(392b) Experimental and Numerical Analysis of Attrition in Pharmaceutical Sieve Cuts

Attrition of granules during the pharmaceutical tabletting process can adversely affect process performance and product quality. The type and degree of attrition is highly dependent upon the type of granulation used in the formulation. This study characterized the attrition that occurs within various size classes for two different granulation processes: fluidized bed granulation (FBG) and high shear granulation (HSG). Granules from each type of process were sieved and particle size distribution (PSD) information obtained via a standard bench-top laser diffraction unit. It was found that HSG granules are stronger than FBG granules across all sieve cuts examined. The general attrition mechanism for HSG was determined to be ?chipping" whereas fragmentation defined FBG attrition. Population balance equations incorporating a power-law breakage kernel and the empirical Austin daughter distribution function were then used in an attempt to further evaluate the granule types and sizes. The high calculated breakage rate for FBG granules, relative to the HSG granule breakage rate, qualitatively matched the experimental observations. In addition, the final PSDs as calculated by the model matched well with the experimental distributions in all sieve cuts. However, each sieve cut had a unique set of user-defined parameters as inputs into the model. Preliminary attempts to define the final PSD of each individual sieve cut via a single set of model parameters have been unsuccessful. Research continues along this front. In parallel, limitations associated with the model choice continue to be investigated.