• Macromolecular Research
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• 제13권4호
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• pp.327-333
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• 2005

pH-sensitive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing it in the small intestine. In this study, hydrogels based on poly(ethylene oxide) (PEO) networks grafted with methacrylic acid (MAA) or acrylic acid (AAc) were prepared via a two-step process. PEO hydrogels were prepared by ${\gamma}-ray $ irradiation (radiation dose: 50 kGy, dose rate: 7.66 kGy/h), grafted by either MAA or AAc monomers onto the PEO hydrogels and finally underwent irradiation (radiation dose: 520 kGy, dose rate: 2.15 kGy/h). These grafted hydrogels showed a pH-sensitive swelling behavior. The grafted hydrogels were used as a carrier for the drug delivery systems for the controlled release of insulin. Drug-loaded hydrogels were placed in simulated gastric fluid (SGF, pH 1.2) for 2 hr and then in simulated intestinal fluid (SIF, pH 6.8). The in vitro drug release behaviors of these hydrogels were examined by quantification analysis with a UV-Vis spectrophotometer.

• Journal of Pharmaceutical Investigation
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• 제34권4호
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• pp.275-281
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• 2004

We have studied the effect of polarity, current density, current duration, crosslinking density, swelling ratio, and permeation enhancers on the transdermal flux of ketoprofen from acrylamide hydrogel. Hydrogel was prepared by free radical crosslinking polymerization of acrylamide. Drug loading was made just before transport experiment by soaking the hydrogel in solution containing drug. In vitro flux study using hairless mouse skin was performed at $36.5^{\circ}C$ using side-by-side diffusion cell, and the drug was analysed using HPLC/UV system. The result showed that, compared to passive flux, the total amount of drug transported increased about 18 folds by the application of $0.4\;mA/cm^2$ cathodal current. Anodal delivery with same current density also increased the total amount of drug transported about 13 folds. It seemed that the increase in flux was due to the electrorepulsion and the increase in passive permeability of the skin by the current application. Flux increased as current density, the duration of current application and loading amount (swelling duration) increased. As the cross linking density of the hydrogel increased, flux clearly decreased. The effect of hydrophilic enhancers (urea, N-methyl pyrrolidone, Tween 20) and some hydrophobic enhancers (propylene glycol monolaurate and isopropyl myristate) was minimal. However, about 3 folds increase in flux was observed when 5% oleic acid was used. Overall, these results provide some useful information on the design of an optimized iontophoretic delivery system of ketoprofen.

• 한국정밀공학회지
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• 제28권12호
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• pp.1347-1352
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• 2011

Recently, as the aged population grows around the world, many medical instruments, devices, and their fabrication processes are developing. Among the devices, a drug delivery stent is a good example for precision machining. Conventional drug delivery stent has problem of the remaining polymer because the drug is coated on the surface with it. If the drug is impregnated into the micro hole array on the stent surface, the polymer can be perfectly eliminated. Micro sized holes are generally fabricated by laser machining however, the fabricated holes do not have an enough aspect ratio to contain the drug or a good surface finish to deliver the stend to blood vessel tissue. To overcome these problems, we propose a vibration-assisted machining mechanism with PZT (Piezoelectric Transducers) for abrication of micro sized holes better. The results indicated that the burr size can be significantly decreased with vibration assisted in nanosecond pulse laser drilling test.

• Archives of Pharmacal Research
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• 제25권4호
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• pp.397-415
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• 2002

This paper deals with a crucial mechanism for interaction of basic drugs and cardiac glycosides at the hepatic uptake level. Available literature data is provided and new material is presented to picture the differential transport inhibition of bulky (type2) cationic drugs by a number of cardiac glycosides in rat liver. It is shown that the so called organic anion transporting peptide 2 (oatp2) is the likely interaction site: differential inhibition patterns as observed in oocytes expressing oatp2, could be clearly identified also in isolated rat hepatocytes, isolated perfused rat liver and the rat in vivo. The anticipation of transport interactions at the hepatic clearance level should be based on data on the relative affinities of interacting substrates for the transport systems involved along with knowledge on the pharmacokinetics of these agents as well as the chosen dose regimen in the studied species. This review highlights the importance of multispecific tranporter systems such as OATP, accommodating a broad spectrum of organic compounds of various charge, implying potential transport interactions that can affect body distribution and organ clearance.

• KSBB Journal
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• 제14권3호
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• pp.297-302
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• 1999

Poly(DL-lactide)로 피막된 고분자 매트릭스를 약물전달시스템에 이용하기 위해 키토산, 키토산 염산염 및 술폰화 키토산으로 제조되었다. 모델 약물로 프레드니솔론을 사용하는 본 약물방출에 관한 연구는 pH 1.2 염산 용액에서 실험을 하였다. 약물 방출 속도는 고분자 매트릭스의 함유량이 증가할 수록 감소하였다. 피막된 고분자 매트릭스의 종류에 따라 지연된 약물의 방출시간은 키토산의 경우가 가장 길었으며, 술폰화 키토산, 키토산 염산염의 순서였다. DL-PLA로 피막된 고분자 매트릭스가 피막되지 않는 고분자 매트릭스 보다 약물 방출시간이 2배 정도의 지연되었을 뿐만 아니라 초기에 약물 과잉방출 현상도 작아 피막된 경우가 방출 조절형 제재로서 더 바람직한 결과를 보였다. 따라서 DL-PLA로 피막된 고분자 매트릭스는 장시간의 약물 방출을 위한 약물전달체로써의 응용이 기대된다.

• Archives of Pharmacal Research
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• 제28권6호
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• pp.722-729
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• 2005

With the aim to improve the specificity and to reduce the cytotoxicity of polyethylenimine (PEI), we have synthesized the conjugates of the branched PEI (25 kDa) with transferrin. The trans-ferrin-PEI (TP) conjugates with five compositions were synthesized using periodate oxidation method and confirmed by FT-IR spectroscopy and gel permeation chromatography. The free amine contents of TP conjugates, which were able to condense and deliver DNA, increased as the amount of PEI increased. TP/DNA polyplexes were characterized by measuring gel elec-trophoresis, ethidium bromide fluorescence quenching, particle size and zeta potential of complexes. Complete complexation of the polyplexes was observed above the N/P ratio of 5 in TP/DNA, and above 3 in PEI/DNA, respectively. The zeta potential of the complexes decreased as the amount of transferrin in TP conjugates increased. Transfection efficiency of TP conjugates was evaluated in HeLa cell and Jurkat cell systems. Among the five compositions of TP conjugates, TP-2 system mediated a higher $\beta$-galactosidase gene expression than PEI system in Jurkat cell which was known to express elevated numbers of transferrin receptors. From the results of the cell viability based on MTT assay, TP conjugates showed lower cytotoxicity com-pared with the PEI system. We expect that the TP conjugate can be used efficiently as a non-viral gene delivery vector.

• Journal of Korean Neurosurgical Society
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• 제61권3호
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• pp.343-351
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• 2018

Diffuse intrinsic pontine glioma (DIPG) is a deadly paediatric brain cancer. Transient response to radiation, ineffective chemotherapeutic agents and aggressive biology result in rapid progression of symptoms and a dismal prognosis. Increased availability of tumour tissue has enabled the identification of histone gene aberrations, genetic driver mutations and methylation changes, which have resulted in molecular and phenotypic subgrouping. However, many of the underlying mechanisms of DIPG oncogenesis remain unexplained. It is hoped that more representative in vitro and preclinical models-using both xenografted material and genetically engineered mice-will enable the development of novel chemotherapeutic agents and strategies for targeted drug delivery. This review provides a clinical overview of DIPG, the barriers to progress in developing effective treatment, updates on drug development and preclinical models, and an introduction to new technologies aimed at enhancing drug delivery.

• Journal of Pharmaceutical Investigation
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• 제39권1호
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• pp.13-18
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• 2009

Docetaxel is an anticancer agent with low aqueous solubility. More extensive clinical use of this drug is somewhat delayed due to lack of appropriate delivery vehicles. An attempt was made to adopt an o/w emulsion as the drug carrier which incorporated docetaxel in the propyleneglycerol stabilized by a mixed-emulsifier system. A suitable formulation was found in this study: 10 mg/mL docetaxel, 10% (w/v) oil blend, 4% (w/v) PG, 3% (w/v) Solutol HS 15 in 2.25% (w/v) glycerol solution. The formulated emulsion has very good stability when stored at $40^{\cird}C$, and the docetaxel containment efficiency can be maintained above 95% and the mean emulsion diameter around $10{\mu}m$ for at least 3 months. The formulated emulsion is a promising carrier for docetaxel and other lipophilic drugs.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2007년도 추계학술대회
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• pp.59-62
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• 2007

The basic concept and preliminary performance results of a miniaturized electroosmotic (EO) pump with diaphragms were included in the present study. The separation of an electroosmotic pumping liquid from a drug using diaphragms is mainly to have a freedom in choosing an electroosmotic pumping liquid and to achieve the optimal drug delivery, and, preferably its precise control. We performed maximum flow rate, maximum pressure, and maximum current measurements with and without diaphragm designs. As a result, the effect of diaphragms on pump performance at the maximum condition is small. However, the presence of diaphragms does not allow indefinite continuous pumping.

• Biomolecules & Therapeutics
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• 제21권6호
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• pp.423-434
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• 2013

The adoption of oligonucleotide aptamer is well on the rise, serving an ever increasing demand for versatility in biomedical field. Through the SELEX (Systematic Evolution of Ligands by EXponential enrichment), aptamer that can bind to specific target with high affinity and specificity can be obtained. Aptamers are single-stranded nucleic acid molecules that can fold into complex three-dimensional structures, forming binding pockets and clefts for the specific recognition and tight binding of any given molecular target. Recently, aptamers have attracted much attention because they not only have all of the advantages of antibodies, but also have unique merits such as thermal stability, ease of synthesis, reversibility, and little immunogenicity. The advent of novel technologies is revolutionizing aptamer applications. Aptamers can be easily modified by various chemical reactions to introduce functional groups and/or nucleotide extensions. They can also be conjugated to therapeutic molecules such as drugs, drug containing carriers, toxins, or photosensitizers. Here, we discuss new SELEX strategies and stabilization methods as well as applications in drug delivery and molecular imaging.