Flow Characteristics Optimization of Corn Starch and Microcrystalline Cellulose Mixture by Wet Granulation

Wet granulation is a size enlargement operation which is widely used in pharmaceutical field to modify the powder properties. In fact, the friability and hardness of the final solid dosage form (i.e., tablets), may be significantly improved if initial powders are prior granulated to the desired size and shape. In this optic, a parametric study was carried out with two excipients, microcrystalline cellulose and corn starch, two excipients generally used for tabletting but with poor flow characteristics. A laboratory scale mixer granulator Lodige of 4 litres capacity equipped with blades has been used to achieve mixing and wet granulation. The effect of some parameters such as excipients proportions, binder quantity, rotational speed blades, drying temperature, size aperture of screens and residual humidity were investigated. The morphology of obtained granules was visualized by optical microscope (OM) and scanning electron microscope (SEM). Experimental results showed that increasing rotational speed, drying temperature and size screen with reduced value of residual moisture, lead to obtain dense granules of raised size, tightened, with a narrow granulometric distribution and with excellent flow properties. The compacting test gave tablets with satisfactory hardness and friability which are suggested by European Pharmacopoeia.