• Carbon letters
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• v.9 no.4
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• pp.283-288
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• 2008

The composites of temperature-sensitive hydrogel and activated carbons were prepared in order to improve both the mechanical strength of hydrogel matrix and the loading capacity of drug in a hydrogel drug delivery system. The swelling of composite hydrogel was varied depending on the temperature. Both the swelling and the release behavior of the composite hydrogel were varied depending on the kind of activated carbon. The release behavior showed the high efficiency which is important for practical applications.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.139-144
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• 2002

Two types of alginate gel beads capable of floating in the gastric cavity were prepared. The first, alginate gell bead containing olive oil(Al-Oil), is a hydrogel bead and its buoyancy is attributable to olive oil held in the alginate gel matrix. The model drug, metronidazole(MZ), contained in Al-Oil was released gradually into artificial gastric fluid. The profiles of MZ release from Al-Oil shown initial burst and after 90 min they were about 100%. The second, alginate gel bead containing curdlan microsphere(Al-C), is a gel bead with curdlan-MZ microsphere in the matrix. To sustained release rate of drug, alginate bead were prepared curdlan microsphere containing MZ. Results demonstrated that sustained delivery of MZ over 2h can be easily achieved while the bead remained float. The release properties of prepared alginate beads are applicable not only for sustained release of drugs but also for targeting the gastric mucosa.

• Macromolecular Research
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• v.11 no.4
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• pp.273-282
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• 2003

A hydrophilic macromolecular network containing hydrophobic moieties has been prepared by free radical copolymerization of acrylamide and styrene in the presence of poly(vinyl alcohol) (PVA) and its potential as controlled drug delivery carrier was evaluated with tetracycline as a model antibiotic drug. The amount of drug was assayed spectrophotometrically. The network was characterized by optical microscopy, infra-red spectroscopy and structural parameters such as average molecular weight between cross1inks ($M_c$), cross1ink density (q) and number of elastically effective chains ($V_e$) were evaluated. It was found that with increasing concentration of PVA, ST and MBA in the hydrogel, the release rate initially increases but after definite concentrations of the above components the release rate falls. In the case of AM, release rate constantly decreases with increasing AM concentration in the hydrogel.

• Journal of Pharmaceutical Investigation
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• v.26 no.1
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• pp.13-22
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• 1996

Poly(D,L-lactic acid) (PLA) microspheres containing alprazolam(APZ) were prepared by a solvent-emulsion evaporation method and their release patterns were investigated in vitro. Various batches of microspheres with different size and drug content were obtained by changing the ratio of APZ to PLA, PLA concentration in the dispersed phase and stirring rate. Rod-like APZ crystals on microsphere surface, which were released rapidly and could act as a loading dose, were observed with increasing drug content. The release rate was increased with increase in drug contents and decrease in the molecular weight of PLA. The release rate of APZ for long-acting injectable delivery system in vitro, which would aid in predicting in vitro release profile, could be controlled by properly optimizing various factors affecting characteristics of microspheres.

• Journal of Pharmaceutical Investigation
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• v.21 no.2
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• pp.91-95
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• 1991

Polyethylene glycol, polypropylene glycol and block copolymer of ethylene glycol and propylene glycol were crosslinked by triisocyanate to form water swellable, rubbery polymer. The equilibrium swelling of the hydrogels ranged from 3% to 60% according to the hydrophobic-hydrophilic properties of the prepolymers. Model drugs, sodium salicylate and prednisolone were incorporated in the polymer matrices by swelling loading. Physical properties of the drugs affected the drug release mechanisms due to the change in the swelling behaviors of the polymeric devices. Zero order release was observed in the case of relatively hydrophobic polymer matrices.

• Journal of Pharmaceutical Investigation
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• v.24 no.3
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• pp.139-144
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• 1994

The effect of some formulation variables on the release rate of famotidine, a $H_2$ receptor antagonist, from cellulose matrices containing hydroxypropylcellulose (HPC) in different ratios and types was investigated. The effects of tablet shape and compression pressure on dissolution rate of famotidine were studied. And the effect of the pH of dissolution media was also studied. Increase in the ratio of polymer to drug decreased the release rate of famotidine. Increase of the polymer viscosity also decreased the release rate. The release rate of famotidine was dependent on the pH of dissolution media. The release rate of drug was not much dependent on the compression pressure but dependent on the tablet shape and/or surface area. Consequently, the release rate of famotidine can be modified by changing the HPC contents, types of polymers with different viscosity grades or using appropriate fillers.

• Journal of Pharmaceutical Investigation
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• v.24 no.4
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• pp.257-263
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• 1994

The interpenetrating polymer networks (IPNs) of polyacrylic acid (PAA)-polyethylene glycol (PEG) were synthesized via crosslinking of PEG and simultaneous free radical polymerization of PAA. The equilibrium swelling of the IPNs matrices, ranged from 40% to 95%, was varied to a great extent as compared with PAA homopolymer due to the interpolymer interaction between PAA and PEG. The drug release kinetics of drug loaded matrices was significantly affected by the charge of drugs as well as interpolymer complexation.

• KSBB Journal
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• v.25 no.6
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• pp.572-576
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• 2010

Biological products, such as live varicella vaccine, are composed of biological substances derived from biological organisms. It is very difficult to identify these biologics' characteristics by analysis of simple physical and chemical methods alone. So the reference material is essential in order to evaluate the quality of bilogics. The 1'st national standard for varicella live vaccine was manufactured, established in 2002 and 2003, and have been used for the manufacturer's quality control and national lot release since then. As the lack of its availability and the decrease of its stability, this study was initiated by National Institute of Food and Drug Safety Evaluation (NiFDS) in 2008 to manufacture and establish the 2nd national standard for varicella live vaccine. The candidate material was manufactured from one of domestic manufacterers and the joint research of the NiFDS and manufacturers of varicella live vaccine was conducted to estimate of the reliable virus content. In the collaborative study, 3 laboratories including NiFDS performed the virus content test more than 7 times and all assay results were statistically analyzed. The mean coefficient of variation (CV) was 1.24%, and the geometric mean titre (GMT) variation range of each laboratory was low. On the basis of the results of this study, the candidate material of 2nd national standard for varicella live vaccine was assigned a potency of 4.26 log10 pfu/0.5 mL, when reconstituted in 0.7 mL.

• Archives of Pharmacal Research
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• v.12 no.3
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• pp.186-190
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• 1989

The release rates of methotrexate (MTX) from MTX-human serum albumin (HSA) conjugate, and 5-fluorouracil (5-FU) from 5-FU acetic acid (AA)-HSA conjugate were determined after incubation of the conjugates in various conditions. The concentrations of 5-FU released from the conjugate increased monoexponentially, however those of MTX increased biexponentially in all studies. It indicated that there are two distinct types of MTX-HSA linkage, weakly and tightly bound linkages. The release rates of 5-FU were lower than those of MTX in all studies indicating that the bond of 5-FU-AA-HSA conjugate is very stable, which is supported by the higher value of activation energy (39. 9 vs 10. 7 Kcal/mole) using Arrhenius equation. The release rates of MTX and 5 -FU from the conjugates increased with incubation temperatures. Proteolytic enzyme and liver homogenates accelerated significantly the release rates of MTX and 5-FU. Approximately 1.30 and 22.0% of MTX were released after 12 hours of incubation in the absence and presence of protease, respectively. The corresponding values for 5-FU were released after 12 hours of incubation with rat liver homogenates which were diluted 6 times with phosphate buffer of pH 6.0. The MTX-HSA and 5-FU-AA-HSA conjugates were very stable in rat plasma.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.3
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• pp.191-195
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• 2004

Drug delivery systems that are based on pectin have been studied for colon specific delivery using the specific activity of colon microflora. The aim of this study was to design a novel method of manufacturing pectin microspheres without oils and surfactants and to investigate the potential use of the pectin microspheres as an oral colon-specific drug carrier. The pectin microspheres were successfully formed using the spray drying method and crosslinking with calcium chloride. From the crosslinked pectin microspheres, indomethacin (IND) release was more suppressed than its release from non-crosslinked microspheres. In a low pH (pH 1.4) environment, the pectin microspheres released IND at an amount of about 18${\pm}$2% of the total loaded weight for 24 h while the release rate of IND was stimulated at neutral pH (pH 7.4). IND release from the pectin microspheres was increased by the addition of pectinase. The results clearly demonstrate that the pectin microspheres that were prepared by the spray drying and crosslinking methods are potential carriers for colon-specific drug deliveries.