Kikkinides E S, Charalambopoulou G C, Stubos A K, Kanellopoulos N K, Varelas C G, Steiner C A
Institute of Physical Chemistry, NCSR Demokritos, Paraskevi Attikis, Greece.
J Control Release. 1998 Feb 12;51(2-3):313-25. doi: 10.1016/s0168-3659(97)00182-x.
A comprehensive two phase model is developed to describe the sustained release of a solute or drug from a biphasic hydrogel substrate. Such a material consists of a continuous hydrophilic phase (polymer backbone in water) and a dispersion of spherical microdomains made of the hydrophobic side chains of the polymer organised in a micelle like fashion. The solute or drug is assumed to be encapsulated within the dispersed microdomains, and to diffuse from the interior to the surface of the microdomain where it exchanges following a Langmuir isotherm. Mass transfer to the bulk phase occurs by desorption of the drug from the surface through a driving force that is proportional to the difference of surface and bulk concentration. Accordingly the drug is released to the surroundings by diffusion through the bulk. Depending on the values of the Langmuir constant and assuming well stirred behaviour in the interior of the microdomain, the present model results in either of the two asymptotic models developed in previous studies. The results of a parametric study show that the desired steady state flux of a specific drug to the surroundings may be obtained given appropriate values of structural properties of the material. This conclusion is further supported when using this model to simulate earlier experimental results. The polymer structural properties can be manipulated easily during the fabrication of dispersed-phase networks, as indicated by preliminary experiments.
开发了一种综合的两阶段模型来描述溶质或药物从双相水凝胶基质中的持续释放。这种材料由连续的亲水相（水中的聚合物主链）和由聚合物的疏水侧链以胶束状方式组织而成的球形微区分散体组成。假设溶质或药物被包裹在分散的微区内，并从微区内部扩散到微区表面，在那里它按照朗缪尔等温线进行交换。药物通过与表面和主体浓度差成正比的驱动力从表面解吸而发生向主体相的传质。因此，药物通过主体扩散释放到周围环境中。根据朗缪尔常数的值，并假设微区内部行为充分搅拌，本模型导致了先前研究中开发的两种渐近模型中的一种。参数研究结果表明，给定材料结构特性的适当值，可以获得特定药物向周围环境的所需稳态通量。当使用该模型模拟早期实验结果时，这一结论得到了进一步支持。如初步实验所示，在分散相网络的制造过程中，可以轻松地控制聚合物的结构特性。
