Impact of agitated drying on the powder properties of an active pharmaceutical ingredient

In this study, the impact of agitated drying on the physical and bulk powder properties of an active pharmaceutical ingredient (API) is presented. The effects of different agitated drying conditions such as agitation rate, drying temperature, drying time pre-agitation, drying time during agitation and number of solvent wash cycles on the bulk density, millability, flow and specific surface area is reported. The crystal morphology is altered from fibrous needles to agglomerates when switching from tray to agitated drying. An increase in bulk density and specific surface area was evident when using agitated drying compared to tray drying as hard coarse granules were produced with an increase in the number of fine particles < 10 μm. The bulk density was found to increase with an increase in agitation speed, drying time and number of solvent wash cycles used during filtration. Controlling both fine and coarse particle size of the granules for this API during agitated drying was difficult to achieve due to the fibrous crystal habit. However, the increase in the bulk density observed has the potential to facilitate improvements in the ease of drug product development. In the case of this system further particle size control was required through the use of dry milling.