• Journal of Pharmaceutical Investigation
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• v.28 no.3
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• pp.177-183
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• 1998

Low toxicity, reverse thermal gelation and high drug loading capabilities suggest that poloxamer 407 gels have great potential as a topical drug delivery system. Kojic acid (KA) is an antimelanogenic agent which has been widely used in cosmetics to whiten the skin color. However, it has the drawbacks of skin irritancy due to its acidic pH. Poloxamer gels of different polymer contents were formulated to overcome the problem and compared to the cream type formulations of either w/o/w multiple emulsion cream or o/w type emulsion cream. Using Franz diffusion cells mounted with a synthetic cellulose membrane (MWCO 12,000), drug release characteristics of the formulations were evaluated by the HPLC assay of KA concentration in the receptor compartment of pH 7.4 phosphate buffered saline solutions. Drug release from w/o/w multiple emulsion cream was controlled by oil membrane, showing the apparent zero order release kinetics. The KA release from the poloxamer gels was also controlled by the gel matrix, showing that drug release increased linearly as KA contents increase, but decreased exponentially as the polymer contents increase. In the skin irritancy test, the primary irritancy index(PII) of poloxamer gel base was lower than those of multiple emulsion cream base and o/w cream. Depending on KA contents or polymer contents in the gel. PH values in poloxamer gels were ranged from 1.3 to 2.0, which are interpreted as low or negligible irritation on skin. There was a good correlation between the log value of flux in drug release and PII value in skin irritation. It was possible to conclude that the poloxamer gels containing KA might be a good candidate for an antimelanogenic topical delivery system by virtue of the controlled release of the drug and the reduced skin irritancy.

• Journal of Biomedical Engineering Research
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• v.36 no.6
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• pp.291-295
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• 2015

Various types of implantable drug delivery devices have attracted significant attention for several decades to improve drug bioavailability and reduce side effects, thus enhancing therapeutic efficacy and patients' compliance. However, when implanted into the body, the devices may be influenced by the changes in physiological condition, such as temperature, pH or ionic concentration. Thus, the drug release rates could be also altered concurrently. Therefore, in this work, we employed an implantable ALZET$^{(R)}$ Osmotic Pump, which has been widely used to locally deliver various therapeutic agents and examined the effect of pH, temperature and ionic concentration on its drug release rate. For this, we performed in vitro cell tests to simulate the condition of local tissues influenced by the altered drug release rates, where we used diclofenac sodium as a model drug.

• Journal of the Korean Wood Science and Technology
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• v.48 no.4
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• pp.431-449
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• 2020

Structural property of most hydrogels is soft, resulting in low mechanical performance that limits their usage in the biomedical applications. For overcoming the drawback, cellulose nanocrystals (CNCs) were adopted in this study. Effects of CNCs on characteristics and drug delivery performance of poly (vinyl alcohol) based hydrogels were explored. FT-IR results showed that the fabricated hydrogels had semi-IPN (semi-interpenetrating polymer network) by formation of acetal and aldehyde bridge. Water absorption and swelling ratio decreased with increasing CNCs content, and the hydrogels with CNCs showed better viscoelastic performance than the without CNCs. Also, CNCs mostly improved the ability of the hydrogel to absorb the drug and the sustainability of the drug release. These results demonstrated that incorporating CNCs into the hydrogel systems can be a good alternative to improve drug delivery performance and mechanical property of the hydrogels.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7549-7554
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• 2015

The aim of this study was to develop gastric retentive bi-layered tablet using floating drug delivery technique. Metformin was selected as a model drug due to its narrow absorption window as well as very highly water solubility. These properties of metformin led to be difficult controlling the drug release. The bi-layered tablet was prepared with bi-layered compression machine to minimize interference between floating part and controlling part. The tablet weight, appearance and hardness were evaluated after compression process. The times of 'time to floating' and 'Floating duration' were tested for floating ability and drug release study was also carried out to understand drug release behavior. Furthermore, the drug release of bi-layered tablet was compared with marketed metformin tablet with sustained release pattern (Glucopharge XR$^{(R)}$).The floating ability and drug release behaviors were well controlled by changing amounts of $NaHCO_3$ (floating substance) and hydroxypropyl methylcellulose (HPMC; release control material). Bi-layered tablet had 13s of time to float, over 10h of floating duration and very similar drug release behavior compared with Glucopharge XR$^{(R)}$($f_2$: 89.6). Consequently, the bi-layered tablet with floating ability was successfully prepared and these properties can maximize the efficacy of metformin.

• 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.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.655-659
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• 2003

Solid lipid nanoparticle (SLN) system has been attracted increasing attention during last few years as a potential drug delivery carrier However, the SLN have disadvantage of low encapsulation efficiency for hydrophilic drug. In this study, for increase it's encapsulation efficiency, we prepared the $Eudragit^{\circledR}$ L100-55 (eudragit) coated SLN(E-SLN) based on solvent evaporation method and melt dispersion technique, and analyzed their physicochemical properties in terms of particle size, morphology, and encapsulation efficiency. As a result, they have a ${\pm}150$ nm particle size, spherical shape, and $10^{\sim}25$ % loading efficiency. SLN consists of coconut oil as core material, ascorbic acid and okyong-san as hydrophilic drug.

• Journal of Pharmaceutical Investigation
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• v.41 no.1
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• pp.1-7
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• 2011

The effects of different formulation variables including pressure sensitive adhesive (PSA), permeation enhancer, thickness of the matrix and loading amount of drug on the transdermal absorption of galantamine were investigated across the hairless mouse skin. The permeation profile of galantamine was different depending on the types of PSA, loading amount of drug, thickness of the matrix and type of enhancer used. Highest flux of galantamine was obtained from acrylic PSA but crystals were formed in the patch within 72 h. Among the PSAs screened, crystal formation was not observed only in the patches formulated in Styrene Butadiene Styrene (SBS) matrix. Permeation rate increased linearly as the concentration of galantamine in SBS matrix increased from 2.5 to 15% w/w. Among the enhancers screened, Brij$^{(R)}$ 30 provided highest flux of galantamine. Matrix thickness of 80 ${\mu}m$ was optimum for maintaining adhesiveness as well as consistently delivering galantamine for longer period of time.

• Carbon letters
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• v.11 no.3
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• pp.211-215
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• 2010

Multi-walled carbon nanotube (MWCNT)/poly(vinyl alcohol) (PVA) nanocomposite hydrogels were prepared by freezingthawing method for the electro-responsive transdermal drug delivery. MWCNTs were used as the functional ingredient to improve both mechanical and electrical properties of MWCNT/PVA nanocomposite hydrogels. The morphology of nanocomposites revealed the uniform distribution of MWCNTs and the good interfacial contact. The compression moduli of hydrogel matrices increased greatly from 40 to 1500 kPa by forming MWCNT/PVA nanocomposites. The swelling ratio of MWCNT/PVA nanocomposites decreased as the content of MWCNTs increased under no electric voltage applied. However, the swelling ratio of MWCNT/PVA nanocomposites increased as the content of MWCNTs increased under electric voltage applied and the applied electric voltage increased. The drug was released in the electro-responsive manner through the skin due to the electro-sensitive swelling characteristics of MWCNT/PVA nanocomposite hydrogels.

• Journal of Pharmaceutical Investigation
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• v.41 no.5
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• pp.263-272
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• 2011

Tablet dosage forms have been preferred over other formulations for the oral drug administration due to their low manufacturing costs and ease of administrations, especially controlled-release applications. Controlled-release tablets are oral dosage forms from which the active pharmaceutical ingredient (API) is released over an intended or extended period of time upon ingestion. This may allow a decrease in the dosing frequency and a reduction in peak plasma concentrations and hence improves patient compliance while reducing the risk of undesirable side effects. Conventional singlelayered matrix tablets have been extensively utilized to deliver APIs into the body. However, these conventional single-layered matrix tablets present suboptimal delivery properties, such as non-linear drug delivery profiles which may cause higher side effects. Recently, a multi-layered technology has been developed to overcome or eliminate the limitations of the singlelayered tablet with more flexibility. This technology can give a good opportunity in formulating new products and help pharmaceutical companies enhancing their life cycle management. In this review, a brief overview on the multi-layered tablets is given focusing on the various tablet designs, manufacturing issues and drug release profiles.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.326-330
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• 2010

A laser based needle-free liquid drug injection device has been developed. A laser beam is focused inside the liquid contained in the rubber chamber of micro scale. The focused laser beam causes explosive bubble growth, and the sudden volume increase in a sealed chamber drives a microjet of liquid drug through the micronozzle. The exit diameter of a nozzle is 125 ${\mu}m$ and the injected microjet reaches an average velocity of 264 m/s. This device adds the time-varying feature of microjet to the current state of liquid injection for drug delivery.