Kosmidis Kosmas, Argyrakis Panos, Macheras Panos
Department of Physics, University of Thessaloniki, 54124 Thessaloniki, Greece.
Pharm Res. 2003 Jul;20(7):988-95. doi: 10.1023/a:1024497920145.
To verify the Higuchi law and study the drug release from cylindrical and spherical matrices by means of Monte Carlo computer simulation.
A one-dimensional matrix, based on the theoretical assumptions of the derivation of the Higuchi law, was simulated and its time evolution was monitored. Cylindrical and spherical three-dimensional lattices were simulated with sites at the boundary of the lattice having been denoted as leak sites. Particles were allowed to move inside it using the random walk model. Excluded volume interactions between the particles was assumed. We have monitored the system time evolution for different lattice sizes and different initial particle concentrations.
The Higuchi law was verified using the Monte Carlo technique in a one-dimensional lattice. It was found that Fickian drug release from cylindrical matrices can be approximated nicely with the Weibull function. A simple linear relation between the Weibull function parameters and the specific surface of the system was found.
Drug release from a matrix, as a result of a diffusion process assuming excluded volume interactions between the drug molecules, can be described using a Weibull function. This model, although approximate and semiempirical, has the benefit of providing a simple physical connection between the model parameters and the system geometry, which was something missing from other semiempirical models.
通过蒙特卡洛计算机模拟验证 Higuchi 定律，并研究药物从圆柱形和球形基质中的释放情况。
基于 Higuchi 定律推导的理论假设，模拟了一维基质，并监测其随时间的演变。模拟了圆柱形和球形三维晶格，晶格边界处的位点被标记为泄漏位点。使用随机游走模型使粒子在晶格内移动。假设粒子之间存在排除体积相互作用。我们监测了不同晶格尺寸和不同初始粒子浓度下系统的时间演变。
在一维晶格中使用蒙特卡洛技术验证了 Higuchi 定律。发现从圆柱形基质中以 Fick 方式释放的药物可以很好地用 Weibull 函数近似。发现 Weibull 函数参数与系统比表面积之间存在简单的线性关系。
由于假设药物分子之间存在排除体积相互作用的扩散过程，基质中的药物释放可以用 Weibull 函数描述。该模型虽然是近似的和半经验的，但具有在模型参数与系统几何形状之间提供简单物理联系的优点，这是其他半经验模型所缺少的。
