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首页> 外文期刊>Journal of Microencapsulation: Microcapsules Liposomes Nanoparticles Microcells Microspheres >Evaluation of enteric matrix microspheres prepared by emulsion-solvent evaporation using scanning electron microscopy
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Evaluation of enteric matrix microspheres prepared by emulsion-solvent evaporation using scanning electron microscopy

机译：使用扫描电子显微镜评估乳液-溶剂蒸发制得的肠溶基质微球

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Theophylline microspheres were prepared by the emulsion-solvent evaporation method using cellulose acetate butyrate (CAB381-20) and mixtures of CAB381-20~R and cellulose acetate phthalate.The physical state of the drug,polymers and microspheres surfaces were determined using scanning electron microscopy.For those microspheres prepared using mixtures of CAB381-20 and cellulose acetate phthalate,scanning electron micrographs were taken before dissolution and also at different stages of dissolution (in SGF,pH 1.2 and in simulated intestinal fluid,pH 7.5).Micrographs were taken of the outside surfaces of the microspheres and of the cleaved microspheres showing their interiors (core).Drug crystals were observed on or near the surface of microspheres prepared from the polymer mixtures,while no drug particles or crystals were seen on the surfaces of microspheres prepared solely from CAB381-20.An acid wash for less than 2min was capable of extracting all drug on the surface of the microspheres prepared from a mixture of CAB381-20 and cellulose acetate phthalate.The absence of drug crystals on the surface of CAB381-20 microspheres is believed to prevent initial drug release and create a lag time in release profiles.Results suggest that in both microsphere formulations,a layer of drug-free polymer is formed outside the core matrix and is believed to be responsible for the near zero-order release profiles.
机译：茶碱微球采用乙酸丁酸纤维素（CAB381-20），CAB381-20〜R和邻苯二甲酸乙酸纤维素的混合物通过乳液-溶剂蒸发法制备。用扫描电子显微镜测定药物，聚合物和微球表面的物理状态。对于使用CAB381-20和邻苯二甲酸醋酸纤维素混合物制备的微球，在溶解前以及在溶解的不同阶段（在SGF中，pH 1.2和在模拟肠液中，pH 7.5）中均拍摄了扫描电子显微照片。在由聚合物混合物制得的微球表面上或附近观察到药物晶体，而在仅制备的微球表面上未观察到药物颗粒或晶体。来自CAB381-20的酸洗时间不到2分钟，能够在微球表面上提取所有药物由CAB381-20和邻苯二甲酸醋酸纤维素的混合物制备而成。据信CAB381-20微球表面不存在药物晶体，可以防止药物的初始释放并在释放曲线中产生滞后时间。结果表明，在两种微球制剂中，在核心基质外部形成一层不含药物的聚合物，据信这是近零级释放曲线的原因。

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