Biomedical subjects

Min-Soo Kim

Publications and source records attributed to Min-Soo Kim.

9 recordsLinked to original sources

PubMed2006

Recrystallization of fluconazole using the supercritical antisolvent (SAS) process.

The supercritical antisolvent (SAS) process was used to modify solid state characteristics of fluconazole. Fluconazole was recrystallized at various temperatures (60-80 degrees C) and pressures (8-16MPa) using dichloromethane (DCM) as a solvent. Acetone and ethanol were also employed as solvents. The fluconazole polymorphs prepared by the SAS process were characterized by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Furthermore, the equilibrium solubility of the samples in aqueous solution was determined. Fluconazole anhydrate form I was obtained at low temperature (40 degrees C) and anhydrate form II was obtained at high temperature (80 degrees C). The variation of pressure during the SAS process may influence the preferred orientation. Anhydrate forms I and II were also obtained using various solvents. Therefore, it was shown that solid state characteristics of fluconazole, including the polymorphic form and preferred orientation, can be controlled by changing operating conditions of the SAS process such as temperature, pressure, and solvent.

Antifungal Agents↗

PubMed2005

Improved physicochemical characteristics of felodipine solid dispersion particles by supercritical anti-solvent precipitation process.

Solid dispersions of felodipine were formulated with HPMC and surfactants by the conventional solvent evaporation (CSE) and supercritical anti-solvent precipitation (SAS) methods. The solid dispersion particles were characterized by particle size, zeta potential, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), solubility and dissolution studies. The effects of the drug/polymer ratio and surfactants on the solubility of felodipine were also studied. The mean particle size of the solid dispersions was 200-250 nm; these had a relatively regular spherical shape with a narrow size distribution. The particle size of the solid dispersions from the CSE method increased at 1 h after dispersed in distilled water. However, the particle sizes of solid dispersions from the SAS process were maintained for 6 h due to the increased solubility of felodipine. The physical state of felodipine changed from crystalline to amorphous during the CSE and SAS processes, confirmed by DSC/XRD data. The equilibrium solubility of the felodipine solid dispersion prepared by the SAS process was 1.5-20 microg/ml, while the maximum solubility was 35-110 microg/ml. Moreover, the solubility of felodipine increased with decreasing drug/polymer ratio or increasing HCO-60 content. The solid dispersions from the SAS process showed a high dissolution rate of over 90% within 2 h. The SAS process system may be used to enhance solubility or to produce oral dosage forms with high dissolution rate.

Calorimetry, Differential Scanning↗

PubMed2005

Microaffinity purification of proteins based on photolytic elution: toward an efficient microbead affinity chromatography on a chip.

A bead affinity chromatography system, which was based on the photolytic elution method, was integrated into a glass-silicon microchip to purify specific target proteins. CutiCore beads, which were coupled with a photo-cleavable ligand, such as biotin and an RNA aptamer, were introduced into a filter chamber in the microchip. The protein mixture containing target protein labeled with fluorescein isothiocyanate (FITC) was then passed through the packed affinity beads in the microchamber by pressure-driven flow. During the process, the adsorbed protein on the bead was monitored by fluorescence. The concentrated target protein on the affinity bead was released by simple irradiation with UV light at a wavelength of 360 nm, and subsequently eluted with the phosphate buffer flow. The eluted target protein was quantitatively detected via the fluorescence intensity measurements at the downstream of the capillary connected to the outlet of the microchip. The microaffinity purification allowed for a successful method for the identification of specific target proteins from a protein mixture. In addition, the feasibility of this system for use as a diagnosis chip was demonstrated.

Biotin↗

PubMed2005

Adhesive layer properties as a determinant of dentin bond strength.

The goal of this study is to evaluate the hypothesis that the properties of the resin adhesive might affect the microtensile bond strength (MTBS) of multibottle dental adhesive system. In order to alter the properties, the experimental resin adhesives containing 2,2-bis (4-2-hydroxy-3-methacryloyloxypropoxyphenyl)propane (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) at various ratios were prepared. Degree of conversion immediately after curing (DC-immed), degree of conversion at 48 h after curing (DC-48h) of a thin coat of the experimental adhesives, the flexural strength (FS) of the bulk specimens made of the experimental adhesives, pH, viscosity at shear rate of 1 S(-1), and the microtensile bond strength (MTBS) values of the adhesives to dentin were investigated. The maximum MTBS and FS values of the resin adhesives were observed when the ratio of Bis-GMA/TEGDMA was 60/40. However, pH and viscosity values increased with increasing Bis-GMA content in the adhesives. When Bis-GMA content was more than 60 wt %, the viscosity increased exponentially and restricted the DC and FS, and accordingly decreased the bond strength. The stronger the resin adhesives were, the higher the bond strength to dentin could be obtained.

Bisphenol A-Glycidyl Methacrylate↗

PubMed2005

Reparation of controlled release spheronized beads by simple extrusion and modified spheronization process.

Beads loaded with the water-soluble drug, phenylpropanolamine HCl (PPA), were prepared using an extruder and double arm counter-rotating roller modified from a traditional pill machine. The mean diameter of the cylindrical rod-like extrudate from the ram extruder was 3 mm; that of the uncoated bead after cutting and spheronization by the modified double arm counter-rotating roller was 3.26-3.28 mm. Although the surface of the beads was moderately rough and irregular, some exhibited hump-shaped protrusions, the sphericity was acceptable (roundness 1.15) and adequate for the subsequent coating process. An increase in mean diameter of the coated beads and improvements in friability and sphericity were observed in proportion to the amount of coating material applied (ethylcellulose or Eudragit RS 100). It was also found that the release rate of PPA from the coated beads could be controlled by the amount and type of coating materials applied or with the incorporation of Eudragit RS 100 into the core matrix. Further modifications to the double arm counter-rotating roller, including adjustment of the rotation speed and distance between the rollers, would yield smaller uncoated beads with improved roundness and surface roughness. In conclusion, the present method could be potentially applied to prepare controlled release drug delivery beads or pellet dosage forms.

Delayed-Action Preparations↗

PubMed2005

The influence of Surelease and sodium alginate on the in-vitro release of tamsulosin hydrochloride in pellet dosage form.

The objective of this study was to prepare controlled-release pellets containing 0.2 mg tamsulosin hydrochloride using a pelletizer-equipped piston extruder and double-arm counter-rotating rollers with Surelease and sodium alginate. The release of tamsulosin HCl from pellets coated with the commercial aqueous ethylcellulose dispersion (Surelease) was investigated at different coating loads. In addition, the effect of sodium alginate on drug release was investigated by varying the ratio of sodium alginate to microcrystalline cellulose (MCC). Dissolution studies were first performed in 500 mL simulated gastric fluid (pH 1.2) containing 0.003% (w/w) polysorbate 80 and then in simulated intestinal fluids (pH 7.2). The morphology of pellet surfaces and cross sections were examined by scanning electron microscopy (SEM). Apparently, the spherical pellets were prepared using a pelletizer-equipped piston extruder and double-arm counter-rotating rollers. The release profiles of tamsulosin HCl from Surelease-coated pellets were significantly affected by changing the content of Surelease, the pH of the dissolution medium and the ratio of sodium alginate to MCC. The drug release rates not only decreased with increase in the coating load, but also increased when the pH of the dissolution medium was increased from 1.2 to 7.2 regardless of the sodium alginate-to-MCC ratio. Moreover, the drug release rate at pH 7.2 was gradually increased by increasing the ratio of sodium alginate to MCC. SEM showed smooth surfaces of Surelease-coated pellets. These results suggest that Surelease and sodium alginate would be useful excipients in the preparation of controlled-release pellets with the desired release profiles.

Alginates↗

PubMed2005

Controlled release tamsulosin hydrochloride from alginate beads with waxy materials.

The objective of this study was to develop oral controlled release delivery systems for tamsulosin hydrochloride (TSH) using alginate beads with various waxy materials, such as Compritol 888 ATO, Precirol ATO 5 and Gelucires. The beads were prepared from sodium alginate-waxy material-TSH slurry dropped onto calcium chloride to form spherical beads. The effects of the addition of various waxy materials to alginate beads on the drug encapsulation efficiency, bead size and morphology were investigated. The drug encapsulation efficiency significantly increased with the addition of waxy materials. The TSH-loaded alginate beads with and without waxy materials were almost spherical particles with an average diameter of 1.44 and 1.22 mm, respectively. In dissolution study, the TSH-loaded alginate beads with waxy materials exhibited controlled release behaviour over a 6-h period, while beads without waxy materials showed release of 100% TSH within 2 h. These results may be attributed to the formation of a more rigid alginate matrix structure due to incorporated waxy materials. From the Dunnett's t-test and the f2 factor, the release of TSH from alginate beads, a similar dissolution pattern to that of the marketed product (Harunal capsules) could be achieved by adding Gelucire 50/13 into TSH-loaded alginate beads. From these results, oral controlled release of TSH could be achieved with loading in alginate beads with waxy materials, such as Compritol 888 ATO, Precirol ATO 5 and Gelucires.

Adrenergic alpha-Antagonists↗

PubMed2005

Cefuroxime axetil solid dispersions prepared using solution enhanced dispersion by supercritical fluids.

Cefuroxime axetil (CA) solid dispersions with HPMC 2910/PVP K-30 were prepared using solution enhanced dispersion by supercritical fluids (SEDS) in an effort to increase the dissolution rate of poorly water-soluble drugs. Their physicochemical properties in solid state were characterized by differential scanning calorimeter (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared spectrometry (FT-IR) and scanning electron microscopy. No endothermic and characteristic diffraction peaks corresponding to CA were observed for the solid dispersions in DSC and PXRD. FTIR analysis demonstrated the presence of intermolecular hydrogen bonds between CA and HPMC 2910/PVP K-30 in solid dispersions, resulting in the formation of amorphous or non-crystalline CA. Dissolution studies indicated that the dissolution rates were remarkably increased in solid dispersions compared with those in the physical mixture and drug alone. In conclusion, an amorphous or non-crystalline CA solid dispersion prepared using SEDS could be very useful for the formulation of solid dosage forms.

Anti-Bacterial Agents↗

PubMed2002

Enhancement of NK cytotoxicity, antimetastasis and elongation effect of survival time in B16-F10 melanoma cells by oregonin.

We investigated the antitumor activity of oregonin, a diarylheptanoid derivative purified from Alnus hirsuta Turcz, Betulaceae. Oregonin is a potential novel immunomodulator, which augments the activation of natural killer (NK) cells, and thereby leads to a powerful antitumor activity. To evaluate the cytotoxicity of oregonin against tumor cells, we examined the effectiveness of NK cells and determined that oregonin could increase NK cell cytotoxicity. This was confirmed by MTT assay. In addition, the survival time of C57BL/6 mice were measured by inoculating B16-F10 melanoma cells to mice via intra muscular (i.m.) injection. Oregonin treatment after 10 hours of inoculation at 10 mg/kg dosage showed a significant extension of survival time by up to 51.32%, when compared to the control group. Moreover, oregonin significantly reduced the incidence of pulmonary metastasis, which may be developed from B16-F10 melanoma cells. These findings suggest that oregonin may be classified as a new and novel immunomodulator due to its potential antitumor activity.

Animals↗