Determination of the Critical Stress Intensity Factor (KIC) for MicrocrystallineCellulose (MCC) using a developed tensile stress method and its application todouble-layer tablets

摘要

Tablets that have layered compaction zones, produced by different compactionpressures have been found to enable a controlled release rate profile of active ingredients:a desirable characteristic of powder compacts that can be difficult to achieve with singlycompacted tablets. An observed disadvantage of some multi-layered tablets is theinterfacial weakness between the individual layers, which can cause the tablet to fracture bycapping.Single and double layered tablets of the excipient Microcrystalline Cellulose (MCC),FMC Corp., have been studied using an axial tensile stress method, originally developed todetermine the tendency of a single compacted tablet to fracture by capping [1]. Themethodology was assessed by finding the critical stress intensity value at zero porosity(KIC0), using conventional fracture mechanics principles, for singular compacted MCC. Theresult of 0.86 Mpa.m0.5 has been found to be in good agreement with other published work[2-7].The interface tensile strength of double layered compacts has been found toincrease with a rise in applied stress on the upper layer (when initial compaction stress isheld constant). Initial investigations to explain the discrepancies of interface strength ofcompacts subjected to different applied stresses have begun.