<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Kosmidis, K</style></author><author><style face="normal" font="default" size="100%">P. Argyrakis</style></author><author><style face="normal" font="default" size="100%">Macheras, P.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">A reappraisal of drug release laws using Monte Carlo simulations: The prevalence of the Weibull function</style></title><secondary-title><style face="normal" font="default" size="100%">PHARMACEUTICAL RESEARCH</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Drug release</style></keyword><keyword><style  face="normal" font="default" size="100%">Monte Carlo simulations</style></keyword><keyword><style  face="normal" font="default" size="100%">Power law</style></keyword><keyword><style  face="normal" font="default" size="100%">Weibull function</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2003</style></year><pub-dates><date><style  face="normal" font="default" size="100%">JUL</style></date></pub-dates></dates><number><style face="normal" font="default" size="100%">7</style></number><publisher><style face="normal" font="default" size="100%">SPRINGER/PLENUM PUBLISHERS</style></publisher><pub-location><style face="normal" font="default" size="100%">233 SPRING ST, NEW YORK, NY 10013 USA</style></pub-location><volume><style face="normal" font="default" size="100%">20</style></volume><pages><style face="normal" font="default" size="100%">988-995</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Purpose. To verify the Higuchi law and study the drug release from cylindrical and spherical matrices by means of Monte Carlo computer simulation. Methods. 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. Results. 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. Conclusions. 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.</style></abstract><work-type><style face="normal" font="default" size="100%">Article</style></work-type></record></records></xml>