• Journal of Veterinary Clinics
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• v.19 no.2
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• pp.228-235
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• 2002

Mastitis is the most costly disease results in lost milk production, decreased milk quality, milk discard, early culling of cows, drug costs and labor costs in dairy cow. Until now, a antibiotic administration at the end of lactation, dry cow therapy has been known the most effective and widely used mastitis control method. However, dry cow therapy do not control a new infection in the late dry and prepartum period because dry cow products have only persistent activity in the early dry period. Therefore, this study was conducted to evaluate clinical effect of sustained released biodegradable cephalexin microsphere using PLGA in bovine mastitis control during dry period. PLGA has been approved as controlled drug release system because of non-toxic, non-tissue reactive and bioerodible characteristics. This study revealed that cephalexin microsphere had a spherical shape with characteristic porous structure on the surface. Also, in vitro drug release studies are clearly observed that the release rate of cephalexin from PLGA microsphere decrease during the first 21 days after initial burst and then increase again between 3 and 4 weeks showing pulsatile releasing pattern. On the other hand, as tried in field the new infection rate, cure rate and mean SCC after parturition in cephalexin microsphere infused group were significantly differenced as compared to the control group. Accordingly, a sustained release of cephalexin from a biodegradable microsphere could make dry cow therapy more efficiently by preventing a new infection and decreasing the number of existing infection of mammary gland during dry period.

• Journal of Biomedical Engineering Research
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• v.9 no.1
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• pp.73-78
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• 1988

The polymer electrolyte complex hydrogels consisting of poly (methacrylic acid) and poly (4-vinylpyrridine) were formed and 5-flurouracil and pilocarpine drugs were loaded on their hydrogels. Cumulative 5-FU released from PEC hydrogel was affected by the degree of loading and release rate of 5-FU was followed by the monolithic type. Cumulative pilocarpine released from PEC hydrogel increased by ionic interaction between cationic pilocarpine and anionic PMA. Release rate showed the zero order after burst effect.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.247.1-247.1
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• 2003

Iron deficiency is the most common nutritional problem worldwide. Oral iron supplementation programs have failed because of noncompliance and gastrointestinal toxicity. The purpose of this study was to explore the possibility of alginate gel bead as an oral controlled release system of iron supplements and increase the stability of iron succinyl casein (ISC). Alginate beads containing ISC were prepared by the gelation of sodium alginate with calcium cations. The release profiles of ISC were investigated according to the concentration of polymer, the drug/sodium alginate ratio, the concentration and type of cation, curing time and pH of calcium chloride solution. (omitted)

• Journal of Pharmaceutical Investigation
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• v.32 no.3
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• pp.185-190
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• 2002

To improve the solubility of poorly water-soluble drug and to develop a sustained release tablets, the need for the technique, the formation of solid dispersion with polymeric materials that can potentially enhance the dissolution rate and extent of drug absorption was considered in this study. The 1:1, 1:4, and 1:5 solid dispersions were prepared by spray drying method using PVP K30, ethanol and methylene chloride. The dissolution test was carried out at in phosphate buffer solution at $37^{\circ}C$ in 100 rpm. Solid dispersed drugs were examined using differential scanning calorimetry and scanning electron microscopy, wherein it was found that felodipine is amorphous in the PVP K30 solid dispersion. Felodifine SR tablets were prepared by direct compressing the powder mixture composed of solid dispersed felodipine, lactose, Eudragit and magnesium stearate using a single punch press. In order to develop a sustained-release preparation containing solid dispersed felodipine, a comparative dissolution study was done using commercially existing product as control. The dissolution rate of intact felodipine, solid dispersed felodipine and its physical mixture, respectively, were compared by the dissolution rates for 30 minutes. The dissolution rates of felodipine for 30 minutes from 1:1, 1:4, 1:5 PVP K30 solid dispersion were 70%, 78% and 90%. However, dissolution rate offelodipine from the physical mixture was 5% of drug for 30 minutes. Our developed product Felodipine SR Tablet showed dissolution of 17%, 50% and 89% for 1, 4, and 7 hours. This designed oral delivery system is easy to manufacture, and drug releases behavior is highly reproducible and offers advantages over the existing commercial product. The dissolution rate of felodipine was significantly enhanced, following the formation of solid dispersion. The solid dispersion technique with water-soluble polymer could be used to develop a solid dispersed felodipine SR tablet.

• Polymer(Korea)
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• v.26 no.5
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• pp.680-690
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• 2002

Implantable biodegradable wafers were prepared with pamidronate -loaded poly (L-lactide-co-glycolide) (PLGA, 75 : 25 mole ratio by lactide to glycolide, molecular weight : 20000 and 90000 g/mole) by direct compression method for the sustained release of pamidronate to investigate the possibility for the treatment of bone resorption. Pamidronate-loaded PLGA powders were prepared by means of physical mixing and spray drying with the control of formulation factors and characterized by scanning electron microscope and X-ray diffractometer. The pamidronate-loaded PLGA powders fabricated into wafers by direct compression under the constant pressure and time at room temperature. These wafers were also observed for their structural characteristic, release pattern, and degradation pattern. The release rate of pamidronate increased with increasing their initial loading ratio as well as increasing wafer thickness. The molecular weight of PLGA affects the release pattern : the higher molecular weight of PLGA, the faster release rate. It can be explained that the higher viscosity of high molecular PLGA solution at same concentration tends to aggregate PLGA and pamidronate resulting in unstable pharmaceutical dosage form. This system had advantages in terms of simplicity in design and obviousness of drug release rate and nay be useful as an implantable dosage form for the treatment of aural cholesteatoma.

• Journal of the Korean Society of Visualization
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• v.4 no.2
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• pp.6-10
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• 2006

The functional spherical microcapsules were produced through the innovative conjunction of the well-defined amphiphilic block copolymer and the stable droplet phase flow in the micro chemical plant. The microcapsules were formed to have hollow inner cavity and outer surface wall with nano-pores. To examine the potential of encapsulating foreign biochemical molecules, Congo-red dye was loaded into the microcapsule. The release performance in the specific surroundings such as temperature, pH and time was evaluated quantitatively.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.553-553
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• 2003

I. Objectives Endodontic disease is caused primarily by bacteria that interact with periradicular host from the root canal system. Chlorhexidine gluconate is known to effective to eliminate Enterococcus faecalis which resists to other intracanal medicaments. The aim of this in vitro study was to develop a slowly releasing root canal disinfectant using using chlorhexidine gluconate and chitoic acid. II. Materials and Methods Three different group were prepared with different drug release mechanism. In group A, paper points as used core material were loaded with 20% chlorhexidine gluconate.(omitted)

• Journal of Pharmaceutical Investigation
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• v.37 no.4
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• pp.229-235
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• 2007

Multi-layered granules were prepared by a fluidized-bed coater and uniformed granules were obtained with a size range between $950{\sim}1000{\mu}m$ in diameter. The granule system was composed of three layers, i.e. seed layer with sugar sphere bead and a water-swellable polymer, middle layer with a drug, solubilizer and polymer, and the top layer of porous membrane with a polymeric binder. The aim of this work is to find out the dependence of a drug dissolution rate on the amount of a water-soluble binder and a solubilizer in the granule system. The results showed that the higher amount of hydrophilic binder in the porous membrane, gave the bigger pore size and porosity and made faster dissolution rate and also the higher amount of solubilizer in drug layer enhanced the dissolution rate of drug.

• Journal of Pharmaceutical Investigation
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• v.39 no.2
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• pp.85-91
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• 2009

Microcrystallized cellulose xanthate-metal-oxytetracycline complexes (MCX-metal-OTC) were prepared and evaluated as a controlled release system for the antibiotics. Microcrystallized cellulose (MC) was chemically modified to xanthated microcrystallized cellulose (MCX). One-bath method, where MCX was reacted with OTC-metal complexes, afforded greater amount of OTC bound to the polymeric matrix than did two-bath method, where MCX-metal complexes were treated with OTC. The OTC release from MCX-metal-OTC was greatly sustained compared with that from a mixture of MC/metal/OTC. Furthermore, MCX-metal-OTC manifested antibacterial activity, which lasted for 11-18 days. These results suggest that MCX-metal-OTC is a polymeric antibiotics with prolonged antibacterial activity.

• Journal of Pharmaceutical Investigation
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• v.41 no.2
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• pp.103-109
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• 2011

The objective of the study was to prepare self-microeulsifying drug delivery system (SMEDDS) incorporating atorvastatin calcium and evaluate its properties and oral bioavailability. Solubility of atorvastatin in various vehicles was determined. Pseudo-ternary phase diagrams were constructed to identify the good self-emulsification region. The droplet size distributions of the resultant emulsions were determined by dynamic light scattering measurement. The mean droplet size of chosen formulation (20% ethyl oleate, 40% tween-80, 40% Carbitol$^{(R)}$) was $23.4{\pm}1.3$ nm. The SMEDDS incorporating atorvastatin calcium appeared to be associated with better performance in dissolution and pharmacokinetic studies, compared with raw atorvastatin calcium. In dissolution test, the release percentage of atorvastatin from SMEDDS mixture could rapidly reach more than 95% within 3 min. Oral $AUC_{0{\rightarrow}8hr}$ values in SD rats was $1994{\pm}335\;ng{\cdot}hr/mL$, which significantly increased (P<0.05) compared with raw atorvastatin calcium. The SMEDDS formulation was relatively stable when stored at $4^{\circ}C$ during 3 months. Our studies illustrated the potential use of SMEDDS for the delivery of hydrophobic compounds, such as atorvastatin, by the oral route.