(78b) Shear and Composition Effects on the Flow and Electrostatic Properties of Pharmaceutical Powders
Most drug products sold on the market today are solid dosage forms, making it largely a powder technology industry. The complex behavior of pharmaceutical powders is not well understood and characterized; specified processing conditions and formulations are determined by extensive trial-and-error procedures, and even the small changes in the said parameters can cause great variations in powder flow and electrostatic properties. There is a growing interest in developing the correlations between the input conditions, processing parameters and the resulting product properties.
In this regard, a parametric study was undertaken to characterize the effects of formulation concentration and processing conditions on the flow and electrostatic properties of pharmaceutically relevant powders. Twelve blends with various concentrations of active ingredient, magnesium stearate as a lubricant and silica as a glidant were subjected to four different shear rates and levels of total strain in a v-blender with an intensifier bar. The resulted formulations were characterized by measuring flow index, dilation volume, yield strength, and impedance. The results showed substantial effects of total strain and, to a lesser extent, the shear rate on the flowability and electrical properties of the studied blends; the optimal levels of shear and additives to achieve the desired flowability were determined.