The influence of five selected processing and formulation variables on the particle size, particle size distribution, and friability of pellets produced in a rotary processor

A factorial-designed study has been performed to investigate the effect of two formulation variables and three processing variables on size, size distribution, and friability of pellets made in a rotary processor by the wet granulation technique. The first are the microcrystalline cellulose content and the ratio of the amount of added water to the amount of microcrystalline cellulose in the powder mixture; the latter are the rotor speed, the spheronization time after water addition, and the water addition rate. Bath formulation variables and the three processing variables have a major influence an pellet size and percentage loss in weight in the friability test. With the exception of the spheronization time, increasing an independent variable results in a wider size distribution. The wet granulation technique in the rotary processor has been judged to be a critical technique. However, if all variables are fully controlled, rather good reproducibility can be obtained.