticles were detected by FT-IR. Using guar acetate, it is possible to design nanoparticles which allow the controlled release of IND over an extended period of time.

• YAKHAK HOEJI
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• v.41 no.1
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• pp.30-37
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• 1997

In order to formulate a controlled release system for oral drug delivery, the microcapsules were prepared in w/o emulsion containing cefaclor as a water-soluble model drug by th e method of interfacial polycondensation. Gelatin wis selected as a suitable polymer for interfacial polycondensation. Gelatin solution containing drug was emulsified in an organic phase under mechanical stirring. After emulsification, terephthaloyl chloride was added as cross linking agent, followed by mechanical stirring, washing and drying. Physical characteristics of microcapsules were investigated by optical microscopy, scanning electron microscopy and particle size analysis. Mean particle sizes of gelatin microcapsules were, in the range, of about 20~50 ${\mu}$m. The microcapsules were in good apperance with spherical shapes before washing, but were destroyed partially after washing and drying, even though some microcapsules were still maintained in their shapes. Contents of cefaclor in the microcapsules were calculated by UV spectrophotometry after 3 days extraction with pH 4 carbonate buffer solution. The effects of cross linking time. pH. concentration of cross-linking agent, and temperature on drug release kinetics have been discussed extensively.

• YAKHAK HOEJI
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• v.31 no.1
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• pp.25-32
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• 1987

The effect of loading dose, plasticiser and PVA molecular weight on naproxen release from hydrophilic polymer matrix was examined. Hydrophilic polymer matrix was prepared with PVA and PVP by adding glycerine as plasticiser. The release of naproxen from polymer matrix was determined in phosphate buffer medium. The release rate of naproxen from the polymer matrix increased as drug loading dose and plasticiser percentage increased. Raproxen released from the polymer matrix showed the time square root kinetics. Without changing the release-pattern, the release rate of naproxen could not be changed by varying molecular weight of PVA. Linearly released time range increased as drug loading dose increased, whereas decreased as plasticiser percentage increased up to 30%.

• Journal of Pharmaceutical Investigation
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• v.26 no.2
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• pp.125-135
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• 1996

Solid lipid nanoparticles(SLN) are particulate systems for parenteral drug administration and suitable for controlled release. SLN were prepared by homogenization process. Dispersion at increased temperature (molten lipid) was performed to yield SLN loaded with lipophilic drugs. Tetracaine base, lidocaine base, prednisolone, methyltestosterone and ethinylestradiol were used as model drugs to access the loading capacity and to study the release behavior. To investigate production parameters(lipids, surfactant concentration, homogenizing rpm) in the formation of SLN, particle size was performed by laser diffraction analysis. The mean particle size of SLN with stearic acid or trilaurin was below 1 micron. By decreasing the particle size and increasing the surfactant concentration, the release rate was increased especially in the case of highly lipophilic drug loaded SLN. Methyltestosterone or ethinylestradiol loaded SLN showed a distinctly prolonged release over a few days.

• KSBB Journal
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• v.18 no.2
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• pp.107-110
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• 2003

Biodegradable polymers, poly(lactic-co-glycolic acid) (PLGA), poly(3-hydroxybutyrate) (PHB), and medium chain length polyhydroxyalkanoates (MCL-PHA) containing rose bengal (model drug) were coated onto the surface of stainless steel (stent materials) and their in vitro release characteristics were investigated. Drug release increased with; decreasing PLGA concentration, increasing rose bengal concentration, and Increasing dip-coating duration. The order of drug release from the polymer coating was: PHB > PLGA > MCL-PHA. These results suggest that drug release can be controlled by: changing the concentration and type of polymer, the drug concentration, and the dip-coating duration.

• YAKHAK HOEJI
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• v.60 no.1
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• pp.46-50
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• 2016

The purpose of this study was the development of sustained-release lyogel of chlorhexidine in the treatment of periodontal diseases. A sustained-release chlorhexidine lyogel (CHX-G) was formulated, based on Eudragit$^{(R)}$ (1~3%), polyvinyl pyrrolidone (PVP) (0~10%), triacetin (20~40%), hydroxy ethyl cellulose (HEC) (1%) and glycerin. In vitro studies were performed to determine the release rate of chlorhexidine from CHX-Gs using dialysis tube. Our results suggest that the release rate of chlorhexidine from lyogel could be controlled by changing the lyogel compositions.

• Journal of Pharmaceutical Investigation
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• v.23 no.4
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• pp.207-211
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• 1993

Reservoir type devices were designed for long-term implantable drug delivery system. The reservoir type device was prepared with the polymethacrylic acid gel coated with polyurethane membrane. Release controlling agent (RCA) were employed to control drug release from devices via generation of micropores in the membranes. The polyurethane membrane functioned as a rate controlling barrier. The drug release pattern of hydrogel demonstrated zero order kinetics. The release rate of drugs could be regulated by varying hydrophobicity/hydrophilicity and content of the RCA, as well as the thickness of the polyurethane membrane. The release of drugs from this system was governed by pore mechanism via simple diffusion and osmotic pressure.

• Polymer(Korea)
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• v.29 no.3
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• pp.260-265
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• 2005

The initial burst of drug release is an important role in the controlled delivery of drug having hish toxicity and narrow therapeutic ranges. Nanosphere composed of monolayer could not achieve precisely controlled drug release because of the initial burst of drug on surface. In this study, double layered nanosphere was prepared for sustained drug delivery without initial burst. Double layered nanosphere composed of dextran and PLGA was fabricated by using conventional W/O/W double emulsion method. To control surface tension on the outer layer of nanospheres, PVA was used as a surfactant. Release behavior of dextran as model drug was observed as the $3{\times}1$mm wafers formed by compression mould in the deionized water for 7 days. Double layered nanosphere has sustained release behavior, in contast to single layered nanospheres. such as mechanical mixture and dextran nanospheres. Especially, nanosphere containing PVA $0.2\%$ has shown nearly the zero-order release profile. As a result of this study, double layered nanospheres has more sustained release profile of drug without the initial burst and the release behavior of dexoan on tile double layered nanospheres was controlled by the contents of PVA as a surfactant.