Screening of high shear mixer melt granulation process variables using an asymmetrical factorial design

The effects of process conditions on the granulometric characteristics of a placebo formulation prepared in a 10 l high shear miser by single-step mel t granulation were studied. The factors under investigation were: binder gr ade, mixer load, presence of the deflector tall of analysed at two levels), binder concentration, impeller speed, massing time, type of impeller blade s (these four at three levels) and jacket temperature (considered at four l evels). Two granule characteristics were analysed: the geometric mean diame ter and the percentage of particles finer than 315 mu m. In order to screen simultaneously the above-mentioned factor levels: an asymmetrical Factoria l design was adopted, which allowed the reduction in the number of runs fro m 2592 to 25, Additionally, this technique permitted the selection of the f actor levels which have the major 'weight' on the two granule characteristi cs under study. Two additional trials were performed to attest the screenin g validity. (C) 1999 Elsevier Science B.V. All rights reserved.