• Archives of Pharmacal Research
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• 제18권1호
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• pp.18-21
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• 1995

Poly(ethylene glycol)(PEG) macrocers teminated with acrylate groups and semi-interpenetrating polymer networks (IPNs) composed of poly-.epsilon.-capolactone(PCL) and PEG macromer were syntheswized with the aim of obtaining a bioerodible hydrogel that could be used to release drugs for implantable delivery system. Polymerization of PEG macromer resulted in the formation of cross-linked gels due to the multifunctionality of macromer. Non-crosslinked PCL chains were interpenetrated into the cross-linked three-dimensions networks of PEG. The IPNs, largw drug loading lower concentration of PEG macromer in the IPNs concentration and the higher molecular weight of PEG macromer. Also, 5-FU was more fast released than hydrocortisone to the increased water solubility.

• Archives of Pharmacal Research
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• 제9권2호
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• pp.63-73
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• 1986

The use of biodegradable polymetric materials as drug carriers is a relatively new dimension in polymeric drug delivery systems. A number of biodegradable or bioerodible polymers, such as poly(lactic/glycolic acid) copolymer, poly($\alpha$-amino acid), polyanhydride, and poly (ortho ester) are currently being investigated for this purpose. These polymers are useful for matrix and reservoir-type delivery devices. In addition, when chemical functional groups are introduced to the biodegradable polymer backdone, such as poly (N-(2-hydroxypropyl) methacrylamide), the therapeutic agent can be covalently bound directly or via spacer to the backbone polymer. These polymer/drug conjugates represent another new dimension in biodegradable polymeric drug delivery systems. In addition, examples of biodegradable polymeric durg delivery systems currently being investigated will be discussed for the purpose of demonstrarting the potential importance of this new field.

• Journal of Pharmaceutical Investigation
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• 제29권1호
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• pp.21-27
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• 1999

Semi-solid poly(ortho esters) (POE) were prepared to provide bioerodible carriers for sustained drug delivery systems of naloxone (NLX) in the treatment of narcotic addiction. As the POE have viscous behavior at room temperature, a significant advantage of this polymer is that it can be injected without any surgical intervention. The POE was synthesized by a transesterification reaction between 1,2,6-hexanetriol and trimethyl orthoacetate, and the structure of the polymer was confirmed by IR. The in vitro release of the drug from POE was studied. The release rate of NLX decreased with increasing intrinsic viscosities of the polymer. In vivo biocompatibility studies were carried out in rats with NLX loaded POE. Histopathological analysis showed that NLX implants are well-tolerated by rats when used subcutaneously. Pharmacokinetic studies of POE-NLX implants of two different viscosities were carried out in rabbits. In all cases, plasma concentrations of NLX were maintained over 1 ng/ml for at least 168 hours, but initial burst effect was observed. Mean residence time(MRT) was found to depend on the viscosity of the polymer.

• Journal of Pharmaceutical Investigation
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• 제29권2호
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• pp.93-98
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• 1999

Semi-solid poly(ortho esters) (POE) were prepared to provide bioerodible carriers for sustained drug delivery systems of nifedipine in the treatment of cardiovascular disease. As the POE has viscous behavior at room temperature, a significant advantage of this polymer is that it can be injected without any surgical intervention. The POE was synthesized by a transesterification reaction between 1,2,6-hexanetriol and trimethyl orthoacetate and the nifedipine release from POE was studied in vitro. The release rate of nifedipine decreased with increasing the amount of nifedipine and the diethanolamine dispersed in the polymer. But the excess amounts, above 3%, of diethanolamine retarded the release of nifedipine. In vivo biocompatibility studies were carried out in rats with nifedipine loaded POE. Histopathological analysis showed that nifedipine loaded POE implants were well-tolerated by rats when used subcutaneously. In case of the rats implanted POE containing diethanolamine, tissue necrosis and inflammation were occured. Pharmacokinetic studies of nifedipine loaded POE implants were carried out in rabbits. In all cases, plasma concentrations of nifedipine were maintained over 15 ng/ml for at least 360 hours and biological half $life(t_{1/2})$ and mean residence time(MRT) were increased by addition of diethanolamine.

• 한국임상수의학회지
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• 제19권2호
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• pp.228-235
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• 2002

유방염은 젖소에 있어서 유량의 감소, 유질 저하로 인한 우유 폐기문제, 젖소의 도태, 치료비 및 노동력의 부담등을 초래하는 가장 경제적 손실이 큰 질환이다. 현재까지 비유기 최종 착유 후에 항생제를 주입하는 건유기 치료법이 유방염 관리에 가장 효과적이며 폭넓게 쓰이고 있는 방법으로 알려져 있다. 하지만, 건유기 치료는 건유기 주입 항생제 제품들이 건유기 초기에만 지속적인 활성을 지니기 때문에 건유기 말기와 분만 전기에 있어서의 신규 감염은 방어할 수 없다. 따라서 본 연구는 건유기 유방염 관리를 위해 PLGA를 이용한 서방형 생분해 cephalexin microsphere를 제조하여 이의 임상적 효능을 평가하고자 하였다. PLGA는 무독성의 조직 반응을 일으키지 않는 특성으로 인해 약물 방출 조절 체계의 일환으로 인정을 받아왔다. 본 연구에서 cephalexin microsphere는 표면에 특징적인 구멍을 가지고 있는 구형 모양으로 확인이 되었으며 약물 방출 시험에서 초기 과다 방출 이후로 21일간 약물의 방출이 점차 감소한 뒤 3주와 4주 사이에 2차 방출을 보이는 맥동성 방출 양상이 관찰되었다. 현장적용 시험에서는 cephalexin microsphere를 주입한 실험군에서 대조군에 비해 분만 후 신규 감염율 및 치료율, 평균 체세포 수의 변화의 측면에서 볼 때 유의성 있는 차이가 있음을 확인하였다. 따라서 생분해 microsphere를 이용한 건유기 치료법은 건유기 동안 신규 감염을 예방하고 기감염을 감소시킴으로써 종전의 건유기 치료를 좀 더 효과적으로 증진시킬 수 있을 것으로 사료된다.