Kosmidis Kosmas, Macheras Panos
Institut für Theoretische Physik III, Justus-Liebig-Universität, Giessen, Germany.
Int J Pharm. 2008 Apr 16;354(1-2):111-6. doi: 10.1016/j.ijpharm.2007.10.036. Epub 2007 Nov 4.
We have studied drug release from matrices with periodic layers of high and low diffusivity using Monte Carlo simulations. Despite the fact, that the differential equations relevant to this process have a form that is quite different from the classical diffusion equation with constant diffusion coefficient, we have found that the Weibull model continues to describe the release process as well as in the case of the "classical" diffusion controlled drug release. We examine the similarities and differences between release from matrices with periodic layers and matrices with random mixtures of high and low diffusivity area and show that the periodic geometrical arrangement of the low diffusivity areas has an influence in the release profile which is negligible for low diffusivity ratios, but becomes important in the case of high diffusivity ratios and for intermediate values of the periodic "length". Such an arrangement in periodic layers leads to Weibull exponent a which are lower than those of the corresponding random arrangement and exponents b which are higher than those of the random case.
我们使用蒙特卡罗模拟研究了具有高扩散率和低扩散率周期性层的基质中的药物释放。尽管与该过程相关的微分方程形式与具有恒定扩散系数的经典扩散方程有很大不同，但我们发现威布尔模型在描述释放过程方面与“经典”扩散控制药物释放的情况一样有效。我们研究了具有周期性层的基质与具有高扩散率和低扩散率区域随机混合物的基质之间的异同，并表明低扩散率区域的周期性几何排列对释放曲线有影响，对于低扩散率比可忽略不计，但在高扩散率比和周期性“长度”的中间值情况下变得重要。周期性层中的这种排列导致威布尔指数a低于相应随机排列的指数，指数b高于随机情况的指数。
