Percolation theory and the role of maize starch as a disintegrant for a low water-soluble drug.

The objective of the present work is to investigate the presence or absence of a critical concentration of maize starch according to the percolation theory for a truly ternary system with respect to a minimum disintegration time. The results of this study show that the application of percolation theory is not limited to the study of binary systems. In this work it is shown how it can be used to analyze the behavior of binary and ternary systems for caffeine and mefenamic acid formulations containing a starch-based disintegrant. The percolation threshold p(c) can be described by the volumetric ratio of the disintegrant to the drug substance being equal to p(c) = 0.2 (v/v) in in which both components have similar average particle sizes. In addition, the behavior of the disintegration time in the neighborhood of the percolation threshold can be mathematically modeled with the basic equation of the percolation theory yielding a critical exponent q = 0.28 +/- 0.06.