Improving the Functionality of Spray-Dried Powders Using a Template-Assisted Process

Abstract

Spray drying generally leads to amorphous particles, which can lead to manufacturing problems. Hence, there is often a desire to manipulate the process conditions to favor crystallization. In this study, a combined crystallization and spray drying process has been studied using humid air as drying medium. Humid air was used in order to change the drying rate and moisture content of the particles and thus increase the crystallinity of spray-dried lactose. To further improve the functionality of spray-dried particles, a templating approach was used to produce highly-porous lactose particles. Spray-dried and amorphous mixtures of lactose (core material) and different templating agents have been washed with ethanol to remove the template and simultaneously crystallize the lactose. The porous lactose particles that resulted from this treatment had a highly-stable structure of a crystalline powder and also a significant specific surface area. Citric acid as well as carbohydrate sugars were used as templating materials. The resulting particles were characterized as a function of operating conditions, such as the type of templating agents and their concentrations. The high porosity lactose particles produced using the templating approach were then impregnated with drug substances as a new method to formulate and manufacture pharmaceutical materials. A model drug, acetaminophen was used together with poorly-water soluble drugs, such as indomethacin and nifedipine. The introduction of the poorly-soluble drugs into the nanopores of lactose particles led to an increase in the dissolution rates. The templating approach was then used to produce mesoporous CaO sorbent particles for CO2 capture. It was observed that there was a direct link between the pore size distribution of the sorbent and its CO2 capture performance.