Fractal and reactive dimension in inert matrix systems

The aim of this work is to use the fractal geometry to explain the behaviour of inert matrix systems during the release process. First, the Menger sponge with a fractal dimension of 2.727 was chosen as a model of pore-system to characterize the porous body generated by leaching tablets containing a water-insoluble polymer (Eudragit(R) RS 100) and a model water-soluble drug (C1Na). The fractal dimension, D, of inert matrix systems is calculated by mercury porosimetry. A direct relation between the value of D and the particle size of binary systems has been established. Second, the reactive dimension parameter is considered to determine the effective surface during the release test. The comparison between D and D-R has allowed to illustrate that the release process is governed by two phenomena: roughening and trapping.