Critical Points in Multiparticular Matrix Systems

The percolation theory has been widely applied to the study of monolithic matrix systems. However, it was not applied to the study of multiparticular matrix system until the study 

The results of this study show that the distance to the HPMC percolation threshold has an effect on the drug release rate, and as explained in previous sections, this behavior is typical of hydrophilic matrices. Nevertheless, in the studied multiparticulate matrix systems, the drug percolation threshold also exerts an important influence on the release behavior. This is a typical behavior of inert matrices. Therefore, an intermediate behavior between inert and hydrophilic matrices was found for the studied MCC/HPMC multiparticulate matrices. 

On the other hand, a clear effect of the drug particle size in the release rate has been appreciated in lots formulated in the vicinity of the drug percolation threshold, being this effect less evident when the distance to the drug percolation threshold increases. This provides a rational explanation to the gosh effect of the particle size, previously mentioned by several authors. 

Although more research is needed in this field, the percolation theory is providing a science-based explanation of the behavior of matrix systems including inert and hydrophilic matrices in the form of monolithic or multiparticulate systems. 

4 Critical Points in Matrix Tablets Prepared by Ultrasound-Assisted Compression 

---