• 대한약학회:학술대회논문집
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• 대한약학회 2000년도 NEW STRATEGY FOR DRUG DEVELOPMENT IN POST-GENOMIC ERA(대한약학회)
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• pp.262.1-262.1
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• 2000

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.575-576
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• 2013

• 대한의용생체공학회:의공학회지
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• 제41권1호
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• pp.62-66
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• 2020

Controlled drug release is important for effective treatment of cancer. Poly(DL-lactide-co-glycolide) acid (PLGA) is a Food and Drug Administration (FDA) approved polymer and have been extensively studied as drug delivery carriers with biodegradable and biocompatible properties. However, PLGA drug delivery carriers are limited due to the initial burst release of drug. Certain drugs require an early rapid release, but in many cases the initial rapid release can be inefficient, reducing therapeutic effects and also increasing side effects. Therefore, sustained release is important for effective treatment. Poly Lactic Acid stereo complex (PLA SC) is resistant to hydrolysis and has high stability in aqueous solutions. Therefore, in this work, PLGA based discoidal polymeric particles are modified by Poly Lactic Acid stereocomplex (PLAsc DPPs). PLAsc DPPs are 3 ㎛ in diameter, also showing a relatively sustained release profile. Fluorescein 5(6)-isothiocyanate (FITC) released from PLAsc DPPs was continuously observed until 38 days, which showed the initial release of FITC from PLAsc DPPs was about 3.9-fold reduced as compared to PLGA based DPPs at 1 hour.

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3208-3212
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• 2012

Controlled drug delivery systems employing microparticles offer lots of advantages over conventional drug dosage formulations. Microencapsulation technique have been conducted with biodegradable polymers such as poly(lactic-co-glycolic acid) (PLGA) and poly(lactic acid) (PLA) for its adjustable biodegradability and biocompatibility. In this study, we evaluated two techniques, oil-in-water (o/w) emulsion solvent evaporation and spray drying, for preparation of polymeric microparticles encapsulating a newly synthesized drug, SS-AG20, for the long-term drug delivery of this low-molecular-weight drug with a very short half-life. Drug-loaded microparticles prepared by the solvent evaporation method showed a smoother morphology; however, relatively poor encapsulation efficiency and drastic initial burst were discovered as drawbacks. Spray-dried drug-loaded microparticles had an imperfect surface with pores and distorted portions so that its initial burst was critical (70.05-87.16%) when the preparation was carried out with a 5% polymeric solution. By increasing the concentration of the polymer, the morphology was refined and undesirable initial burst was circumvented (burst was reduced to 35.93-74.85%) while retaining high encapsulation efficiency. Moreover, by encapsulating the drug with various biodegradable polymers using the spray drying method, gradual and sustained drug release, for up to 2 weeks, was achieved.

• 청정기술
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• 제12권2호
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• pp.53-61
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• 2006

생분해성 고분자인 Poly(lactide-co-glycolide) (PLGA)와 약물 단백질로 약물 중합체를 만들기 위하여 초임계 나노 입자 제조 공정중 하나인 PGSS법을 이용하여 연구를 수행하였다. 초임계 이산화탄소에 의해서 고분자 PLGA의 유리전이온도($T_g$)를 강하시켜 가소화시키면서 단백질을 용기 내에서 혼합하였다. 고분자 PLGA에 캡슐화 된 단백질의 입자를 얻기 위해 고압 용기에 들어있는 시료를 노즐을 통하여 대기압으로 이산화탄소를 분사시켰다. 입자의 형태, 입자 크기 그리고 크기 분포에 대한 영향을 알아보기 위해서 고압 용기 안에서 초임계 이산화탄소를 이용하여 공정변수들을 조작함으로서 PGSS 실험을 하였다. 입자는 거칠고 불규칙하며 표면에 기공이 생성되었음을 확인하였다. 제조된 입자의 크기와 크기분포는 과포화도, 핵 생성시간 등으로 설명하였다. 제조된 입자 내의 protein의 활성도 저하는 거의 없었다.

• Journal of Pharmaceutical Investigation
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• 제29권4호
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• pp.315-321
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• 1999

Poly (lactide-co-glycolide) (PLGA) microspheres containing ovalbumin (OVA) as a model protein drug were prepared by double emulsification method, and various conditions such as mixing rate, volume of outer phase and isopropyl alcohol concentration in outer phase during secondary emulsification were observed to control the size of microspheres. In addition, entrapment efficiency of OVA and protein denaturation were also evaluated. As the rate of stirring was increased, the size of particles was decreased. But excessive stirring increased the particle size of microspheres. In a preparation condition of small volume of outer phase, the particle size was decreased but the entrapment efficiency was increased. Adding isopropyl alcohol to outer phase decreased the size of particles, but increased the entrapment efficiency. Microparticles should have smaller size than $10\;{\mu}m$ to be uptaked by Peyer's patch in small intestine. High speed of mixing and relatively small volume of outer phase are needed to reduce the size. In addition, appropriate amount of isopropyl alcohol in outer phase also plays an important role in size reduction of PLGA microspheres.

• Macromolecular Research
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• 제14권4호
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• pp.461-465
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• 2006

Two types of injectable system using thermosensitive chitosan (chitosan-g-NIPAAm), hydrogel and microparticles (MPs)-embedded hydrogel were developed as drug carriers for controlled release and their pharmaceutical potentials were investigated. 5-Fluorouracil (5-FU)-loaded, biodegradable PLGA MPs were prepared by a double emulsion method and then simply mixed with an aqueous solution of thermosensitive chitosan at room temperature. All 5-FU release rates from the hydrogel matrix were faster than bovine serum albumin (BSA), possibly due to the difference in the molecular weight of the drugs. The 5-FU release profile from MPs-embedded hydrogel was shown to reduce the burst effect and exhibit nearly zero-order release behavior from the beginning of each initial stage. Thus, these MPs-embedded hydrogels, as well as thermosensitive chitosan hydrogel, have promising potential as an injectable drug carrier for pharmaceutical applications.

• Archives of Pharmacal Research
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• 제27권1호
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• pp.1-12
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• 2004

Initial burst is one of the major challenges in protein-encapsulated microparticle systems. Since protein release during the initial stage depends mostly on the diffusional escape of the protein, major approaches to prevent the initial burst have focused on efficient encapsulation of the protein within the microparticles. For this reason, control of encapsulation efficiency and the extent of initial burst are based on common formulation parameters. The present article provides a literature review of the formulation parameters that are known to influence the two properties in the emulsion-solvent evaporation/extraction method. Physical and chemical properties of encapsulating polymers, solvent systems, polymer-drug interactions, and properties of the continuous phase are some of the influential variables. Most parameters affect encapsulation efficiency and initial burst by modifying solidification rate of the dispersed phase. In order to prevent many unfavorable events such as pore formation, drug loss, and drug migration that occur while the dispersed phase is in the semi-solid state, it is important to understand and optimize these variables.

• 폴리머
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• 제33권4호
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• pp.353-357
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• 2009

분무건조는 약물의 입자 제조에 널리 사용되고 있는 효과적이고 안정적인 공정 중 하나이다. 과거 분무건조의 방법에서는 입자의 응집을 조절하기 쉽지 않았으며, 크기 조절에도 많은 어려움을 겪어 왔다. 특히 고분자 입자의 제조는 저분자 유기물질인 식품, 의약원료 등과 비교하여 상대적으로 제조하기 어려운 면이 있었다. 본 연구에서는 기존의 분무건조기를 개조하여 노즐에 전기장을 외부에서 가해 줌과 동시에 동축 이중 노즐을 사용하여 고분자 입자의 제조를 시도하였다. 내부 고분자 물질로는 폴리에틸렌글리콜과 폴리락타이드코글리코라이드를, 외부 물질로는 락토오스를 사용하였다. 그 결과 전기장을 사용하지 않는 분무건조에 비해 비교적 일정한 크기와 모양을 제조할 수 있었으며, 입자 간의 응집을 줄일 수 있음을 확인하였다. 전기분무건조된 PLGA 분말은 주로 $2{\sim}5{\mu}m$ 기인 둥근 모양의 입자로 구성되었다.