Assimopoulou A N, Papageorgiou V P, Kiparissides C
Department of Chemical Engineering, Aristotle University of Thessaloniki, Greece.
J Microencapsul. 2003 Sep-Oct;20(5):581-96. doi: 10.1080/0265204031000148031.
Microcapsules, containing the pharmaceutical substance shikonin, were prepared by the solvent evaporation method in order to enhance shikonin stability (reduce photo-oxidation, polymerization), decrease its hydrophobicity and control its release rate. The effect of various parameters, such as type of polymer, type and concentration of surfactant, solvent volume and mastic gum (Pistacia lentiscus resin) content/concentration as core additive, on the characteristics of the produced microcapsules and the release rate of shikonin, were experimentally investigated. Among the polymers tested for matrix, ethylcellulose (EC) of viscosity 10 cp was the most successful; EC 100 cp and mastic gum result in larger/compact particles with no pores and much slower release. Sodium dodecyl sulphate (SDS) results in microcapsules with desirable morphological and physicochemical characteristics, while polyethylene glycol (PEG) and polyvinyl alcohol (PVA) are not indicated as surfactants in shikonin microencapsulation. Decreasing the solvent volume (dichloromethane) results in increased mean particle size and, thus, in slower release rate of shikonin, while the incorporation of mastic gum in the capsule core results in better control of shikonin release. Finally, the combination of EC 10 cp as matrix, mastic gum as core additive, low dichloromethane (DCM) volume and low SDS concentration results in microcapsules with the best characteristics in terms of efficiency, loading, release and particle size distribution.
为提高紫草素的稳定性（减少光氧化、聚合反应）、降低其疏水性并控制其释放速率，采用溶剂蒸发法制备了含有药物紫草素的微胶囊。实验研究了各种参数，如聚合物类型、表面活性剂类型和浓度、溶剂量以及作为核心添加剂的乳香（乳香黄连木树脂）含量/浓度，对所制备微胶囊的特性和紫草素释放速率的影响。在测试的用于基质的聚合物中，粘度为10厘泊的乙基纤维素（EC）最为成功；EC 100厘泊和乳香会导致形成更大/更致密且无孔隙的颗粒，释放速度更慢。十二烷基硫酸钠（SDS）可得到具有理想形态和物理化学特性的微胶囊，而聚乙二醇（PEG）和聚乙烯醇（PVA）在紫草素微囊化过程中未被表明可作为表面活性剂。减少溶剂量（二氯甲烷）会导致平均粒径增加，从而使紫草素的释放速率变慢，而在胶囊核心中加入乳香可更好地控制紫草素的释放。最后，以10厘泊的EC作为基质、乳香作为核心添加剂、低二氯甲烷（DCM）体积和低SDS浓度相结合，可得到在效率、载药量、释放和粒径分布方面具有最佳特性的微胶囊。
