• YAKHAK HOEJI
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• v.45 no.6
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• pp.623-633
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• 2001

Various bupivacaine-loaded microspheres were prepared using poly(d,1-lactide) (PLA) and poly(d,1-lactic-co-glycolide) (PLGA) by a solvent evaporation method for the sustained release of drug. The effects of process conditions such as drug loading, polymer type and solvent type on the characteristics of microspheres were investigated. The prepared microspheres were characterized for their drug loading, size distribution, surface morphology and release kinetics. Drug loading efficiency and yield of PLGA micro- spheres were higher than those of PLA microspheres. The prepared microspheres had an average particle size below 5${\mu}{\textrm}{m}$. The particle size range of microspheres was 1.65~2.24${\mu}{\textrm}{m}$. As a result of SEM, the particle size of PLA microspheres was smaller than that of PLGA microspheres. In morphology studies, microspheres showed a spherical shape and smooth surface in all process conditions. In thermal analysis, bupivacaine-loaded microspheres showed no peaks originating from bupivacaine. This suggested that bupivacaine base was molecular-dispersed in the polymer matrix of microspheres. The release pattern of the drug from microspheres was evaluated for 96 hours. The initial burst release of bupivacaine base decreased with increasing the molecular weight of PLGA, and the drug from microspheres released slowly. In conclusion, bupivacaine-loaded microspheres were successfully prepared from poly(d,1-lactide) and poly (d,1- lactic-co-glycolide) polymers with different molecular weights allowing control of the release rate.

• Journal of Biomedical Engineering Research
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• v.16 no.3
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• pp.367-375
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• 1995

Ampicillin sodium (AMP-Na) was loaded Into fibrin glue (FG) in two different ways and was tried to achieve sustained release from FG. One was loading of AMP-Na in a simple mixing and the other was loading of bovine serum albumin (BSA) microspheres which contained ANP-Na. In case of simple mixing, the release control of AWP-Na from FG was tried by variation of FBNG concentration, but failed. However, the loading of BSA mlcrosphere containing ANP-Na into FG showed sustained re- lease of AMP-Na, especially when microsphere was crosslinked with glutaraldehyde (tO.9 : 33hr). The maximum adhesive strength of FG showed at concentration of FBWG and thrombin, 5.0 % and 25-50 NIHU/ml, respectively. The concentration of Factor Xlll (0-500 U/1g of FBNG) did not affect the adhesive strength of FG. The optimal incubation time was 60 min. The AMP-Na or BSA microsphere which was loaded into FG had no significant effect on the adhesive strength of FG.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.5
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• pp.2335-2340
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• 2014

Paclitaxel is hydrophobic in nature and is recognized as a highly toxic anticancer drug, showing adverse effects in normal body sites. In this study, we developed a polymeric nano drug carrier for safe delivery of the paclitaxel to the cancer that releases the drug in a sustained manner and reduces side effects. N-isopropylacrylamide/vinyl pyrrolidone (NIPAAm/VP) nanoparticles were synthesized by radical polymerization. Physicochemical characterization of the polymeric nanoparticles was conducted using dynamic light scattering, transmission electron microscopy, scanning electron microscopy and nuclear magnetic resonance, which confirmedpolymerization of formulated nanoparticles. Drug release was assessed using a spectrophotometer and cell viability assays were carried out on the MCF-7 breast cancer and B16F0 skin cancer cell lines. NIPAAm/VP nanoparticles demonstrated a size distribution in the 65-108 nm range and surface charge measured -15.4 mV. SEM showed the nanoparticles to be spherical in shape with a slow drug release of ~70% in PBS at $38^{\circ}C$ over 96 h. Drug loaded nanoparticles were associated with increased viability of MCF-7 and B16F0 cells in comparison to free paclitaxel. Nano loaded paclitaxel shows high therapeutic efficiency by sustained release action for the longer period of time, i increasing its efficacy and biocompatibility for human cancer therapy. Therefore, paclitaxel loaded (NIPAAm/VP) nanoparticles may provide opportunities to expand delivery of the drug for clinical selection.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.411.1-411.1
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• 2014

This study evaluates the utility of an antibacterial microneedle composed of green tea extract (GT) and hyaluronic acid (HA), for the efficient delivery of GT. These microneedles have the potential to be a patient-friendly method for the conventional sustained release of drugs. In this study, a fabrication method using a mold-based technique to produce GT/HA microneedles with a maximum area of ${\sim}60mm^2$ with antibacterial properties was used to manufacture transdermal drug delivery systems. Fourier transform infrared (FTIR) spectrometry was carried out to observe the potential modifications in the microneedles, when incorporated with GT. The degradation rate of GT in GT/HA microneedles was controlled simply by adjusting the HA composition. The effects of different ratios of GT in the HA microneedles were determined by measuring the release properties. In HA microneedles loaded with 70% GT (GT70), a continuous higher release rate were sustained for 72 h. The in vitro cytotoxicity assays demonstrated that GT/HA microneedles are not generally cytotoxic to chinese hamster ovary cells (CHO-K1), human embryonic kidney cells (293T), and mouse muscle cells (C2C12), which were treated for 12 and 24 h. Antimicrobial activity of the GT/HA microneedles was demonstrated by ~95% growth reduction of gram negative [Escherichia coli (E. coli), Pseudomonas putida (P. putida) and Salmonella typhimurium (S. typhimurium)] and gram positive bacteria [Staphylococcus aureus (S. Aureus) and Bacillus subtilis (B. subtilis)], with GT70. Furthermore, GT/HA microneedles reduced bacterial growth in the infected skin wound sites and improved skin wound healing process in rat model.

• Korean Journal of Environmental Agriculture
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• v.11 no.2
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• pp.155-162
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• 1992

In order to extend the releasing period of granular formulation to approximately 20 days, the KC-6620-adsorbed granules were formulated with carriers and polyethylene glycol as adjuvant. The releasing rates of active ingredient from the formulations were evaluated in aqueous medium. The baked bentonite was found most effective carrier to sustain the release of KC-6620. Due to, however, low releasing rate of active ingredient after 20 days, bentonite formulation appeared to be of no practical for the short-term sustained release of KC-6620. The increased pore volume of bentonite granular formulation by adding pyrophyllite increased remarkably the released amount of KC-6620 from bentonite-pyrophyllite(4 : 6) granule up to 85% of total active ingredient incorporated. Addition of polyethylene glycol to the bentonite-pyrophyllite granule further increased the releasing rate of KC-6620. With KC-6620 content in the bentonite-pyrophyllite(4 : 6) granule, the releasing rate of active ingredient was markedly reduced.

• Polymer(Korea)
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• v.35 no.5
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• pp.483-487
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• 2011

For the preparation of effective non-vascular drug eluting stent (DES), pullulan acetate (PA) was investigated as a coating material for polytetrafluorethylene (PTFE)-covered stent. PA was coated on PTFE-covered stent (PTFE-stent) by dip coating technique, and then its surface morphology, drug release behavior and cellular toxicity were tested. Field emission-scanning electron microscopy (FE-SEM) result indicated that its surface was smoother after PA coating without any cracking. The sustained release behavior of paclitaxel from PA-coated PTFE membrane was observed for 80 days. Also, the biological stability of paclitaxel in the membrane was confirmed by annexin V binding assays. Furthermore, the antitumor activity was demonstrated by an in vivo test against CT-26 murine colorectal tumors. From the results, we concluded that PA was expected as a useful coating material to design an effective non-vascular DES.

• Polymer(Korea)
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• v.36 no.2
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• pp.182-189
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• 2012

In this study, poloxamer hydrogels were prepared by electron beam irradiation and evaluated for potential application as a buccal mucoadhesive drug delivery system. Poloxamer, one of typical thermoresponsive polymers, was modified to have vinyl end groups for crosslinking reaction, and its hydrogels were fabricated by irradiation crosslinking reaction. Carbopol as a mucoadhesive polymeric additive was introduced to improve the mucoadhesive property of the hydrogels and its effect on the mucoadhesion and drug release properties was investigated. The results showed that the end group modification of poloxamer and the addition of carbopol improved mucoadhesive force and mechanical properties and led to a sustained drug release behavior.

• YAKHAK HOEJI
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• v.44 no.6
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• pp.511-520
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• 2000

Various bupivacaine-loaded microspheres were prepared from poly (d,l-lactide) (PLA) or poly (d,l-lactic-co-glycolide) (PLGA) by a solvent evaporation method for the sustained release of drug. PLA and PLGA microspheres were prepared by w/o/w and w/o/o multiple emulsion solvent evaporation, respectively. The effects of process conditions such as emulsification speed, emulsifier type, emulsifier concentration and internal/external phase ratio on the characteristics of microspheres were investigated. The prepared microspheres were characterized for their drug loading, size distribution, surface morphology and release kinetics. Drug loading efficiency was higher in the microspheres prepared by w/o/o multiple emulsion than that by w/o/w multiple emulsion method, because the solubility of bupivacaine HCI was decreased in oil phase compared with water phase. The prepared microspheres had an average diameter between 1 and $2\;{\mu}M$ in all conditions of two methods. In morphology studies the PLA microspheres showed an irregular shape and smooth surface, but PLGA microspheres had a spherical shape and smooth surface. The release pattern of the drug from microspheres was evaluated on the basis of the burst effect and the extent of the release after 24h. The in vitro release of bupivacaine HCl from microspheres showed a large initial burst release and $60{\sim}80%$ release within one day in all conditions of two methods. The extents of the burst release against PLA and PLGA microspheres were $30{\sim}50%$ and $50{\sim}80%$ within 20min, respectively. This burst release seems to be due to the smaller size of microspheres and the solubility of drug in water.

• Polymer(Korea)
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• v.37 no.1
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• pp.28-33
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• 2013

Zaltoprofen, a propionic acid derivative non-steroidal anti-inflammatory drug, was known to have powerful inhibitory effects on acute, subacute and chronic inflammation. For initial release and sustained release, the microspheres were prepared using an emulsion-solvent evaporation method like an O/W emulsion method with varying the ratio of zaltoprofen-loaded polyoxalate (POX)/PLGA micropheres. The morphology of the microspheres was confirmed by scanning electron microscopy. The crystallinity of microspheres was analyzed by X-ray diffraction and differential scanning calorimeter. Fourier transform infrared spectroscopy was used to analyze the chemical structure of microspheres. The increased ratio of POX microspheres affected the initial drug release, and the sustained release of drug was influenced by ratio of PLGA microspheres. In this study, the initial release behavior of zaltoprofen can be controlled by the ratio of POX/PLGA microspheres.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.417.2-418
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• 2002

The rhGH-loaded PLGA microsphere formulation was prepared using a double emulsion process from hydrophilic 0:50 poly(D.L-lactide-co-glycolide) (PLGA) polymers. To investigate the sustained efficacy of this formulation, ts pharmacodynamic characteristics were analyzed. It showed particle size of ca 53.1 $\mu\textrm{m}$ with high drug ncorporation efficiency and it was sucutaneously administrated to hypophysectomized rats and whole body rowth responses of this formulation were compared to those of the different dosing patterns of rhGH. (omitted)