Department of Pharmaceutical Technology and Cosmetology, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, Belgrade, Serbia.
Colloids Surf B Biointerfaces. 2011 Mar;83(1):165-72. doi: 10.1016/j.colsurfb.2010.11.024. Epub 2010 Nov 18.
In this study an investigation of a model drug sorption onto cationic surfactant-modified natural zeolites as a drug formulation excipient was performed. Natural zeolite was modified with cetylpyridinium chloride in amounts equivalent to 100, 200 and 300% of its external cation-exchange capacity. The starting material and obtained organozeolites were characterized by Fourier transform infrared spectroscopy, zeta potential measurements and thermal analysis. In vitro sorption of diclofenac sodium as a model drug was studied for all surfactant/zeolite composites by means of sorption isotherm measurements in aqueous solutions (pH 7.4). The modified zeolites with three levels of surfactant coverage within the short activation time were prepared. Zeta potential measurements and thermal analysis showed that when the surfactant loading level was equal to external cation-exchange value, almost monolayer of organic phase were present at the zeolitic surface while higher amounts of surfactant produced less extended bilayers, ordered bilayers or admicelles at the zeolitic surface. Modified zeolites, obtained in this manner, were effective in diclofenac sodium sorption and the organic phase derived from adsorbed cetylpyridinium chloride was the primary sorption phase for the model drug. The Langmuir isotherm was found to describe the equilibrium sorption data well over the entire concentration range. The separate contributions of the adsorption and partition to the total sorption of DS were analyzed mathematically. Results revealed that that adsorption and partitioning of the model drug take place simultaneously.
本研究考察了模型药物在阳离子表面活性剂改性天然沸石上的吸附情况，作为药物制剂赋形剂。天然沸石用氯化十六烷基吡啶改性，用量相当于其外部阳离子交换容量的 100%、200%和 300%。起始材料和获得的有机沸石通过傅里叶变换红外光谱、动电电位测量和热分析进行了表征。通过在水溶液（pH 7.4）中进行吸附等温线测量，研究了所有表面活性剂/沸石复合材料对双氯芬酸钠（一种模型药物）的体外吸附。在短激活时间内用三种表面活性剂覆盖水平制备了改性沸石。动电电位测量和热分析表明，当表面活性剂负载水平等于外部阳离子交换值时，有机相几乎在沸石表面上呈现单层，而较高的表面活性剂用量则在沸石表面上产生较少的扩展双层、有序双层或混合胶束。以这种方式获得的改性沸石对双氯芬酸钠的吸附有效，吸附的十六烷基吡啶氯化物衍生的有机相是模型药物的主要吸附相。发现Langmuir 等温线很好地描述了整个浓度范围内的平衡吸附数据。通过数学分析，对 DS 的吸附和分配对总吸附的单独贡献进行了分析。结果表明，模型药物的吸附和分配同时发生。
