• Macromolecular Research
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• v.9 no.5
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• pp.277-284
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• 2001

Poly(exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride)s [poly(ETA)s] and poly($\alpha$-ethoxy-exo-3,6-epoxy-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil)s [poly(EETFU)s ] with various average molecular weights were prepared by photopolymerizations. The number average molecular weights of the fractionated poly(ETA)s and poly(EETFU)s determined by GPC were in the range of 3,600∼21,000 and 3,600-33,400, respectively. The release rate of 5-FU from poly(EETFU) decreased with increasing average molecular weight. The in vitro cytotoxicity of poly(ETA) against a normal cell line was lower than that of 5-fluorouracil(5-FU), The in vivo antitumor activities of the synthesized samples at dosage of 0.8 mg/kg against mice bearing sarcoma 180 tumor cell line decreased in the following order: poly(EETFU) > poly(ETA) > EETFU > ETA > 5-FU. The antiangiogenic activities of the poly(ETA)s were better than those of 5-FU.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.2
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• pp.101-109
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• 2004

In this study, the solid-liquid separation characteristics of swine wastewater were investigated for the coagulation and dissolved air flotation (DAF). Coagulation characteristics were studied using jar-tester with the different coagulants and dosage amounts. DAF characteristics were also investigated in terms of the different flotation conditions with the raw swine wastewater, pH adjustment only, and adding coagulants. When the raw swine wastewater was coagulated with the only inorganic coagulants, the proper inorganic coagulants were founded as $FeCl_3$ > PAC > Alum orderly, and the optimal coagulant dosages were founded as $1,000mg/{\ell}$, $1,500mg/{\ell}$, $1,500mg/{\ell}$, respectively. As the raw swine wastewater was treated with the polymer coagulants, the only cationic polymer coagulant showed an effective coagulation and the optimal dosage of cationic coagulant was founded as $200mg/{\ell}$. When the different dosages of cationic polymer was added to each $500mg/{\ell}$ of the inorganic coagulants, the proper inorganic coagulants were founded as $FeCl_3$ > Alum > PAC orderly, and optimal cationic polymer dosages was founded as $25mg/{\ell}$, $25mg/{\ell}$, and $100mg/{\ell}$, respectively. Resulting from the raw swine wastewater experiments using DAF without coagulation, the proper operation conditions of DAF were set to 400% of recycling ratio, 4 atm in air dissolving tank, and under pH 3. But the raw swine wastewater was difficult to successfully operate DAF without pre-coagulation. While the DAF separation after pre-coagulation using inorganic coagulants was not accomplished due to the low intensity of the floc, DAF after pre-coagulation using both the inorganic and cationic polymer coagulants was accomplished very well. Optimal dosage of cationic polymer coagulant in case of $500mg/{\ell}$ Alum dosage was founded as $500mg/{\ell}$.

• Advanced Composite Materials
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• v.16 no.4
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• pp.315-334
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• 2007

In the present study, chopped henequen natural fibers without and with surface modification by electron beam (E-beam) treatment were incorporated into a polypropylene matrix. Prior to composite fabrication, a bundle of raw henequen fibers were treated at various E-beam intensities from 10 kGy to 500 kGy. The effect of E-beam intensity on the interfacial, mechanical and thermal properties of randomly oriented henequen/polypropylene composites with the fiber contents of 40 vol% was investigated focusing on the interfacial shear strength, flexural and tensile properties, dynamic mechanical properties, thermal stability, and fracture behavior. Each characteristic of the material strongly depended on the E-beam intensity irradiated, showing an increasing or decreasing effect. The present study demonstrates that henequen fiber surfaces can be modified successfully with an appropriate dosage of electron beam and use of a low E-beam intensity of 10 kGy results in the improvement of the interfacial properties, flexural properties, tensile properties, dynamic mechanical properties and thermal stability of henequen/polypropylene composites.

• Journal of Pharmaceutical Investigation
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• v.34 no.4
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• pp.289-297
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• 2004

Acyclovir (ACV) is one of the most effective and selective agents against viruses of the herpes group. Because of low solubility, bioavailability of ACV has shown below 30% with oral dosage form. In our previous study, we reported that the fabrication of solid dispersion of ACV was possible and the solid dispersion of ACV and PVP was the most useful in all samples. In this study, we examined the effect of mixture ratio of polymers (PEG and PVP) to ACV. Solubility of ACV was dramatically increased up to 25 mg/ml in $80^{\circ}C$ distilled water. So water was used as a solvent to eliminate problem of residual solvent. Spray drying method was used for the solid dispersion of ACV as solvent extraction. Different scanning calorimeter was used to check degradation of drug. Polymer carriers were PEG 6,000 and PVP. In summary, ACV-PVP (1:3) showed the best solubility in distilled water.

• Journal of Pharmaceutical Investigation
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• v.36 no.2
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• pp.83-87
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• 2006

Poly(acrylic acid) (PAA) was identified to possess good mucoadhesive properties ensuring its application to extend the retention times of the formulations at the oral cavity, intended route of administration using the polymer. In the noncross-linked state, PAA will swell and become eroded owing to the presence of salivary flow from the site of application. The formation of cross-links between the polymer chains will allow swelling but prevents the erosion of the dosage form. In the current study, cross-linking was achieved by esterification of the PAA chains with sucrose. The density of crosslinking was modified by changing sucrose concentration and the duration of cure time. The cross-linking density of the polymer hydrogel was assessed by equilibrium swelling studies. The mucoadhesion testing method allowed a comparative study of the hydrogels prepared. An inverse relationship between equilibrium swelling and peak detachment force showed that increased PAA chain density per unit area enhanced the mucoadhesive interaction.

• Archives of Pharmacal Research
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• v.27 no.8
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• pp.878-883
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• 2004

Tacrolimus (FK506), which is isolated from Streptomyces tsukubaensis, is a new potent immu-nosuppressant. Because of poor solubility in water, the conventional intravenous dosage forms of tacrolimus contain surfactants such as cremophor EL (BASF Wyandotte Co.) or hydroge-nated polyoxy 60 castor oil (HCO-60) which may cause adverse effects. This study relates to a polymer-tacrolimus conjugate, which can be dissolved in water, formed by chemically binding the sparingly soluble drug, tacrolimus, with the water soluble polymer, methoxypoly(ethylene glycol) (mPEG). Water soluble tacrolimus-mPEG conjugates have been synthesized and shown to be function in vitro as prodrugs. These conjugates are in the form of an ester wherein the 24-, 32- or 24,32-positions are esterified. The desired 24-, 32- or 24,32-esterified com-pounds were obtained by initially acylating of tacrolimus with iodoacetic acid at the 24-,32-, or 24,32-positions and then reacting the resulting acylated tacrolimus with a mPEG in the pres-ence of a base such as sodium bicarbonate. These conjugates were converted again into tac-rolimus by the action of enzymes in human liver homogenate, and the half-lives of the conjugates are approximately 10 min in the homogenate, indicating that the esterified tacroli-mus derivatives may be practically applicable as a prod rug for the immunosuppressant.

• Polymer(Korea)
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• v.31 no.3
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• pp.269-272
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• 2007

In this study, we investigated the effects of electron beam irradiation on the rheological properties of PLA for enhancing processability. The electron beam was irradiated onto the pure PLA, chemically modified PLA by reactive extrusion, and PLA containing functional monomer. The complex viscosity and log G'vs. log G" plot among dynamic rheological properties were chosen for comparison. The complex viscosity of irradiated pure and chemically modified PLA decreased significantly due to de-gradation of PLA molecules with increasing the E-beam dosages. Complex viscosity of irradiated PLA with functional monomer showed maximum value at moderate dosage, while at high dosage the complex viscosity was decreased by a prolonged irradiation.

• Journal of Pharmaceutical Investigation
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• v.30 no.3
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• pp.179-189
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• 2000

Clebopride malate(Cm) is a new benzamide drug which has a potent central antidopaminergic activity possessing antiemetic and anxiolytic properties. A purpose of this study was to assess the feasibility of formulating sustained release preparation by dispersing a drug in hydrophilic polymeric matrices and double layered tablets(DLT), using HPMC, carbopol, PEO, PVP/VA and other polymers as a rate controlling barrier. The matrix and DLT showed optimum dissolution pattern up to 8 hours and the contents of polymer were optimized at 30% level in this preparation. After an oral administration in beagle dog, Cm concentration was determined by use of GC-ECD and pharmacokinetic parameters were calculated by Vallner's method. The AUC of DLT showed similar results and the duration of action was increased 55% compared to that of regular release dosage form. The calculated absorption rate effectiveness(ARE) and controlled release effectiveness(CRE) for DLT increased 50% compared to that of matrix, the overall effectiveness(E) of this product appears to be about 70%. in vivo effectiveness test, DLT showed significant differences from control on antiemetic action of Cm. In consequence, it was possible to conclude that double layered tablet might be a good candidate for the sustained release dosage forms.

• Journal of Pharmaceutical Investigation
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• v.32 no.4
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• pp.327-330
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• 2002

Alginate based polymeric matrices were designed for controlled release and stabilization of cefaclor in gastrointestinal fluid. Cefaclor is known to be acid stable and subjected to be degraded at neutral and alkaline pHs. In order to achieve an effective release profile of cefaclor in gastrointestinal tract, a particular strategy in dosage form design should be required from the view point of maintaining its activity. The amphiphilic nature of cefaclor allowed its controlled release using ionic polymers based on ionic interaction between the drug and polymers. The thrust of this study was to develop a technique that delivers cefaclor keeping effective release rate in the intestinal tract. Considering the fast degradation of cefaclor in the intestinal fluid, the matrices were designed to release surplus amount of cefaclor. The alginate based matrices demonstrated increase in release rate in the simulated intestinal fluid, which was favorable to compensate the degraded portion of cefaclor. In addition, stabilization of cefaclor in the intestinal fluid was obtained by employing citric acid that provides an local acidic environment. The matrices might be valuably used for the development of an oral cefaclor dosage form.

• Journal of the Korean Ceramic Society
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• v.55 no.2
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• pp.126-134
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• 2018

Using aqueous solution free radical polymerization with glacial acrylic acid (GAA), maleic anhydride (MA) and sodium methallyl disulfonate (SMADS), a novel linear polycarboxylate dispersant was synthesized for ceramics. Dispersant linear structural characterization was done by FTIR, $^1H$ NMR, HPLC and GPC, and the ratio of monomers was determined using an orthogonal experiment. This research is focused on the effects of polymerization temperature, monomer mole ratios and dosage of initiator on ceramic slurry viscosity with linear polycarboxylate dispersant for ceramic dosage rate of 0.30% (based on dry slurry), all of which were investigated by single factor test. The best polymerization conditions for linear GAA-MA-SMADS are when n(AA) : n(MA) : n(SMADS) equals 3.0 : 1.0 : 0.5, the molecular weight of the polymer is 4600 daltons, the initiator sodium persulfate accounts for 7% of the total mass of polymerized monomers, the polymerization temperature is $90^{\circ}C$ and the reaction time is 2 h. The ceramic body slurry viscosity drops from $820mPa{\cdot}s$ to $46mPa{\cdot}s$ when the concentration of the polycarboxylate dispersant is 0.30%.