초록 ▼

항암제처럼 생리활성이 강한 화합물을 생체내에 투여 하였을 경우에는 전신에 약물이 확산되어 극심한 부작용을 유발하거나 정상세포와 조직을 크게 손상시키는 심각한 문제점이 있다. 따라서 본 연구에서는 항암제를 알부민 미립구에 봉입하여 간 표적용 약물수송체의 개발 및 그 이용 가능성을 평가하였다. 여러 제조 조건에서 약물이 봉입된 혈청 알부민 미립구를 제조하고 이 약물수송체를 치료에 응용하기 위하여 필요한 아래의 실험을 행하였다.
제조된 알부민 미립구의 형태, 표면의 성질, 크기 분포를 관찰하였으며, 약물의 봉입효율, in vit

항암제처럼 생리활성이 강한 화합물을 생체내에 투여 하였을 경우에는 전신에 약물이 확산되어 극심한 부작용을 유발하거나 정상세포와 조직을 크게 손상시키는 심각한 문제점이 있다. 따라서 본 연구에서는 항암제를 알부민 미립구에 봉입하여 간 표적용 약물수송체의 개발 및 그 이용 가능성을 평가하였다. 여러 제조 조건에서 약물이 봉입된 혈청 알부민 미립구를 제조하고 이 약물수송체를 치료에 응용하기 위하여 필요한 아래의 실험을 행하였다.
제조된 알부민 미립구의 형태, 표면의 성질, 크기 분포를 관찰하였으며, 약물의 봉입효율, in vitno에서의 약물방출 양식등을 검토하였다. 또한 약물을 함유한 알부민 미립구가 실험동물의 체내에서 각 장기에 분포되는 정도를 측정한 후 간에서의 소실속도를 측정하였다.
혈청 알부민 미립구는 구형이며, 표면은 매끄럽고 치밀하다. 제조조건에 따라 입자도의 분포는 달라지나 대부분의 미립구는 망상세포에 내포될 수 있는 정도의 크기로 만들어 진다. In vitro 에서 항암제의 방출양식은 처음 10분 동안 미립구의 표면근처에 있는 약물이 방출되어 (burst was affect)가 나타나고 장시간 동안 서서히 지속적으로 방출된다. 방출정도와 속도는 제조조건에 따라 조절이 가능하다. 또한 단백분해 효소에 의하여 알부민 미립구의 기질이 분해되어 약물이 방출되는 속도도 조절이 가능하다.
99mTc로 표지화된 알부민 미립구를 토끼에 정맥주사 하였을때 망상세포가 많이 분포되어 있는 간에 집중적으로 축적되었다. ?H 로 표지화한 adriamycin을 봉입시킨 인 혈청 알부민 미립구를 흰쥐에 주사하여 간에서의 adriamycin의 농도를 시간에 따라 측정하여 adriamycin의 지속적인 방출을 검토하였다. 알부민 미립구에 봉입된 adriamycin은 약 60-70%가 간에 선택적으로 수송되었으며 4-8주 이상 지속적인 방출을 거쳐서 소실되었다. 8주후 심장조직을 현미경으로 관찰하였을때 병리조직학적 변화가 없었다. 이상의 연구 결과로 상용량보다 훨씬 적은 용량을 월 1회정도 투여하여 타 장기에 부작용을 일으키지 않고 우수한 간암치료 효과를 얻을 수 있는 약물 수송체의 개발이 가능하다고 사료된다.

Abstract ▼

In attempt to develop a drug delivery system using serum albumin microspheres, bovine serum albumin microspheres containing antitumor agent, cyta abine, were prepared by using the method of thermal denaturation and using the cross-linking agent, formaldehyde. The shape, surface characteristics, siz

In attempt to develop a drug delivery system using serum albumin microspheres, bovine serum albumin microspheres containing antitumor agent, cyta abine, were prepared by using the method of thermal denaturation and using the cross-linking agent, formaldehyde. The shape, surface characteristics, size distribution, behavior of in vivo distribution, drug release behavior, and degradation of albumin microspheres in animal liver tissue homogenate and proteolytic enzyme were investigated. The shape of albumin microspheres was spherical and the surface was smooth and compact. The size distribution of the albumin microspheres was affected by dispersion forces during emulsification and albumin concentration. Distribution of albumin microspheres after intravenous administration in rabbit was achieved immediately. In vitro, albumin microsphere matrix was so hard that it retained most of cytarabine except initial burst during the first 10 minutes, and the level of drug release during the initial burst was affected by heating temperature or amount of cross-linking agent, drug/albumin concentration ratio and size distribution. After drug release test, the morphology of albumin microspheres was not changed. Albumin microsphere matrix was degraded by the rabbit liver tissue homogenate and proteolytic enzyme. The degree of degradation was affected by heating temperature or cross-linking degree. In attempt to localize the adriamycin to the liver and maintain the effective concentration in it, adriamycin-entrapped HSA microspheres were prepared and investigated by the various in vitro and in vivo experiments. The shape, surface characteristics and size distribution of HSA a crosphere were observed by scanning electron microscopy. The in vitro drug release, albumin matrix degradation by protease, in vivo uptake and elimination of HSA microspheres were studied. About 1 day after i.v. injection, the concentration of drug in the liver is the highest. About after 6 weeks the radioactivity in the liver decrease to the half of maximal radioactivity. More than 65% of the injected dose was found in the liver after i.v. injection. Adriamycin-entrapped HAS microspheres were phagocytized and localized to the liver (50-60%) without cumulation in the heart and excreted at the show rate over several weeks. As shown in current results albumin microspheres with different physico-chemical properties may be prepared by controlling the condition of preparation. Specially controlled albumin microspheres seems to be an ideal drug delivery system which retains drug in the blood stream until microspheres are phagocytized by the specific target site and biodegraded by intrinsic porteolytic enzymes. And, drug can be localized in specific target site and continuously released.

목차 Contents

• Table of Contents...7
• 1. Physico-pharmaceutical characteristics of thermally denaturated albumin microspheres containing cytarabine....7
• 1.1. Introduction...7
• 1.2. Experimental method....11
• 1.2.1. Preparation of bovine serum albumin microspheres....11
• 1.2.2. Determination of morphology and size distribution....12
• 1.2.3. Determination of in vivo distribution of albumin microspheres atter I.V. administration in rabbit....12
• 1.2.4. Determination of drug release....13
• 1.2.5. Determination of matrix degradation in the animal liver tissue homegenate....13
• 1.2.6. Determination of matrix degradation in proteolytic enzyme....14
• 1.2.7. Determination of total amount of cytarabine entrapped in albumin microspheres....14
• 1.3. Results and discussion...15
• 1.3.1. Physicochemical properties....15
• 1.3.2. Size distribution....18
• 1.3.3. Determination of in vivo distribution of microspheres....22
• 1.3.4. Drug release behavior...22
• 1.3.5. Determination of matrix degradation in the animal liver tissue homogenate and proteolytic enzyme....28
• 1.4. Literature cited....34
• 2. Phycico-pharmaceutical study on the cross-linked albumin microspheres containing cytarabine....36
• 2.1. Introduction...36
• 2.2. Experimental method....37
• 2.2.1. Materials....37
• 2.2.2. Apparatus....37
• 2.2.3. Preparation of cross-linked albumin microspheres....37
• 2.2.4. Determination of morphology and size distribution....39
• 2.2.5. Determination of drug released....39
• 2.2.6. Determination of matrix degradation in proteolytic enzyme solution....40
• 2.3. Results and discussion...41
• 2.3.1. Physical shape and size distribution....41
• 2.3.2. Drug release and degradation begavior....41
• 2.4. Literature cited....54
• 3. Development of liver-targeting adriamycin Delivery system using humar seurm albumin microspheres....56
• 3.1. Introduction...56
• 3.2. Experimental methods....58
• 3.2.1. Materials....58
• 3.2.2. Apparatus....58
• 3.2.3. Experimental animals...59
• 3.2.4. Labeling of adriamycin with $^3H$....59
• 3.2.5. Proparation of HSA microspheres....63
• 3.2.6. Microscopic characterization and size determination of HSA microspheres....67
• 3.2.7. Measurement of adriamycin incorporation efficiency....69
• 3.2.8. In vitro release test....69
• 3.2.9. HSA matrix degradation by protease....70
• 3.2.10. Observation of liver tissue by TEM....71
• 3.2.11. Organ distribution and elimination of HSA microspheres in vivo....73
• 3.3. Results and discussion...73
• 3.3.1. Properties of HSA microspheres....73
• 3.3.2. Adriamycin incorporation efficiencies....77
• 3.3.3. In vitro drug release and matrix degradation....77
• 3.3.4. Uetrastructural analysis of HSA microsphere disposition....81
• 3.3.5. Distribution and elimination of HSA microspheres in vivo....81
• 3.4. Literature cited...89