INFLUENCE OF 2 DIFFERENT TYPES OF EXCIPIENT ON DRUG PERCOLATION-THRESHOLD

The application of the principles of percolation theory is providing a more rational pharmaceutical dosage form design. The drug percolation threshold is the parameter that provides a better description of the system according to this theory. In order to check the possibility of use the drug percolation threshold as a preformulation parameter, the influence of the main formulation factors is being studied. The aim of this work is to study the influence of the type of excipient on the d rug percolation threshold. For this purpose, two excipients exhibiting Very different mechanical behaviour have been selected. Inert matrice s were prepared using Ethocel(R) 100 and Eudragit(R) RS-PM as excipien ts and KCI as a model drug. Release assays were performed using the ro tating disk method. The drug percolation threshold was estimated emplo ying the method of Leuenberger and Bonny. The following confidence int ervals (95%) were obtained: epsilon(c) = 0.3644 +/- 0.0641 and epsilon (c) = 0.3407 +/- 0.0345 of total porosity for matrices containing Eudr agit(R) RS-PM and Ethocel(R) 100, respectively. On the light of the ob tained results, no significant differences were found on the drug perc olation thresholds for two excipients having very different mechanical behaviour. (C) 1998 Elsevier Science B.V. All rights reserved.