Related Experiment Video
Updated: Jun 6, 2026

Methods for Studying the Mechanisms of Action of Antipsychotic Drugs in Caenorhabditis elegans
Published on: February 4, 2014
Release behaviour of clozapine matrix pellets based on percolation theory
Angela Aguilar-de-Leyva1, Tahmer Sharkawi, Bernard Bataille
1Department of Pharmacy and Pharmaceutical Technology, University of Seville, 41012 Seville, Spain. aguilardeleyva@us.es
Abstract:
The release behaviour of clozapine matrix pellets was studied in order to investigate if it is possible to explain it applying the concepts of percolation theory, previously used in the understanding of the release process of inert and hydrophilic matrix tablets. Thirteen batches of pellets with different proportions of clozapine/microcrystalline cellulose (MCC)/hydroxypropylmethyl cellulose (HPMC) and different clozapine particle size fractions were prepared by extrusion-spheronisation and the release profiles were studied. It has been observed that the distance to the excipient (HPMC) percolation threshold is important to control the release rate. Furthermore, the drug percolation threshold has a big influence in these systems. Batches very close to the drug percolation threshold, show a clear effect of the drug particle size in the release rate. However, this effect is much less evident when there is a bigger distance to the drug percolation threshold, so the release behaviour of clozapine matrix pellets is possible to be explained based on the percolation theory.
Related Concept Videos
Modified-Release Drug Delivery Systems: Rate-Programmed II
Oral Drug Delivery Systems: Continuous-Release Systems
Factors Affecting Dissolution: Polymorphism, Amorphism and Pseudopolymorphism
Some polymorphic crystals possess lower aqueous solubility than their amorphous counterparts, leading to incomplete absorption. For instance, the oral suspension of Chloramphenicol, which...
Modified-Release Drug Delivery Systems: Drug Release Characteristics
Factors Influencing Drug Absorption: Pharmaceutical Parameters
Nonlinear Pharmacokinetics: Dependence of Elimination Half-Life and Dose Clearance
A study on guinea pigs examined the...
