• Journal of Pharmaceutical Investigation
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• 제30권3호
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• pp.207-211
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• 2000

The objective of this work is to investigate the effect of molecular weight of poly(ethylene oxide) (PEO) and release medium on the release of nifedipine (NP) from PEO tablets containing NP and to get some mechanistic insights into the release of NP. The tablets containing NP were prepared by direct compression, using a flat-faced punch and die. The molecular weights of PEOs used were 200K, 900K, 2000K and 7,000K. The release kinetics were studied for 24 hours in aqueous ethanol solution, using a dissolution tester at $36.5^{\circ}C$ and 100 rpm. Drug release rate increased, as the concentration of ethanol in the dissolution medium increased, due to the increased solubility of NP. As the molecular weight of PEO increased, release rate decreased, due to the slower swelling and dissolution of PEO. The power values obtained by fitting data to the power law expression $(M_t/M_{\infty}=kt^n)$ indicated that, at low ethanol concentration, the release of NP is governed by anomalous diffusion. However, as the ethanol concentration increases, diffusional release becomes to prevail over anomalous or zero-order release. Overall, these results provided some insights into the release of NP from PEO tablet.

• Journal of Pharmaceutical Investigation
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• 제24권3호spc1호
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• pp.33-39
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• 1994

We have studied the effect of loading amount and particle size on the rate of release of 5-fluorouracil (5-FU) from ethylene-vinyl acetate (EVA) matrix. Release rate increased as the loading amount and particle size increase. We also studied the effect of additives (lactose and algin) on the rate of release of 5-FU. Both algin and lactose promoted the rate of release. The ability to increase the rate is in the order of algin>lactose>5-FU. Scanning electron microscope study clearly shows that large cavities and cracks are created. The results imply that, by the proper combinations of the amount of the additive, $EVA_c$ and drug, the rate of drug release can be modulated over a wide range of values.

• Journal of Pharmaceutical Investigation
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• 제22권4호
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• pp.323-326
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• 1992

$Poly({\varepsilon}-carbobenzoxy\;L-lysine)/poly(ethylene oxide)/poly({\varepsilon}-carbobenzoxy\;L-lysine)$ (LEL) block copolymers containing $poly({\varepsilon}-carbobenzoxy\;L-lysine)$ (PCLL) as the A component and poly(ethylene oxide) (PEO) as the B component were investigated as drug delivery matrix. PCLL homopolymer and LEL block copolymer microspheres containing anticancer drug, cytarabine, were prepared by a solvent evaporation process and the release patterns of cytarabine from the microspheres were investigated in vitro. The size of PCLL homopolymer and LEL block copolymer microspheres was ranged from $0.2\;{\mu}m$ to $1\;{\mu}m$ in diameter and the shape of the microspheres was almost round. The release pattern of cytarabine from the block copolymer microspheres was dependent on the mole % of PEO of the block copolymers.

• Journal of Ginseng Research
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• 제14권2호
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• pp.122-125
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• 1990

Ethylene was released from leaf and fruit but root of Panax ginseng. Root callus showed higher ethylene release (ER) than fruit ER increased with leaf senesence. Fruit during ripening showed decreasing ER in the order of green stage, early stage of reddening and fully ripened stage. between leaves from the plant with fruits in different stages of ripening showed similar trend of fruit in ER but it was about 10 times higher in leaves than in fruits. Leaves of P. quinquefolius showed about 200 times higher ER than that of P ginseng on 22 July Fruits from the plant treated with ethephon showed higher ER after 109 days. Forty-five day-old seedlings grown with various growth regulators showed a significant decrease of stem length and significant increase of ER only in Uniconazole (0.1 ppm) and H-9 (0.0, 5 ppm) solution.

• Journal of Pharmaceutical Investigation
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• 제26권4호
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• pp.281-289
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• 1996

In our previous work, we have studied the effect of lactose and sodium alginate (SA) on the rate of release of 5-fluorouracil (5-FU) from ethylene-vinyl acetate (EVA) matrix. These hydrophilic additives promoted the rate of 5-FU release and the increase in rate was larger when SA was used. Both additives showed better ability to increase the rate than 5-FU itself. In this paper, we extended our study to another hydrophilic additive, Carbopol 940 (CP). Compared to SA or lactose, CP increased the rate of 5-FU release markedly. Release rate increased as the loading amount and the pH of the release medium increased. After release experiment, matrix volume increased up to 15 times of that before release experiment, depending on the amount of CP dispersed in the matrix and the pH of the release medium. On the other hand, the volume of the matrix containing lactose or SA decreased. The weight changes of the dry matrix before and after release experiment imply that CP is not released out of the matrix, to the contrary of lactose and SA. Scanning electron microscope study clearly showed that large cavities and pores are generated on the surface and the inside of the matrix. These results indicate that the mechanism by which CP increases the release rate is quite different from that of monomeric additives such as lactose or SA.

• 폴리머
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• 제29권6호
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• pp.593-598
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• 2005

Layer-by-layer(LbL) 자기 조립법에 의한 poly(ethylene-alt-maleic anhydride)(PEMAh)/poly(4-vinyl pyridine)(P4VP) 다층막의 염료 흡착 거동 및 pH 변화에 의한 염료 방출 거동을 Rodamine 6G(R6G)를 지시제로 사용하여 조사하였다. UV-vis 분광 분석을 이용하여 (PEMAh/P4VP)n 다층막의 두께 및 R6G의 흡착 및 방출 거동을 조사하였다. 다층막에 흡착되는 R6G의 흡착량은 필름의 두께 증가에 따라 선형적으로 증가하였다. (PEMAhAh/P4VP)n 다층막의 투과성은 pH 조건에 민감한 거동을 보였으며, 방출액의 pH가 감소할수록 R6G 방출 속도와 방출량은 증가하였다. PEMAh/poly(ethyleneimine)(PEI) capping layer를 (PEMAh/P4VP)n 다층막에 추가로 적층함으로써 흡착된 R6G의 방출 속도를 조절할 수 있었다.

• Archives of Pharmacal Research
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• 제24권1호
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• pp.69-73
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• 2001

Biodegradable hydrogels based on glycidyl methacrylate dextran (CMD) and dimethacrylate poly(ethylene glycol) (DMP) were proposed for colon-specific drug delivery. GMD was synthesized by coupling of glycidyl methacylate with dextran in the presence of 4-(N, N-dimethylamino)pyridine (DMAP) using dimethylsulfoxide as a solvent. Methacrylate-terminated poly (ethylene glycol) (PEG) macromer was prepared by the reaction of PEG with methacryloyl chloride. CMD/DMP hydrogels were prepared by radical polymerization of phosphate buffer solution (0.1 M, pH 7.4) of GMD and DMP using ammonium peroxydisulfate (APS) and UV as initiating system. The synthetic GMD, DMP and GMD/DMP hydrogels were characterized by fourier transform infrared (FT-lR) spectroscopy. The FITC-albumin loaded hydrogels were prepared by adding FITC-albumin solution before UV irradiation. Swelling capacity of GMD/DMP hydrogels was controlled not only by molecular weight of dextran, but also by incorporation ratio of DMP Degradation of the hydrogels has been studied in vitro with dextranase. FITC-albumin release from the GMD/DMP hydrogels was affected by molecular weight of nextran and the presence of dextranase in the release medium.

• Journal of Pharmaceutical Investigation
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• 제41권6호
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• pp.347-354
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• 2011

Repeated oral administration of loxoprofen can induce many side effects such as gastric disturbances and acidosis. Therefore, we considered alternative routes of administration for loxoprofen to avoid such adverse effects. The aim of this study was to develop an ethylene-vinyl acetate (EVA) matrix system containing a permeation enhancer for enhanced transdermal delivery of loxoprofen. The EVA matrix containing loxoprofen was fabricated and the effects of drug concentration, temperature, enhancer and plasticizer on drug release were studied from the loxoprofen-EVA matrix. The solubility of loxoprofen was highest at 40% (v/v) PEG 400. The release rate of drug from drug-EVA matrix increased with increased loading dose and temperature. The release rate was proportional to the square root of loading dose. The activation energy (Ea), which was measured from the slope of log P versus 1000/T, was 5.67 kcal/mol for a 2.0% loaded drug dose from the EVA matrix. Among the plasticizer used, diethyl phthalate showed the highest release rate of loxoprofen. Among the enhancers used, polyoxyethylene 2-oleyl ether showed the greatest enhancing effect. In conclusion, for the enhanced controlled transdermal delivery of loxoprofen, the application of the EVA matrix containing plasticizer and penetration enhancer could be useful in the development of a controlled drug delivery system.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.230.1-230.1
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• 2003

In case of oral application of quinupramine, antidepressants, it may cause adverse effects such as diarrhea, nausea due to transient high blood concentration. Ethylene vinyl acetate (EVA) which is heat-processible, flexible, inexpensive material was used for transdermal drug delivery. The purpose of this study was to develop the new transdermal delivery system of quinupramine using EVA polymer matrix that can provide sustained release and avoid the side effects. The EVA matrix containing quinupramine was prepared by solvent-evaporation method. (omitted)

• 한국응용과학기술학회지
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• 제28권4호
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• pp.410-417
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• 2011

Effects of ethylene-propylene diene monomer (EPDM)/polypropylene (PP), zinc oxide, stearic acid, and clay on the combustive properties based on EDPM/PP were investigated. The EDPM/PP/clay nanocomposites was compounded to prepare specimen for combustive analysis by cone calorimeter (ISO 5660-1). It was found that the specific mass loss rate (SMLR) in the nanocomposites decreased due to the fire resistance compared with unfilled EDPM/PP, while the nanocomposites showed the higher total heat release (THR), higher CO production release, and higher specific extinction area (SEA) than those of virgin EPDM/PP. The stearic acid for softening ruber increased the THR and amount of smoke by itself, combustible.