There are 3 variables that can be manipulated which affect the characteristics of the result produced from spray drying. These variables are process parameters, properties of the liquid feed, and equipment design. The high flow rate of the liquid feed, large nozzle diameter and high formulation concentration are all parameters in which favor the formation of large particles. On the other hand, low surface tension, high atomization pressure and small nozzle diameter are parameters that promote the formation of small particles. In addition, faster solvent evaporation rate which indicates a lower boiling point usually produces more porous particles. This is due to the shorter time it takes for the droplets to shrink.