Kazlauske Jurgita, Gårdebjer Sofie, Almer Sara, Larsson Anette
Pharmaceutical Technology, Applied Chemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden; SuMo Biomaterials, VINN Excellence Center, Chalmers University of Technology, 412 96 Gothenburg, Sweden.
SuMo Biomaterials, VINN Excellence Center, Chalmers University of Technology, 412 96 Gothenburg, Sweden; Theoretical Chemistry, Lund University, P.O. Box 124, 221 00 Lund, Sweden.
Int J Pharm. 2017 Mar 15;519(1-2):157-164. doi: 10.1016/j.ijpharm.2016.12.021. Epub 2016 Dec 12.
Previous investigations of aqueous based ethyl cellulose (EC) latex dispersions have mainly focused on the commercially available viscosity grade 20cps. In this study, dispersions of EC with varying viscosity grades (which correspond to molecular weights), ranging from 4 to 100 cps, were produced and characterised. The dispersions showed particle sizes around 200nm and highly negative ζ-potentials (approx. -100mV), which indicated stable dispersions as confirmed by sedimentation studies. The different latexes were used to produce free-standing film coatings. We hypothesised that the different viscosity grades of EC would result in different properties of the films. We found that an increase in viscosity grade (and higher molecular weight) resulted in lower coalescence between the particles during film formation and thus to higher water permeability than in film coatings of lower molecular weight. After exposure to water the EC 4cps and 20cps film coatings had a more porous structure in the side facing the air during production and drying after immersion in water. Molecular weight is therefore a factor that should be considered when producing pharmaceutical coatings for controlled release.
以往对水性乙基纤维素（EC）胶乳分散体的研究主要集中在市售粘度等级为20cps的产品上。在本研究中，制备并表征了粘度等级（对应分子量）从4到100cps不等的EC分散体。这些分散体的粒径约为200nm，ζ电位高度为负（约-100mV），沉降研究证实这表明分散体是稳定的。使用不同的胶乳制备自支撑薄膜包衣。我们假设不同粘度等级的EC会导致薄膜具有不同的性能。我们发现粘度等级增加（以及分子量更高）会导致成膜过程中颗粒之间的聚结减少，因此与较低分子量的薄膜包衣相比，具有更高的透水性。在接触水后，4cps和20cps的EC薄膜包衣在生产过程中面向空气的一侧以及浸入水中干燥后具有更多孔的结构。因此，在生产控释药物包衣时，分子量是一个应考虑的因素。
